Natural fibers in sustainable materials: extraction technologies, fiber modification, and performance–sustainability relationships

Abstract

Natural fibers have emerged as sustainable alternatives to synthetic materials in textile applications due to their biodegradability, renewability, and diverse functional properties. Derived from plant, animal, and mineral sources, fibers such as cotton, jute, hemp, flax, silk, and bamboo demonstrate excellent physical and mechanical characteristics suitable for apparel, home furnishing, and industrial textiles. Their utilization supports circular production systems, reduces dependency on petroleum-based resources, and minimizes environmental impacts such as pollution and greenhouse gas emissions. The review comprehensively analyzes the properties, extraction methods, and modifications of natural fibers, highlighting advanced processing techniques like enzymatic and microwave-assisted retting that enhance quality while lowering ecological footprints. Furthermore, it discusses the socio-economic benefits of natural fiber industries, including rural employment generation and resource-efficient production from agricultural residues. Despite challenges related to variability, water use, and processing costs, ongoing research in fiber surface treatment and composite technology is driving innovation and improving performance. The integration of natural fibers into textile manufacturing represents a crucial pathway toward achieving sustainable fashion, environmental stewardship, and a circular bio-economy.

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1 Introduction

Material selection plays a critical role in sustainable engineering design, as the physical and mechanical properties of materials determine product performance, cost, manufacturability, and environmental impact. Among eco-friendly fibers, natural fibers have gained wide attention due to their ease of processing, high productivity, and potential for cost reduction.^1,2 Their properties can be optimized by varying the type and proportion of reinforcement and matrix phases.³ In this context, natural fibers have emerged as promising reinforcements in polymer composites because they are renewable, biodegradable, low-cost, and widely available.^4,5 The density of natural fibers (1.2–1.6 g cm⁻³) is significantly lower than that of glass fiber (2.4 g cm⁻³), which enables the fabrication of lightweight composites with good specific mechanical properties. Consequently, natural fibers such as hemp, jute, sisal, banana, coir, and kenaf have found applications in various sectors, including automotive interiors, furniture, construction, packaging, and shipping pallets.⁶ Their utilization also aligns with the growing demand for environmentally friendly and sustainable materials in textile and composite manufacturing.

Natural fibers are obtained from different biological sources, including plants and animals, such as wool, chicken feathers, hair, and silk.⁷ Plant-based fibers consist mainly of cellulose, hemicellulose, pectin, lignin, waxes, and other extractives that define their structural, chemical, and mechanical characteristics. However, their hydrophilic nature often limits compatibility with hydrophobic polymer matrices, leading to poor interfacial adhesion and moisture sensitivity. Chemical treatments such as alkali, silane, or acetylation are commonly used to reduce hydroxyl groups, increase surface roughness, and improve fiber–matrix bonding.^8,9 Meanwhile, the rising global emphasis on sustainability, depletion of petroleum-based resources, and stricter environmental regulations have accelerated interest in bio-based materials.¹⁰ Agricultural residues such as cereal straw, corn stalks, cotton residues, bagasse, and grasses offer abundant and low-cost lignocellulosic biomass. The effective utilization of these residues can minimize open-field burning, reduce pollution, and promote rural industrialization and circular economy models.¹¹ These bioresources thus play a dual role by addressing waste management issues and providing a renewable feedstock for textile industries.

The physical and chemical characteristics of natural fibers, such as cell-wall thickness, fiber dimensions, cross-sectional geometry, and lumen structure, along with the relative composition of cellulose, hemicellulose, and lignin, significantly influence their tensile strength, stiffness, thermal stability, moisture absorption, and biodegradation behavior.¹² Moreover, the availability and characteristics of these fibers vary across geographical regions due to differences in climate, soil conditions, and agricultural practices. Understanding the global distribution of bioresources is therefore essential to identify region-specific fibers for sustainable industrial applications. In this context, the next section of this paper focuses on the bioresources and geographical distribution of natural fibers across different countries, providing an overview supported by a global map representation. The objective of this review is to systematically compile and compare plant-, animal-, and mineral-based natural fibers with respect to their origin, classification, key physical, chemical, and thermal properties, and modification routes relevant to textile and composite processing. Particular attention is given to linking fiber structure and surface treatments with energy demand during processing and the resulting environmental and sustainability implications. By organizing dispersed data from existing studies into a unified framework that connects material properties, application-based classification, and sustainability assessment, this review provides a clear reference for selecting natural fibers for textile and composite applications based on functional and environmental criteria.

2 Global distribution of natural fibers

Natural fibers are abundantly available worldwide and are derived primarily from plant, animal, and mineral sources. Fig. 1 illustrates the global distribution of natural fiber availability by country, while Table 1 presents production statistics of major natural fibers. Plant-based fibers dominate global production due to their wide availability, renewability, and adaptability to tropical and subtropical climates.

Fig. 1 Global distribution of natural fiber sources and their major production regions.

Table 1 Worldwide production of natural fibers with corresponding producing countries

Country name	Production (tons)	Source	Ref.
Bangladesh, China, India	2 300 000	Jute	13–15
Bangladesh, China, India, Indonesia, Malaysia	160 000 000	Rice husk	16 and 17
Bangladesh, China, India, Indonesia, Malaysia	579 000	Rice straw	15 and 18
Bangladesh, India, United States	970 000	Kenaf	13–15 and 19
Belgium, Canada, France	830 000	Flax	13–15 and 19
Brazil, China, India	75 000 000	Sugarcane bagasse	13–15 and 19
Brazil, Kenya, Tanzania	378 000	Sisal	13–15 and 19–22
Brazil, China, India, Philippines	100 000	Ramie	13–15 and 19–22
Canada, China, United States	1 750 000 000	Wood fiber	14 and 18
China, France, Philippines	214 000	Hemp	23 and 24
China, India, Indonesia, Malaysia, Philippines	30 000 000	Bamboo	13–15 and 19
Costa Rica, Ecuador, Philippines	70 000	Abaca	13–15, 19 and 22
India, Malaysia, Philippines, Sri Lanka	100 000	Coir	25
Indonesia, Malaysia	40 000	Oil palm	26
Indonesia, Philippines, Thailand	74 000	Pineapple leaf	13–15 and 19–22
Australia, China, New Zealand, United Kingdom, Argentina	1 100 000	Wool	27 and 28
China, India	91 221	Silk	29 and 30
China, Mongolia	25 000	Cashmere	31
South Africa	5000	Mohair	31
Peru, Bolivia, Chile	7000	Alpaca	31
Peru	<10	Vicuña	31
Russia, China, Brazil, Kazakhstan	2 000 000	Asbestos	32

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Musa plants (Musa acuminata), belonging to the Musaceae family, are native to Southeast Asia and generate high-fiber biomass from bunches, pseudostems, leaves, and stalks.³³ Banana fiber is widely available in tropical regions such as Malaysia and South India and is the fourth most important crop in developing countries.³⁴ Abaca (Musa textilis) is mainly cultivated in Talaud, North Sulawesi, where five superior local varieties were released in 2019.³⁵ Pineapple leaf fiber (Ananas comosus L. Merr.) is an underutilized agricultural waste material abundant in Southeast Asia, India, and South America.³⁶ Indonesia contributes approximately 23% of global pineapple production, supported by favorable tropical climatic conditions.

Bamboo is a lignocellulosic fiber from the Graminae family with broad application potential. Bamboo fibers are aligned longitudinally and exhibit good mechanical performance.³⁷ After China and India, Indonesia ranks third in bamboo production and hosts around 160 bamboo species, including 88 endemic species. Betung bamboo (Dendrocalamus asper) is among the most commonly utilized species.³⁸ Cotton fiber (Gossypium sp.), a fruit fiber widely used in textiles and healthcare products, is mainly produced in the USA, Egypt, India, and Brazil. Cotton fibers are classified into long, medium, and short categories based on fiber length.³⁹ Despite increasing demand, cotton production remains limited in some regions due to low productivity and reduced farmer interest.

Ramie (Boehmeria nivea) is a fast-growing bast fiber known for its compatibility with other fibers and high productivity. Global ramie production is approximately 100 thousand tons per year, exceeding abaca production at around 70 thousand tons per year.^40–42 Sisal (Agave sisalana) is a drought-resistant leaf fiber plant that can be cultivated on marginal land and contributes nearly half of global hard fiber textile production.⁴³ Indonesia produces about 500 tons of sisal fiber annually, extracted from plant leaves.⁴² Kenaf (Hibiscus cannabinus L.) is adaptable to diverse soil conditions, with productivity ranging from 2.0 to 4.0 tons of dry fiber per hectare, and is mainly produced in India and Pakistan.⁴⁴ Corn plants, widely cultivated across Asia, also offer high potential as natural fiber sources from stems, leaves, and husks.

Animal-based natural fibers contribute smaller volumes but higher economic value compared to plant fibers. Wool is the most significant animal fiber and plays an important role in the economies of producing countries.²⁷ Major wool-producing regions include Australia, China, New Zealand, the United Kingdom, and Argentina, with Australia contributing approximately 25% of global greasy wool exports by value.²⁷ Wool prices generally range from USD 3 to 12 per kilogram, depending on micron count and origin.²⁸ Silk production, although limited in volume, holds high economic value. Global raw silk production reached 91 221 metric tons between 2011 and 2022, with China and India dominating production and China maintaining a historically strong position in processing.^29,30 Raw silk typically commands prices between USD 30 and 60 per kilogram.²⁹

Luxury animal fibers such as cashmere, mohair, alpaca, vicuña, camel hair, and angora are characterized by low production volumes and exceptionally high market value.⁴⁵ China and Mongolia dominate global cashmere production, with China supplying 60–70% of total output.³¹ South Africa contributes approximately 50% of global mohair production, while alpaca fiber production is concentrated in Peru, accounting for over 75% of global supply.³¹ Although vicuña fiber is produced in negligible quantities, it is among the most valuable natural fibers, with prices estimated at USD 1500–3000 per kilogram.³¹ Economically, East Asia leads global animal fiber production value, followed by Western Europe and Oceania for fine wool, and Andean countries for specialty fibers.^28,31 Increasing consumer preference for high-quality and sustainable textiles has further strengthened demand for animal fibers.²⁸ Keratin-based animal fibers are also being explored for sustainable composite applications due to their flame-retardant behavior and reinforcement potential.⁴⁶

Mineral-based fibers have historically contributed to natural fiber use, with asbestos being the most prominent due to its high tensile strength, chemical resistance, and thermal stability.⁴⁷ However, asbestos is classified as a human carcinogen and is banned or strictly regulated in more than 70 countries.⁴⁸ Despite these restrictions, global asbestos production remained approximately 2 million tons per year as of 2016, with about 90% originating from Russia, China, Brazil, and Kazakhstan.³² Although global consumption has declined, asbestos use increased in several developing regions as of 2013, particularly in the Asia-Pacific, which consumed over half of global asbestos production in 2011.^49,50 Due to the long latency period of asbestos-related diseases, ranging from 20 to 50 years, health impacts persist even after complete bans, with an estimated 125 million people occupationally exposed worldwide and approximately 255 000 deaths annually attributed to asbestos-related causes.⁵¹

The decline of asbestos has increased interest in alternative mineral fibers for composite applications. While mineral fibers differ from biologically derived natural fibers, they are often discussed alongside them in engineering contexts.⁵² Basalt fiber, derived from volcanic rock, exhibits favorable mechanical performance, thermal stability, chemical durability, moisture resistance, and recyclability. Production is concentrated in Russia, China, India, and Germany, although global output remains limited and detailed production statistics are not publicly consolidated.⁵³

3 Properties of natural fibers

3.1 Physical and mechanical properties

Natural fibers exhibit a wide range of physical and mechanical properties depending on their botanical source, microstructure, and chemical composition. In addition to plant-based fibers, animal- and mineral-based natural fibers exhibit distinct physical and mechanical behaviors due to their protein-based and inorganic compositions, respectively. Table 2 shows the physical and mechanical properties of various natural fibers collected from different literature sources. The density of these fibers typically ranges between 0.55 and 1.60 g cm⁻³, which is significantly lower than that of synthetic fibers, making them attractive for lightweight composite applications. Animal fibers such as wool and silk also exhibit relatively low densities and favorable strength-to-weight ratios, whereas mineral fibers generally show higher density and lower elongation characteristics.⁵⁴

Table 2 Physical and mechanical properties of different natural fibers

Natural fiber	Density (g cm^−3)	Diameter (µm)	Tensile strength (MPa)	Young's modulus (GPa)	Elongation at break (%)	Ref.
Abaca	0.83	1.5	900	12–13.8	3–12	55
Agave	1.20	126–344	—	—	7.07	56
Bamboo	0.51–0.72	21–26	225	17.2	3	57
Banana	1.35	50–250	600	17.85	3.36	56
Coir	1.15	100–450	131–175	4–6	4–6	58 and 59
Cotton	1.51–1.6	2–7	287–597	5.5–12.6	3–10	58 and 60
Date	0.99	—	309	11.32	2.73	56
Flax agatha	1.50–1.53	14.4–15.6	962–1800	46–96	—	61
Henequen	1.4	—	430–580	—	—	14
Hemp	1.48	26.5	514	24.8	1.5–4	61–63
Hardwood	0.3–1.2	—	—	5.2–37.9	—	64 and 65
Jute	1.3–1.45	25–200	393–773	13–26.5	1.5–1.8	20 and 58
Kenaf	1.3	—	233	40–53	1.8	66–68
Kudzu	—	—	130–418	—	—	64
Luffa	0.82	25–60	385	12.2	—	66
Napier	0.36	—	73	5.68	1.4	69
Nettle	0.72	15.5–24.3	1594	59–115	—	70 and 71
Okra	—	61–93	184–557.3	8.9–11.8	4–8	56
Oil palm	0.7–1.55	—	—	1–9	8–25	64
Palmyrah	1.09	8	180–215	4.4–6.1	—	72
Pineapple leaf	1.07–1.50	20–80	413–1627	34.5–82.5	1.6	66
Ramie	1.51	34	400–968	60–128	3.6–3.8	58 and 61
Rice husk	2.30–2.36	45	—	—	—	73
Saw dust	0.31–0.32	75–600	16–24	(0.2–0.36) × 10^−3	—	74 and 75
Sea grass	1.50	5	453–692	3.1–3.7	13–26.3	56
Sisal	1.45	50–200	468–640	9.4–22	3–6	20 and 58
Softwood	1.5	—	1000	0.04	4.4	55
Sugar palm	1.29	50–800	190.29	3.69	—	72
Sugarcane bagasse	0.33	67–312	222	27.1	—	66
Wood chips	0.28–0.32	3000–16000	—	(0.25–0.33) × 10^−3	—	75
Alpaca wool	—	18–35	—	—	25–35	76
Sheep wool	—	22–55	100–200	—	25–35	76
Goat wool	—	10–35	—	—	25–35	76
Bombyx mori silk	—	10–24	350–500	5–12	10–24	77
Tussah silk	—	50–70	400–600	9–15	10–25	77
Asbestos	—	—	200–1000	—	<3	78

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Abaca fiber generally possesses a density of about 1.50 g cm⁻³, showing elongation between 3 and 12%, tensile strength reaching up to 980 MPa, and a modulus of elasticity around 12–72 GPa, indicating high stiffness and strength as reported by Biagiotti et al.⁷⁹ Bagasse fiber, on the other hand, shows much lower density, ranging from 0.55 to 1.25 g cm⁻³, with tensile strength values varying from 20 to 350 MPa and modulus between 0.5 and 27 GPa. The relatively lower strength of bagasse compared to abaca is attributed to its higher lignin content and porous cell structure as indicated by Yan et al.⁸⁰

Bamboo fiber demonstrates an intermediate behavior, with density values between 0.60 and 1.50 g cm⁻³, elongation varying from 1.3 to 7%, tensile strength in the range of 140–800 MPa, and modulus between 11 and 36 GPa. These values suggest that bamboo fiber offers a favorable balance between flexibility and strength, a property emphasized in the works of Sathishkumar et al.⁵⁶ and Sujaritjun et al.⁸¹ Similarly, banana fiber exhibits densities between 0.75 and 1.35 g cm⁻³, elongation at break ranging from 1–9%, tensile strength from 54–914 MPa, and modulus between 7.7 and 32 GPa. The moderate stiffness and strength of banana fiber are linked to its semicrystalline cellulose regions and the presence of natural microvoids.⁸²

Coconut fiber, being highly lignified, exhibits a comparatively low density ranging from 0.38 to 1.10 g cm⁻³, tensile strength between 83 and 222 MPa, and modulus values close to 12–32 GPa. Despite the low tensile properties, its high elongation makes it suitable for energy-absorbing and cushioning applications, as highlighted by Danso et al.⁸³ Coir fiber, another lignocellulosic fiber from the same family, possesses densities around 1.15–1.25 g cm⁻³, an extremely high elongation of 15–51%, tensile strength from 95 to 304 MPa, and modulus values up to 6 GPa. The high extensibility and ductile nature of coir fiber are consequences of its elevated lignin content.^84,85

Cotton fiber is comparatively dense, around 1.50–1.60 g cm⁻³, with elongation between 3 and 10%, tensile strength ranging from 200 to 800 MPa, and modulus values within 5.5–13 GPa. Its moderate stiffness and consistent strength have been widely reported in studies by Wambua et al.⁸⁶ and Saba et al.⁸⁷ Flax fiber, one of the strongest bast fibers, shows a density near 1.50 g cm⁻³, tensile strength from 345 to 2000 MPa, elongation between 1 and 4%, and modulus as high as 103 GPa. The superior strength and stiffness of flax are associated with its high cellulose content and low microfibrillar angle.^88,89

Zhang et al.⁹⁰ and Pickering et al.⁹¹ demonstrated that hemp fiber shows similar performance, with density between 1.40 and 1.50 g cm⁻³, tensile strength in the range of 270–1110 MPa, elongation from 1 to 4%, and modulus values up to 90 GPa. The high mechanical properties of hemp are the result of its high cellulose crystallinity and strong fibrillar alignment. Jute fiber, another commonly used bast fiber, exhibits density values from 1.30 to 1.50 g cm⁻³, elongation between 1.5 and 3%, tensile strength of 200–800 MPa, and modulus between 10 and 55 GPa. The variability in jute's tensile strength is due to its nonuniform fibrillar structure and variations in retting quality.^92,93

Pineapple leaf fiber possesses excellent mechanical characteristics with density between 1.07 and 1.56 g cm⁻³, elongation of up to 14.5%, tensile strength reaching 1627 MPa, and modulus between 60 and 82 GPa. These outstanding values are mainly due to its high cellulose content and strong inter-fibrillar bonding, as observed by Abiola et al.⁸² and Saba et al.⁸⁷ Ramie fiber also shows exceptional stiffness, with density around 1.50 g cm⁻³, elongation between 1.2 and 4%, tensile strength from 400 to 938 MPa, and modulus as high as 128 GPa. The strong crystalline regions and highly oriented microfibrils of ramie account for its excellent load-bearing capacity.^19,85

Sisal fiber demonstrates a moderate to high level of mechanical strength, with density between 1.30 and 1.50 g cm⁻³, elongation from 2 to 7%, tensile strength varying between 350 and 855 MPa, and modulus between 9 and 38 GPa. The good balance of stiffness and ductility in sisal is largely due to its moderate cellulose and lignin contents.^93–95

Animal fibers such as wool and silk are primarily protein-based materials. Wool fibers consist mainly of keratin with a helical molecular structure and disulfide bonds, which contribute to their elasticity and resilience.⁷⁶ This structure results in moderate tensile strength, typically around 100–200 MPa, and high elongation at break in the range of 25–35%, as well as good thermal insulation and moisture absorption properties.⁹⁶ Wool fibers have also been investigated as reinforcements in polymer composites, showing improved mechanical performance.^9,10 Silk fibers, composed mainly of fibroin with highly ordered β-sheet structures, exhibit higher tensile strength and stiffness compared to wool, and their mechanical properties can be further enhanced through processing and modification, reaching strengths comparable to spider silk.⁷⁷

In contrast, mineral fibers mainly refer to asbestos, which consists of naturally occurring fibrous silicate minerals. Asbestos fibers exhibit high tensile strength, typically ranging from 200 to 1000 MPa, combined with very low elongation at break, usually below 3%, as well as excellent thermal, chemical, and electrical resistance. Although these properties historically made asbestos valuable in industrial applications, its use has been largely discontinued due to its carcinogenic nature and associated health risks.⁷⁸

In general, fibers such as flax, hemp, ramie, pineapple, and sisal exhibit the highest tensile strength and modulus values, confirming their suitability for high-performance structural composites. In contrast, fibers like coir, bagasse, and coconut, while possessing lower tensile strengths, display higher elongations and energy absorption capabilities, making them better suited for flexible or impact-resistant materials. Animal fibers are particularly suitable for insulation, damping, and bio-composite applications due to their renewability and biodegradability, whereas mineral fibers are characterized by extreme durability but limited applicability because of environmental and health concerns.

3.2 Biological properties

One of the most significant biological properties of natural fibers is their biodegradability.⁹⁷ Unlike many synthetic plastics that persist in the environment for centuries, natural fibers can be decomposed by microorganisms (e.g., bacteria, fungi) into simpler compounds, such as carbon dioxide, methane, water, and biomass.⁹⁸ This characteristic makes them a sustainable alternative, reducing waste accumulation and environmental pollution. The rate and extent of biodegradation are influenced by the fiber's physicochemical structure, including its chemical composition and crystallinity, as well as environmental conditions like temperature, moisture, and microbial activity, as shown in Table 3.⁹⁹ Cellulose, a primary component of plant-based natural fibers, is generally biodegradable. The degradation process is often assessed through weight loss, strength reduction, and morphological changes over time. For instance, wool, a natural keratin fiber, and cotton, a natural cellulose fiber, exhibit significant biodegradability in natural soil and aqueous media at 35 °C over 42 days.¹⁰⁰ Similarly, researchers have investigated the degradation of cellulose fibers functionalized with nanoparticles in soil burial tests and model compost, demonstrating their potential for sustainable disposal after use.¹⁰¹ The presence of lignin, another major component in lignocellulosic fibers, can impact biodegradability by providing rigidity and resistance to microbial degradation.¹⁰² However, biochar derived from lignocellulosic biomass, such as walnut shells, can enhance microbial communities' abundance and degradation of lignocellulosic materials in anaerobic digestion.¹⁰³ Cellulose, with its linear chain of glucose monomers, provides strength, while the more branched hemicellulose and complex phenolic lignin contribute to the fiber's overall structure and resistance.¹⁰²

Table 3 Comparative biological characteristics of natural plant-based and animal-based fibers

Property	Plant-based natural fibers	Animal-based natural fibers
Biodegradation behavior	Rapidly biodegradable in soil and aquatic environments via microbial activity.^104,105 Degradation rate is governed by polysaccharide accessibility and inversely correlated with lignin content^106	Biodegradable under natural and composting conditions through microbial enzymatic activity targeting protein backbones^104,105
Biodegradation mechanism	Enzymatic hydrolysis by cellulases and hemicellulases, leading to progressive mass and mechanical property loss^107,108	Proteolytic degradation of keratin and fibroin chains by microorganisms^104,105
Representative evidence	Hemp, jute, sisal, ramie, regenerated cellulose, and Tipuana tipu fruit fibers exhibit significant degradation, with compositional dependence (cellulose–hemicellulose–lignin ratio) influencing biodegradation kinetics^106,108	Wool demonstrates substantial biodegradation in soil, aqueous, and aerobic composting environments, comparable to or exceeding that of PLA and cotton^104,105
Cytocompatibility	Generally high cytocompatibility owing to chemical inertness and absence of toxic degradation products; suitability for biomedical use can be further enhanced through surface modification^109	Excellent cytocompatibility and bioactivity, particularly for silk fibroin and keratin, supporting extensive application in tissue engineering and regenerative medicine^110
Antimicrobial potential	Limited intrinsic antimicrobial activity; performance is highly tunable through chemical functionalization or incorporation of antimicrobial agents^109	Typically lacks strong inherent antimicrobial activity; functional modification is required to impart antimicrobial behavior^110
Additional biological functions	Effective biosorbents for metal ions due to abundant hydroxyl and carboxyl functional groups; also used as bio-reinforcement in microbially enhanced self-healing composites^110	Suitable for engineered bio-composites with tailored biological and mechanical properties; allergenic responses depend largely on fiber morphology and processing rather than intrinsic chemistry^110

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3.3 Chemical properties

The chemical composition of natural fibers largely determines their physical, mechanical, and interfacial behavior in textile and composite applications. Natural fibers are complex biopolymers composed primarily of cellulose, hemicellulose, lignin, pectin, waxes, and minor extractives, as shown in Table 4, with their relative proportions varying according to the botanical source, growth conditions, and extraction method.¹¹¹ Cellulose, a linear polysaccharide of β-D-glucopyranose units, forms the main structural framework and contributes to high tensile strength, stiffness, and dimensional stability through extensive intra- and intermolecular hydrogen bonding.¹¹² The degree of polymerization and crystallinity of cellulose significantly affect the mechanical and sorption behavior of fibers.¹¹³ Hemicellulose, an amorphous matrix of short-chain polysaccharides, binds microfibrils together and influences flexibility and hydrophilicity, although its low thermal and biological stability makes fibers more susceptible to moisture absorption and microbial degradation.¹¹⁴ Lignin, a three-dimensional phenolic polymer, acts as a cementing material that provides rigidity, ultraviolet resistance, and protection against microbial attack; however, high lignin content generally reduces flexibility and spinnability.^115,116 Pectin and surface waxes determine fiber smoothness and dyeability, and their partial removal during retting or alkali treatment improves adhesion and wettability in subsequent processing.¹¹⁷

Table 4 Chemical composition of natural fibers

Fiber	Hemicellulose (wt%)	Cellulose (wt%)	Lignin (wt%)	Ref.
Bamboo	30	26–43	21–31	118
Coir	0.15–0.25	32–43	40–45	119
Date palm	18–25	41–46	20–27	120
Banana	38.54	43.46	9	121
Bagasse	16.8	55.2	25.3	122
Abaca	20–25	56–63	7–9	123
Jute	14–20	61–71	12–13	124
Sisal	—	65	9.9	122
Hemp	15	68	10	125
Ramie	13–16	68.6–76.2	0.6–0.7	126
Flax	18.6–20.6	71	2.2	126
Kenaf	20.3	72	9	120
Pineapple	—	81	12.7	118
Cotton	5.7	82.7–90	<2	124

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Typical compositional ranges reported in literature indicate that cotton contains about 88–96% cellulose with minimal lignin (<1%), jute and hemp contain 60–70% cellulose, 15–22% hemicellulose, and 8–12% lignin, while coir is distinguished by a low cellulose fraction (32–43%) but exceptionally high lignin content (40–45%), conferring remarkable durability and water resistance.¹²⁵ Recent studies further demonstrate variability within plant fibers; for example, Ficus racemosa fibers contain 72.36 wt% cellulose, 11.21 wt% hemicellulose, and 10.45 wt% lignin, while Acacia arabica fibers exhibit 68.61 wt% cellulose, 15.63 wt% hemicellulose, and 9.47 wt% lignin.^127,128 Similarly, Ficus carica bark fibers show 62.1 wt% cellulose, 12.3 wt% hemicellulose, and 9.6 wt% lignin, confirming that differences in botanical origin significantly influence chemical composition and, consequently, fiber performance.¹²⁹ The density of these fibers also reflects compositional variation, with Ficus racemosa fibers exhibiting a density of approximately 895 kg m⁻³.¹²⁷ Protein-based fibers such as wool and silk differ fundamentally, being composed almost entirely of keratin and fibroin proteins, respectively, whose peptide linkages and sulfur cross-bridges dictate their elasticity and resistance to deformation.¹³⁰

The abundance of hydroxyl groups in cellulose and hemicellulose renders most plant fibers chemically reactive, enabling surface modification through alkali treatment, silane coupling, acetylation, or grafting reactions that enhance compatibility with hydrophobic polymer matrices. While such treatments improve adhesion and reduce moisture affinity, the fibers remain sensitive to strong acids and oxidizing agents that can cleave glycosidic bonds and reduce molecular weight.¹³¹ These compositional differences clearly distinguish plant fibers rich in polysaccharides from protein-based animal fibers and inorganic mineral fibers, which lack reactive hydroxyl groups and therefore require different modification strategies or are unsuitable for chemical functionalization in composite systems. The chemical characteristics of natural fibers govern their intrinsic performance, such as strength, durability, and dyeability, and also dictate their processing behavior and environmental stability, making chemical composition a critical factor in designing fibers for advanced textile and composite applications.¹³²

3.4 Thermal properties

The thermal properties of natural fibers are critical in determining their processing behavior, dimensional stability, and suitability for textile and composite applications. In general, cellulosic fibers such as cotton, flax, jute, hemp, and sisal display limited thermal stability, with degradation typically beginning around 220–250 °C, corresponding to the breakdown of hemicellulose and amorphous cellulose regions, followed by major mass loss between 300–350 °C due to cellulose decomposition.¹³³ The residual char formation above 400 °C is mainly attributed to lignin, which decomposes over a broader temperature range (200–500 °C) because of its aromatic, cross-linked polymeric structure.^134,135 The higher the lignin content, as in coir fiber, the greater the char yield and thermal resistance, which enhances its performance in thermal insulation and composite reinforcement applications. Conversely, low-lignin fibers like cotton tend to ignite easily and produce minimal char residue. In contrast, mineral-based fibers exhibit superior thermal stability compared to plant- and animal-derived fibers, as organic constituents such as cellulose, hemicellulose, lignin, and proteins typically degrade between 200 and 300 °C, whereas mineral fibers can withstand temperatures exceeding 500 °C due to their crystalline silicate structures and strong ionic or covalent bonding.^136,137

Thermal conductivity and heat capacity of natural fibers are generally low, ranging between 0.04 and 0.06 W m⁻¹ K⁻¹, making them excellent thermal insulators for protective clothing and building textiles.¹³⁸ Moisture content plays a significant role, as absorbed water acts as a heat sink and influences the specific heat capacity and thermal diffusivity of fibers. The crystalline regions of cellulose resist thermal motion, while amorphous regions soften earlier, leading to shrinkage and loss of mechanical integrity under high temperatures.¹³⁹ For mineral-based fibers, thermal conductivity is influenced by parameters such as density, fiber diameter, and operating temperature. Basalt fiber insulation materials, for example, exhibit thermal conductivity values ranging from approximately 0.038 to 0.053 W m⁻¹ K⁻¹ at mean temperatures between 100 °C and 400 °C, with temperature having a more pronounced effect than density.^140,141 Basalt fiber insulation with densities of 50 and 150 kg m⁻³ shows only minor differences in thermal conductivity at equivalent temperatures, indicating that heat transfer behavior is primarily temperature-dependent.¹⁴⁰ The inherently porous and fibrous structure of mineral fibers contributes significantly to their low thermal conductivity by trapping air within the material, which impedes heat transfer through conduction, convection, and radiation. In such porous insulation systems, total thermal conductivity is governed by the combined contributions of solid conduction, convective heat transfer, and radiative transfer (k = k_c + k_conv. + k_r).¹⁴²

In the case of protein-based fibers, silk exhibits thermal degradation around 280–290 °C due to peptide bond cleavage in fibroin,¹⁴³ while wool begins to degrade near 200 °C as disulfide linkages in keratin are disrupted, releasing sulfur-containing volatiles.¹⁴⁴ This comparatively lower thermal stability limits the use of animal fibers in high-temperature environments but supports their application in thermal insulation and comfort-related textiles. Thermal analysis techniques such as Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) are widely used to characterize these behaviors, providing insight into the degradation kinetics and activation energy of different fiber types. Mineral fibers such as basalt have also been extensively studied using thermal diffusivity measurements, including infrared thermography, particularly in basalt fiber–reinforced polymer composites.¹⁴⁵

Basalt fibers further enhance thermal insulation performance when incorporated into composite and construction materials. Studies have shown that basalt fiber additions improve thermal insulation in foamy kaolinite-based composites, autoclaved aerated concrete, and conventional concrete mixtures, contributing to improved energy efficiency in buildings. For instance, basalt fiber–reinforced concrete has demonstrated thermal conductivity values as low as 0.283 W m⁻¹ K⁻¹ at a fiber content of 15%, highlighting its potential for energy-efficient structural applications.¹⁴⁶

3.5 Morphological properties

The morphological characteristics of natural fibers play a vital role in determining their physical, mechanical, and interfacial performance in textile and composite applications. These fibers possess a complex hierarchical structure comprising multiple layers such as the primary wall, secondary wall, and lumen, which together define their surface topology, crystallinity, and overall mechanical behavior.¹⁴⁷ The outer primary wall, rich in pectin and waxes, contributes to surface smoothness and protection, while the secondary wall, composed mainly of cellulose microfibrils embedded in a hemicellulose–lignin matrix, governs the fiber's strength and stiffness.¹⁴⁸ The microfibrillar angle (MFA), representing the orientation of cellulose microfibrils relative to the fiber axis, is a crucial structural parameter; smaller angles (5–10°),¹⁴⁹ as observed in flax and hemp, lead to higher tensile strength and stiffness, whereas larger angles in jute or coir result in improved flexibility but lower modulus.¹⁵⁰ The lumen, a central hollow channel running along the fiber axis, varies in size among fiber types and influences density, moisture absorption, and thermal insulation behavior.¹¹¹

Microscopic observations using Scanning Electron Microscopy (SEM) reveal that plant fibers generally exhibit rough and uneven surfaces with varying porosity and fibrillation, which significantly influence fiber–matrix adhesion and dye uptake.¹⁵¹ Cotton fibers show a convoluted ribbon-like structure with natural twists, flax and hemp have polygonal cross-sections with well-defined lumens,¹⁵² while coir fibers exhibit thick cell walls and narrow lumens contributing to higher rigidity.¹⁵² Protein-based fibers display distinct morphologies; wool has overlapping cuticle scales responsible for felting and frictional behavior, whereas silk filaments exhibit a smooth and continuous surface giving rise to excellent luster and drape.¹⁵³ Techniques such as X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) are widely used to analyze crystalline orientation and molecular arrangement, confirming that most plant-based fibers possess a semi-crystalline structure dominated by cellulose I polymorph. The degree of crystallinity, which generally ranges between 50–80% depending on fiber type and treatment, directly affects tensile strength, dimensional stability, moisture regain, and dyeing properties.¹⁵⁴ Thus, the morphological architecture and microstructural parameters of natural fibers are fundamental to understanding their performance and optimizing their processing for textile and composite applications.

4 Classification of natural fibers

4.1 Based on origin

This Fig. 2 illustrates the classification of natural fibers according to their source into three primary groups: plant-based, animal-based, and mineral-based fibers.

Fig. 2 Classification of natural fibers based on origin.

4.1.1 Plant based fibers.
4.1.1.1 Bamboo. Bamboo is a fast-growing woody grass belonging to the Poaceae family and is widely distributed across tropical, subtropical, and temperate regions, particularly in Southeast Asia and South America.¹⁵⁵ Its rapid regeneration, high biomass yield, and broad availability make bamboo an important renewable lignocellulosic resource for construction, furniture, textiles, and related applications. Bamboo fibers are mainly extracted from the culm, as shown in Fig. 3, and consist predominantly of cellulose, hemicellulose, and lignin, which together account for more than 90% of the dry weight, while minor constituents such as waxes, resins, tannins, proteins, and ash influence surface chemistry and processing behavior.¹⁵⁶ Fiber extraction is commonly achieved through chemical or mechanical routes; chemical processing involves alkali hydrolysis with sodium hydroxide followed by carbon disulfide treatment and bleaching, whereas mechanical processing relies on enzymatic decomposition and mechanical separation. Although the mechanical route requires higher labor and cost, it is regarded as environmentally preferable due to reduced chemical consumption.¹⁵⁷

Fig. 3 Schematic representation of the hierarchical structural organization of bamboo from the culm scale to the tissue level.

Bamboo fibers have been widely examined as reinforcing agents in asphalt mixtures because of their thermal stability and fibrous morphology. Sheng et al.¹⁵⁸ reported that bamboo fiber–reinforced dense-graded (DG) and stone matrix asphalt (SMA) mixtures maintained stability during mixing and compaction, with adequate moisture resistance confirmed by Marshall stability and freeze–thaw tests. Improvements in rutting resistance and low-temperature cracking resistance were observed, with optimal fiber contents of 0.2–0.3% for DG mixtures and 0.4% for SMA mixtures by total mixture weight. Xia et al.¹⁵⁹ further showed that bamboo fiber can substitute lignin fiber due to superior moisture and low-temperature stability, although lignin fiber exhibited slightly higher mechanical strength. The enhanced ductility and adhesion of bamboo fiber-modified asphalt were attributed to the rough fiber surface, oil absorption capacity, and relatively high density, which contribute to improved mixture flexibility and crack resistance. Laboratory aging studies indicated that bamboo fiber-modified asphalt exhibits stiffness and fatigue behavior comparable to polyester fiber systems.¹⁶⁰ However, the hydrophilic nature of bamboo can limit interfacial bonding with asphalt,¹⁶¹ prompting surface modification approaches such as melamine–formaldehyde copolymer treatment, which significantly improved tensile strength and stability, as confirmed by SEM evidence of enhanced fiber–matrix adhesion.¹⁶²

4.1.1.2 Coir. Coconut fiber, also known as coir fibre, is a lignocellulosic material obtained from the husk of coconuts, which are mainly cultivated in tropical regions, particularly in Southeast Asia. Based on color, it is divided into two types: white and brown coir. The white fibres are extracted from immature coconuts, while the brown ones are obtained from fully matured fruits, as shown in Fig. 4. According to Adeniyi et al.,¹⁶³ the chemical composition of coconut fibre includes cellulose (32–50%), hemicellulose (0.15–15%), lignin (30–46%), and pectin (3–4%), indicating that cellulose and lignin are its principal constituents, which provide durability, strength, and resistance to weather and water.¹⁶⁴ Moreover, coconut fibre has notable advantages such as low cost, low density, high elongation at break, and biodegradability.¹⁶⁵ Oda et al.¹⁶⁶ compared coconut fibre with other natural fibres such as sisal, cellulose, and polyester and observed that coconut and sisal fibres exhibited better strength and stability characteristics. Another research also confirmed that coconut fibre could effectively replace cellulose fibre due to its superior structural properties, though its stiffness can make composites more brittle.¹⁶⁷ In another investigation, Norhidayah et al.¹⁶⁸ used both coconut shells and fibres, where the shells partially replaced coarse aggregates at varying percentages (0%, 5%, 10%, and 15%), and fibres were added at 0.3% and 0.5%. Because of their high absorption capacity, both materials were pre-treated with sodium hydroxide (NaOH) for one hour. The findings showed that combining 10% coconut shells with 0.3% coconut fibre significantly enhanced the stability and deformation resistance of the resulting material.

Fig. 4 Anatomical layers of the coconut highlighting the fibrous husk used for coir fiber extraction.

4.1.1.3 Jute. Jute is a bast fibre belonging to the Tiliaceae family and is primarily cultivated in countries such as India, Bangladesh, Pakistan, China, and Brazil.^169,170 It is widely utilized in textiles, construction, and automotive industries due to its fine texture, low thermal conductivity, and affordability.¹⁷¹ Similar to other natural fibres, jute mainly consists of cellulose, hemicellulose, and lignin.¹³ Fig. 5 shows the microstructure of jute fibre. Rashid et al.¹⁷² investigated the use of jute fibre as a reinforcing material, reporting that 0.5% and 1% fibre content increased stability by 29% and 10%, respectively, based on Marshall stability and flow tests, while the optimum binder content rose from 4% to 5%. The fibre-reinforced mixtures demonstrated improved deformation resistance, with 0.5% fibre identified as the most effective dosage. Ismael et al.¹⁷³ examined jute, polyester, and carbon fibres at varying proportions (0.25%, 0.5%, and 0.75%) and lengths (5, 7.5, and 10 mm) through drain-down, Marshall, and wheel tracking tests. Their results showed that all fibres enhanced rutting resistance and mixture stability, particularly at 0.5% content and 7.5 mm length. Carbon fibres exhibited the highest improvement (53% in rutting resistance and 100% in dynamic stability), followed by polyester and jute fibres (34% and 63%, respectively), while jute fibres offered the best drain-down performance. In addition to their application in hot mix mixtures, jute fibres have also been successfully incorporated into warm mix¹⁷⁴ and cold mix¹⁷⁵ systems. For warm mix applications, the inclusion of jute fibres significantly enhanced fracture resistance under Mode I (tensile opening), indicating an improvement in tensile strength, with the optimal fibre content identified as 0.3% by total mixture weight.

Fig. 5 Morphological structure of jute fiber.

4.1.1.4 Sisal. Sisal fibre is a natural leaf fibre extracted from the sisal plant, a flowering species native to southern Mexico but now cultivated widely across tropical and subtropical regions. The extraction of sisal fibre is generally carried out using two primary techniques: retting followed by scraping, or mechanical decortication.¹⁷⁶ Among these, mechanical extraction tends to yield fibres of superior quality. The chemical composition of sisal fibre varies depending on the maturity of the plant; however, several studies¹⁷⁷ have identified cellulose, hemicellulose, and lignin as its principal constituents, with cellulose being the most abundant. Owing to its low cost, light weight, high tensile strength, and considerable stiffness,²¹ sisal fibre has found applications in various industries, including the manufacture of paper, textiles, carpets, ropes, and geotextiles, as well as in composite and construction materials. The performance of sisal fibre-reinforced materials largely depends on the fibre length and content. Ramalingam et al.¹⁷⁸ examined the influence of fibre lengths (5, 10, 15, and 20 mm) and contents (0.05%, 0.1%, 0.2%, and 0.3%) on the mechanical behaviour of mixtures and observed that a small addition of sisal fibre enhanced fatigue resistance and moisture durability, while excessive amounts reduced mixture stability. The best performance was achieved with 15 mm fibres at a concentration of 0.05% and an optimum binder content of 5.4%. Kar et al.¹⁷⁹ evaluated sisal fibre as a stabilizing additive in stone mastic and dense-graded mixtures, reporting that fibre inclusion increased Marshall stability and tensile strength while reducing flow value, air voids, and drain-down. Comparatively, mixtures with 0.3% sisal fibre exhibited superior mechanical characteristics in stone mastic asphalt (SMA) than in dense-graded ones. Sisal fibre has been used in SMA mixtures containing asphalt rubber binders, where both natural fibres demonstrated better improvements in tensile strength and resilient modulus compared to polyester and cellulose fibre-reinforced counterparts.¹⁶⁶ Fig. 6 represented the structure of sisal fiber.¹⁸⁰

Fig. 6 Structure of sisal fiber.

4.1.1.5 Cotton. Cotton fiber is a single-celled extension of the seed epidermis of the cotton plant (Gossypium genus), and it stands as the most economically significant natural textile fiber globally. It is primarily composed of cellulose, constituting approximately 88–96% of its dry weight, with the remainder consisting of proteins, waxes, and pectin.¹⁸¹ The unique properties of cotton fiber, such as its softness, absorbency, spinnability, dyeability, and comfort, contribute to its widespread use in textiles, hygiene products, and medical applications.¹⁸² The development of cotton fibers involves staged differentiation, including primary cell wall synthesis during elongation and subsequent secondary wall thickening, during which nearly pure cellulose is synthesized.¹⁸¹ The cellulose synthase complex (CSC), particularly the GhCesA 4, 7, and 8 subunits, plays a pivotal role in synthesizing and assembling cellulose into cell wall microfibrils, forming a 36-mer-like supercomplex during secondary cell wall synthesis.¹⁸³ These microfibrils, along with elementary fibrils, constitute the structural components of the cell wall, influencing the fiber's strength and rigidity, as shown in Fig. 7.

Fig. 7 Hierarchical structure of cotton cellulose from the cell wall to the molecular level, showing cellulose fibrils organized into microfibrils and elementary fibrils with crystalline and amorphous regions.

4.1.1.6 Ramie. Ramie (Boehmeria nivea L.) is a perennial herbaceous plant valued for its strong bast fibers, often referred to as the “king of natural fibers”.¹⁸⁴ This natural fiber possesses several desirable characteristics including attractive luster, high tenacity, enhanced strength, good microbial resistivity, and excellent moisture absorption, breathability, and antibacterial properties.¹⁸⁵ These attributes make ramie a significant raw material for the textile industry and a promising candidate for various composite applications, offering a sustainable alternative to synthetic fibers.¹⁸⁶ However, raw ramie fibers are tightly bound by gummy substances, which primarily consist of pectin, hemicellulose, and lignin. These non-cellulosic components must be removed through a process called degumming to separate the cellulose fibers and unveil their unique properties for textile and industrial applications.^184,187 The efficiency of gum removal directly impacts the quality and end-use potential of ramie fibers.¹⁸⁸ Fig. 8 illustrated the hierarchical organization of ramie fiber.

Fig. 8 Structural representation of ramie fiber.

4.1.1.7 Kenaf. Kenaf (Hibiscus cannabinus L.) is a fast-growing annual bast fiber plant belonging to the Malvaceae family, cultivated mainly in tropical and subtropical regions such as India, Bangladesh, Thailand, and parts of Africa.¹⁸⁹ It has emerged as one of the most promising renewable fibers due to its high yield potential (up to 6–10 t ha⁻¹) and short cultivation period of 4–5 months.¹⁹⁰ The composition of kenaf gives the fiber a combination of low density (1.2–1.4 g cm⁻³), high specific strength, and moderate stiffness, making it suitable for both textile and composite applications.¹⁹¹ The cellulose microfibrils in kenaf are oriented at a low microfibrillar angle (around 7–10°),¹⁹¹ which contributes to its high tensile strength, typically ranging from 400–800 MPa, and Young's modulus of 20–60 GPa, depending on extraction method and maturity stage.¹⁹²

Morphologically, kenaf fibers are multicellular and polygonal in cross-section, with a rough surface texture that promotes interfacial adhesion in polymer composites. The lumen structure enhances moisture sorption and improves comfort properties when used in apparel or home textiles. However, the high hydrophilicity and presence of hemicellulose can lead to poor dimensional stability and reduced fiber–matrix compatibility, often mitigated by surface modification techniques such as alkali treatment, silane coupling, or acetylation.¹³¹ In addition to conventional textile uses such as ropes, canvas, and coarse fabrics, kenaf is now widely used in automotive interior panels, packaging materials, paper pulp, and geotextiles, reflecting its versatility and environmental appeal.¹⁹³ Thermogravimetric studies indicate decomposition onset near 230–250 °C, which is adequate for most textile finishing and thermoplastic composite processing.¹⁹⁴ With its favorable strength-to-weight ratio, biodegradability, and CO₂ sequestration potential, kenaf has gained attention as a sustainable alternative to synthetic fibers and a significant contributor to the development of eco-friendly textile and industrial materials.

4.1.1.8 Kapok. Kapok fiber, obtained from the fruits of Ceiba pentandra, is a plant-based seed fiber widely recognized for its distinctive hollow morphology and extremely low density, and is primarily cultivated in tropical regions, with Indonesia contributing approximately 85% of global supply.¹⁹⁵ The fibers are unicellular, non-lignified trichomes characterized by a cylindrical lumen occupying 80–90% of the cross-sectional area, with typical lengths of 10–35 mm and diameters of 10–25 µm, resulting in a very low density of 0.03–0.05 g cm⁻³.^196–198 The smooth fiber surface is coated with a thin wax layer, in contrast to bast fibers that show nodes or convolutions, which imparts inherent hydrophobic and oleophilic behavior.¹⁹⁹ FIB-SEM analysis confirms tubular wall thicknesses of 806.1–863.3 nm and hollow ratios of 82.40–85.56%.¹⁴⁶ Chemically, kapok consists mainly of cellulose, hemicellulose, and lignin, with a wax fraction of 0.5–2.0% containing hydrophobic compounds such as bis(2-ethylhexyl) phthalate and N,N-dimethyldodecanamide; surface treatments using ethanol or sodium hydroxide remove non-cellulosic components, increase surface polarity, and improve fiber–matrix adhesion.^200,201

The pronounced hollow structure governs kapok's functional behavior, providing exceptional buoyancy and air-trapping capability but limiting tensile strength (3–8 MPa) and modulus (20–60 MPa) compared with bast fibers such as flax (345–1500 MPa).^198,202 This structural configuration defines kapok as a low-load-bearing fiber, where performance is dominated by insulation, absorption, and lightweight functionality rather than stiffness or strength. Surface-modified kapok fibers show improved interfacial bonding in composite systems, indicating that performance can be tailored when required, although fiber orientation and lumen preservation remain critical factors.²⁰³ The same hollow morphology results in low thermal conductivity (0.033–0.040 W m⁻¹ K⁻¹) and high acoustic damping due to immobilized air within the lumen.¹⁹⁸ In addition, the hydrophobic and oleophilic surface enables oil sorption capacities of 30–50 times the fiber's own weight, confirming kapok's classification as a functional fiber suited to absorption- and insulation-dominated roles rather than structural reinforcement.²⁰⁴ Consequently, kapok represents a distinct category of natural fibers where morphology-driven functionality outweighs mechanical performance, complementing bast fibers within a classification framework based on application-relevant fiber attributes.

4.1.1.9 Flax. Flax fiber, obtained from the stem of Linum usitatissimum L., is a plant-based bast fiber widely valued for its high mechanical performance and sustainable profile. Bast fibers, including flax, hemp, jute, kenaf, and ramie, are extracted from the outer cell layers of dicotyledonous plant stems.²⁰⁵ Flax fiber extraction typically involves retting, a microbiological process that partially degrades stem tissues, followed by mechanical separation of long cellulosic fibers; traditional dew retting remains widely practiced, although process optimization is ongoing to improve fiber quality and consistency.²⁰⁶ Chemically, flax consists mainly of cellulose and hemicellulose with relatively low lignin content, along with minor pectin (1–2%) and ash (<1%). The high cellulose and low lignin content distinguish flax from wood fibers, which generally contain 25–30% lignin, contributing to superior specific mechanical properties and greater ease of chemical functionalization.²⁰⁷ Cellulose microfibrils in flax exhibit axial stiffness on the order of 100–150 GPa, exceeding that of aluminum, which underpins its performance in technical applications and phytoremediation.²⁰⁸

The hierarchical cell-wall structure governs flax's mechanical behavior, with the thick S2 secondary layer dominating performance due to cellulose microfibrils aligned at a low microfibrillar angle of 4–10° relative to the fiber axis.²⁰⁹ This arrangement enables efficient axial load transfer, resulting in tensile modulus values of 50–80 GPa and tensile strength ranging from 500 to 1500 MPa, among the highest reported for natural fibers.²¹⁰ Flax fibers typically exhibit diameters of 12–25 µm, crystallinity indices of 65–75%, and moderate moisture regain of about 12% at 65% relative humidity, reflecting their hydrophilic nature associated with abundant surface hydroxyl groups.²⁰⁷ While hydrophilicity can reduce interfacial adhesion with hydrophobic polymer matrices, it facilitates surface treatments such as alkali, silane, or enzymatic modification, improving fiber–matrix bonding in composites.²¹¹ Thermally, flax fibers degrade in two stages, with hemicellulose decomposition at 200–260 °C and cellulose pyrolysis at 260–350 °C, and degradation onset above 220 °C, allowing compatibility with thermoplastics such as polypropylene and polylactic acid.^212,213 Applications of flax span linen textiles, ropes, and geotextiles to lightweight biocomposites for automotive and construction sectors, where flax fiber–reinforced systems have shown mechanical performance comparable to synthetic fiber composites following surface treatment. Compared with other bast fibers, flax offers a balanced combination of strength, fineness, and processability, while hemp provides higher elongation, ramie higher strength but lower flexibility and more demanding processing, and jute and kenaf generally lower tensile strength.^205,214 As a result, flax remains a benchmark bast fiber for high-performance lignocellulosic composite development.

4.1.2 Animal based fibers.
4.1.2.1 Feather fibers. The poultry industry generates a substantial amount of waste, with approximately 4 billion pounds of feather waste produced annually in the United States and more than 20 billion chickens slaughtered worldwide each year.²¹⁵ This accumulation poses environmental and health concerns, prompting growing interest in the valorization of chicken feather fibers (CFFs) as sustainable materials for composite applications, as illustrated in Fig. 9. CFFs are characterized by low density, high specific strength, and favorable thermal and acoustic insulation properties, making them suitable for lightweight and energy-efficient systems.²¹⁶ Chemically, CFFs consist of about 91% keratin protein, 1% lipids, and 8% water, with amino acids cross-linked through disulfide and hydrogen bonds that impart mechanical integrity, chemical resistance, and durability.²¹⁷ Structurally, feathers exhibit a hierarchical architecture comprising a central rachis with branched barbs and barbules, forming a keratin-based matrix with a honeycomb-like morphology that contributes to stiffness, flexibility, and effective sound and thermal insulation.²¹⁸

Fig. 9 Structure of chicken feather fiber.

The feasibility of incorporating CFFs into polymer composites has been demonstrated in several studies. Winandy et al.²¹⁹ reported that feather fibers in wood-based composites led to a moderate reduction in stiffness but significantly improved water resistance due to the hydrophobic nature of keratin. Zhan et al.²²⁰ identified considerable variability in the tensile strength and modulus of feather barbs, enabling tailored composite design. Huda et al.²²¹ showed that quill–polypropylene composites achieved higher noise reduction coefficients than jute-based systems, attributed to hollow quill structures and trapped air pockets, and further reported that hybrid polypropylene composites containing feather, recycled pulp, and kenaf fibers exhibited positive stiffness contributions from feather fibers, albeit lower than those of pulp fibers. Amieva et al.²²² found that polypropylene composites with 5–10 wt% quill fibers optimized load transfer and dynamic storage modulus, whereas higher fiber contents resulted in matrix overloading. Cheng et al.²²³ demonstrated that injection-molded CFF/polylactic acid composites exhibited improved tensile modulus, storage modulus, and thermal stability compared with neat PLA, indicating effective reinforcement and interfacial adhesion. Surface modification using hydrogen peroxide, sodium hydroxide, or potassium hydroxide has further improved tensile and physicochemical properties by removing surface impurities and exposing reactive keratin sites, while Barone et al.²²⁴ reported enhanced yield stress and elastic properties in CFF/low-density polyethylene composites, supported by SEM evidence of improved fiber–matrix bonding.

4.1.2.2 Silk. Silk is a protein-based natural fiber whose performance is governed by the molecular organization of fibroin. Bombyx mori (mulberry silk) is the most widely used form and consists mainly of fibroin and sericin, where fibroin constitutes the load-bearing filament core and sericin functions as an outer adhesive layer that is removed during processing to improve softness, luster, and dye affinity.²²⁵ Silk fibroin is a semi-crystalline protein polymer rich in glycine, alanine, and serine, forming β-sheet crystallites that impart tensile strength and stiffness, interspersed with amorphous domains that provide flexibility and extensibility.²²⁶ This hierarchical arrangement underpins silk's balance between strength and deformability. Spider dragline silk from Nephila species represents the upper performance limit among natural fibers, with tensile strength approaching 1.5 GPa and elongation exceeding 40%, resulting from β-sheet nanocrystals embedded in an amorphous protein matrix.^227–229 These properties remain stable up to approximately 150 °C, while at subzero temperatures extensibility increases to about 45% without loss of tensile strength. In comparison, mulberry silk exhibits lower tensile strength, around 0.6 GPa, combined with resistance to mild acids, insolubility in most organic solvents, and low water uptake due to its compact crystalline structure, although its amorphous regions remain susceptible to hydrolytic degradation under prolonged acidic conditions.²³⁰ Structurally, the fibroin heavy chain comprises twelve alternating crystalline and amorphous domains, enabling controlled load transfer and elastic recovery.²³¹

Chemical and enzymatic modifications are commonly employed to adjust silk fibroin performance while preserving its protein backbone. Enzymatic grafting of acrylic acid using an H₂O₂–HRP system increases mechanical strength through controlled surface functionalization,²³² while tyrosinase-catalyzed chitosan grafting improves strength and crease resistance via covalent bonding with oxidized tyrosyl residues on fibroin.²³³ Degradation studies consistently show preferential breakdown of amorphous regions, whereas β-sheet-rich crystalline domains remain stable, allowing predictable changes in mechanical response over time.²³⁴ Carbodiimide-mediated grafting further enhances fibroin reactivity and network stability through self-crosslinking and TyrP-bridged structures.²³⁵ These characteristics position silk as a high-toughness, protein-based natural fiber, distinct from lignocellulosic fibers, and suited to applications where flexibility, strength retention, and molecular stability are required rather than bulk structural reinforcement. Fig. 10 illustrates the hierarchical structure of silk fiber.

Fig. 10 Structure of silk fiber.

4.1.2.3 Wool. Wool fibers are composed of keratin with a complex hierarchical structure, as illustrated in Fig. 11, where components with different properties combine to achieve functional performance.²³⁶ A single wool fiber is a heterogeneous biomaterial consisting of three main layers: the outer cuticle with overlapping scales, the cortex forming the primary load-bearing region, and the medulla, which may be continuous, fragmented, or absent depending on fiber type.²³⁷ Keratin in wool is largely insoluble in water, organic solvents, and dilute acids or alkalis due to tightly packed α-helical and β-sheet structures cross-linked by disulfide and hydrogen bonds, which impart chemical stability and resistance to degradation.²³⁸ Wool fiber diameter varies significantly among sheep breeds, ranging from 11.5 to 47 µm, which governs its suitability for apparel or interior textile applications.²³⁹ The amino acid composition, rich in cystine, serine, glutamic acid, and glycine, contributes to strength and flexibility through intermolecular bonding. Wool exhibits limited dimensional change during rewetting or swelling, typically 1–2%, due to the resistance of paracrystalline filaments. Its protein-based structure allows wool to absorb moisture up to 33% of its dry mass without feeling damp, a property attributed to hydrogen bonding within amorphous regions while crystalline domains remain largely impermeable. For fibers with approximately 25% crystallinity, the amorphous matrix alone can absorb water equivalent to about 45% of the dry weight.²⁴⁰ Sheep remain the primary source of keratin fibers for textiles, with fine wool used for clothing and coarser grades for carpets, upholstery, and insulation. Studies on wool as a building insulation material show thermal conductivity and insulation performance comparable to, or better than, mineral- and rock-based insulations.²⁴¹ Surface modification approaches have been explored to extend wool's functionality; plasma treatment using oxygen, argon, nitrogen, or air removes the surface fatty acid layer, improving wettability and adhesion, as confirmed by SEM analysis.²⁴² Enzymatic modification using transglutaminase has also been shown to enhance tensile strength and improve the stability of wool-derived keratin films in phosphate-buffered saline and simulated gastric fluid by promoting covalent cross-linking between protein chains.²⁴³

Fig. 11 Schematic structure of wool fiber. This figure has been reproduced from ref. 244 with permission from SAGE Publications, copyright 2026.

4.1.2.4 Human hair. Human hair, an abundant yet often underutilized non-biodegradable waste material, has recently gained attention as a potential reinforcement fiber for bio-composite and engineering applications. Despite being discarded in large quantities worldwide, human hair exhibits favorable mechanical properties, including a surface tensile strength ranging from 150 to 220 MPa, making it a strong and flexible natural fiber. The primary component of human hair is keratin, a fibrous structural protein composed of long chains of amino acids forming high-molecular-weight polymers.²⁴⁵ These keratin proteins constitute approximately 65–95% by weight of the total fiber mass and are responsible for its mechanical strength, flexibility, and chemical resistance. Fig. 12 illustrates the key structural components of human hair fiber, including the cuticle, cortex, and medulla, which collectively contribute to its performance characteristics.²⁴⁶

Fig. 12 Structural components of hair fiber. This figure has been reproduced from ref. 247 with permission from MDPI, copyright 2016.

The reinforcing potential of human hair in polymer composites has been demonstrated in several studies. Rao et al.²⁴⁸ investigated polyester composites reinforced with human hair at different fiber volume fractions and observed that lower fiber contents led to intra-fiber voids, whereas higher contents resulted in inter-fiber voids, highlighting the importance of fiber dispersion and interfacial bonding. An optimal fiber volume fraction yielded a maximum tensile strength of 23.5 MPa, confirming that processing conditions strongly influence composite performance. The combination of rigidity and flexibility associated with cortex keratin makes human hair suitable for applications requiring impact resistance and ductility.²⁴⁹ Hair properties are further influenced by intrinsic and extrinsic factors such as amino acid composition, age, environmental exposure, and chemical treatments, as thermal and mechanical stresses can alter hydrogen bonding and disulfide linkages within the α-helical keratin structure.²⁴⁰ While the cortex governs tensile response, non-keratin components of the cuticle and the cell membrane complex contribute to fiber cohesion and resistance to surface wear during grooming and mechanical loading.²⁵⁰ The amino acid profile of human hair, shown in Fig. 13, reflects the dominance of amino acids responsible for structural stability, elasticity, and moisture-binding behavior.

Fig. 13 Distribution of amino acids based on their relative abundance.

4.1.3 Mineral based fibers.
4.1.3.1 Asbestos. Asbestos is a naturally occurring silicate mineral fiber historically recognized for its fibrous morphology, high tensile strength, chemical inertness, and exceptional resistance to heat and fire.²⁵¹ It represents a classical example of mineral-based natural fibers and was extensively used in industrial applications during the 20th century. Asbestos fibers are grouped into two mineral families, namely serpentine and amphibole.²⁵² The serpentine group consists mainly of chrysotile (white asbestos), characterized by curly and flexible fibers, while the amphibole group includes amosite, crocidolite, tremolite, anthophyllite, and actinolite, which exhibit straight, needle-like, and more brittle morphologies.^253,254 Chemically, chrysotile is composed of hydrated magnesium silicate (Mg₃Si₂O₅(OH)₄), whereas amphibole asbestos contains calcium–magnesium–iron silicates.²⁵⁵ The fibrous habit originates from the crystalline arrangement of silica tetrahedra into chain-like structures that allow longitudinal splitting into fine fibrils.

Asbestos fibers exhibit very high tensile strength, typically in the range of 700–3000 MPa, thermal stability up to approximately 1000–1200 °C, and strong resistance to most acids and alkalis.²⁵¹ Their density ranges from 2.2 to 2.7 g cm⁻³ depending on mineral type.²⁵⁶ The extremely high aspect ratio, often exceeding 100 : 1, enabled efficient stress transfer and underpinned their historical use in cement composites, insulation materials, brake linings, roofing sheets, gaskets, and friction products.²⁵⁷ Chrysotile asbestos accounted for nearly 90% of global consumption due to its flexibility, fine fibrillar structure, and strong interlocking capability with cementitious and polymer matrices, resulting in improved strength, dimensional stability, and heat resistance.

The thermal and acoustic insulation performance of asbestos arises from its low thermal conductivity, high specific surface area, and porous fibrous network, which made it effective in high-temperature environments. However, due to its well-established health risks, including severe respiratory diseases associated with fiber inhalation, asbestos mining, processing, and use have been banned or strictly regulated in many regions.²⁵⁸ Consequently, research has shifted toward safer alternative mineral fibers such as basalt, wollastonite, and sepiolite that aim to replicate asbestos-like thermal endurance and mechanical performance without associated health hazards.²⁵⁹ Despite its prohibition, asbestos remains a benchmark mineral fiber in materials science, serving as a historical reference point for evaluating and designing non-toxic inorganic reinforcements with comparable durability and heat resistance.

4.1.3.2 Wollastonite. Wollastonite is a naturally occurring calcium silicate mineral (CaSiO₃) that crystallizes in a triclinic structure and typically develops as acicular or needle-like crystals during the metamorphism of siliceous limestone.²⁶⁰ It is a non-toxic mineral-based natural fiber known for its fibrous morphology, excellent mechanical strength, and high chemical and thermal stability.¹¹¹ The fibers of wollastonite generally have diameters ranging from 2 to 20 µm and lengths between 10 and 100 µm, with aspect ratios of 5 : 1 to 20 : 1, depending on the refining process.^261,262 Wollastonite exhibits a density of about 2.9 g cm⁻³, tensile strength of 20.45 MPa, and a bending strength is 38.02 MPa, placing it within the performance range of conventional inorganic fibers used in technical textiles.²⁶³

The acicular morphology of wollastonite fibers contributes significantly to their reinforcing behavior in textile composites and high-performance fabric structures.²⁶⁴ When incorporated into textile-reinforced polymer matrices or nonwoven technical textiles, wollastonite enhances dimensional stability, rigidity, and thermal resistance while maintaining low density and high whiteness.²⁶⁵ Its high aspect ratio enables efficient stress transfer within the fiber matrix, improving fabric stiffness, abrasion resistance, and durability under thermal and mechanical loading. The fibrous particles can also act as functional fillers in coated and laminated textiles, where they improve flame retardancy, UV resistance, and thermal shielding performance without compromising flexibility or texture.²⁶² In protective and industrial textiles, wollastonite fibers are used in combination with glass or aramid fibers to enhance the heat barrier properties of woven and nonwoven composites.²⁶⁶ Their high refractoriness and resistance to molten metal splashes also make them suitable for heat-protective suits, welding aprons, and furnace insulation cloths.

In addition to performance textiles, wollastonite fibers are being explored in eco-friendly fabric coatings and specialty nonwovens as mineral fillers or reinforcement materials that reduce flammability and improve dimensional integrity. Their natural whiteness and smooth surface allow uniform dispersion in polymeric textile coatings such as polyurethane (PU) and silicone matrices, enhancing heat stability and wear resistance of coated fabrics.²⁶⁷ Moreover, surface modification treatments, including silane coupling or acid etching, can be employed to improve the adhesion of wollastonite with organic binders and textile resins, leading to composites with enhanced mechanical and thermal behavior. These features make wollastonite an increasingly important functional mineral fiber in the development of advanced, sustainable technical textiles and heat-resistant fabric systems.²⁶⁸

4.1.3.3 Basalt. Basalt fiber (BF) is a high-performance inorganic fiber produced by melting and continuously extruding natural basalt rock, typically sourced from volcanic formations, at temperatures of approximately 1450–1500 °C.²⁶⁹ Owing to its geological origin and silicate-based composition, BF is classified as a mineral fiber, although it is frequently discussed alongside natural fibers in composite and sustainability studies.²⁶⁹ Unlike plant- or animal-derived fibers, BF is intrinsically inorganic and consists primarily of SiO₂, Al₂O₃, CaO, MgO, and iron oxides, with minor amounts of Na₂O, K₂O, and TiO₂, which contributes to its compatibility with cementitious systems.²⁷⁰ At the atomic level, BF is formed from interconnected silicon–oxygen tetrahedra that generate a chemically stable and non-fibrous structure, in contrast to the chain-like crystalline arrangements of amphibole asbestos responsible for its hazardous morphology.²⁷¹ Basalt fibers typically exhibit diameters in the range of 10–25 µm.²⁶⁹

Mechanically, BF exhibits very high tensile strength (approximately 3000–4840 MPa) and elastic modulus (70–95 GPa), exceeding those of many lignocellulosic fibers such as hemp and sisal and approaching the performance of E-glass fibers.²⁷⁰ These properties enable BF to significantly enhance compressive, flexural, and tensile behavior in cement-based and polymer composites, with optimal fiber contents improving strength, crack resistance, and durability.²⁷² Hybrid systems combining basalt fibers with natural fibers such as jute have further demonstrated synergistic reinforcement effects.²⁷⁰ Thermally, BF is non-combustible (LOI > 80%), remains dimensionally stable up to about 700 °C, and decomposes only above 1000 °C, making it far superior to organic fibers that degrade or ignite between 200 and 300 °C.^269,270 BF also shows good resistance to weak acids, salts, and weathering; however, limited alkali resistance in highly alkaline environments such as concrete has prompted the development of alkali-resistant basalt fibers and compositional modifications.²⁷³ These combined properties have led to widespread use of BF in construction (HPC, UHPC, ECC, recycled concrete), automotive and aerospace composites, fire-resistant insulation, gypsum and asphalt systems, and lightweight structural components.²⁷⁴ Importantly, BF is now recognized as a safer, environmentally friendly alternative to asbestos in high-temperature and insulation applications, offering comparable thermal and mechanical performance without the severe health risks associated with asbestos exposure.²⁷⁰

4.2 Based on application

Natural fibers can be classified according to their end-use applications, which reflect their intrinsic physical, mechanical, chemical, and aesthetic properties. The performance of a fiber in a particular textile product depends on parameters such as tensile strength, fineness, flexibility, moisture absorption, dye affinity, and comfort-related characteristics, as demonstrated in Table 5. Each category employs different fiber types and processing techniques to meet specific functional or aesthetic requirements.

Table 5 Application-based classification of natural fibers according to dominant functional attributes

Application class	Defining structural/chemical attributes	Representative fiber types	Functional mechanisms	Typical performance indicators
Structural load-bearing fibers	High cellulose crystallinity, low microfibril angle, aligned cellulose microfibrils, high axial stiffness	Flax, hemp, jute, kenaf, ramie	Efficient axial stress transfer through parallel cellulose microfibrils	High tensile strength, high modulus, low elongation
Thermal and acoustic insulation fibers	High hollowness, high porosity, low density, air-trapping morphology	Kapok, coir, luffa, wood fibers, wool, feather fibers	Suppression of heat conduction and convection, acoustic damping via trapped air	Low thermal conductivity, high sound absorption
Comfort and apparel fibers	Fine fiber diameter, low bending rigidity, moisture sorption and transport capability	Silk, cotton, merino wool, bamboo fibers	Soft handle, drape control, hygroscopic buffering, vapor transport	High softness, moisture regulation, skin comfort
Protective and high-temperature-resistant fibers	Thermal stability, flame resistance, chemical inertness, char-forming capability	Basalt fiber, wool, flame-retardant cotton, treated ramie	Resistance to heat and flame, char formation, flame-retardant surface chemistry	High limiting oxygen index, thermal stability, fire resistance
Sorption, filtration, and separation fibers	Controlled lumen size, surface chemistry, pore hierarchy	Kapok, modified cellulose fibers, agricultural residues	Capillary entrapment, selective permeation, affinity-based separation	High oil uptake, selective separation, filtration efficiency

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4.2.1 Load-bearing and structural natural fibers. Structural and load-bearing natural fibers are primarily represented by plant bast fibers such as flax, hemp, jute, kenaf, and ramie, which are distinguished from other natural fibers by their high specific stiffness and strength.²⁰⁵ These fibers share a common cell-wall architecture characterized by high cellulose crystallinity (often >70%) and a low microfibril angle, typically below 10°, resulting in cellulose microfibrils aligned nearly parallel to the fiber axis.^205,275 Compared with other plant fibers, this parallel alignment within a lignin–hemicellulose matrix enables more efficient axial stress transfer and underpins their classification as structural fibers.²⁰⁵

Within this group, flax is often used as a reference bast fiber due to its high tensile strength and stiffness, which arise from the highly crystalline and well-aligned cellulose microfibrils in the thick secondary walls of sclerenchyma cells.²⁷⁶ Hemp exhibits comparable load-bearing capability, combining high tensile strength with a relatively high Young's modulus, while kenaf and jute provide structurally useful reinforcement with greater sensitivity to processing conditions and moisture uptake, respectively.²⁷⁷ Across all bast fibers, lignin in the secondary wall acts as a natural binding phase, filling spaces between cellulose and hemicellulose to form a rigid, compression-resistant structure analogous to reinforced concrete, contributing to dimensional stability under moderate hygrothermal exposure.²⁰⁵

In contrast, most animal-derived fibers are excluded from this structural classification. Although silk fibers exhibit high toughness and β-sheet-driven crystallinity, limitations related to thermal stability above 150 °C, scalability, and interfacial compatibility restrict their use to specialized or hybrid reinforcement roles rather than primary load-bearing functions.²⁷⁸ Keratin-based fibers such as wool are similarly excluded due to low stiffness and high hygroscopicity. It is notable, however, that animal biological systems rely on collagen fibers within extracellular matrices to resist tensile loads, serving a structural role analogous to cellulose microfibrils in plant bast fibers.

Mineral fibers, particularly basalt fiber, form a separate class of load-bearing natural fibers. Unlike biologically derived fibers, basalt fiber is produced from molten basalt rock and exhibits homogeneous filament morphology, negligible moisture absorption, and high axial stiffness derived from strong Si–O and metal–oxygen bonding networks.²⁷⁹ When compared with bast fibers, basalt fiber offers superior thermal and chemical stability, long-term dimensional predictability, and creep resistance, positioning it alongside plant bast fibers in structural classifications while distinguishing it by durability and environmental robustness.²⁸⁰

4.2.2 Thermal and acoustic insulation natural fibers. Natural fibers classified for thermal and acoustic insulation are defined by structural features such as hollowness, high porosity, and low bulk density, which collectively promote air entrapment and limit heat transfer and sound propagation. Hollowness, referring to internal lumens within fibers, reduces solid-phase thermal conduction by replacing dense material with air, a poor heat conductor.¹⁴² Kapok fiber (Ceiba pentandra) represents the most pronounced example, exhibiting a tubular morphology with thin cell walls of approximately 806.1 nm and hollow ratios exceeding 85%, resulting in extreme lightness and effective thermal insulation.¹⁹⁶ Similar insulation behavior is observed in luffa fibers, whose sponge-like hollow structure enhances both thermal retention and acoustic damping,²⁸¹ and in bio-inspired fibrous systems modeled after polar bear hair, where internal air pockets dominate insulation performance.²⁸²

Porosity further governs this classification by describing void space generated within individual fibers and across fibrous assemblies. Highly porous networks trap air in interconnected pathways, suppressing convective heat transfer and dissipating sound energy through viscous and thermal losses. In kapok-based fibrous materials, sound absorption improves as porosity is optimized at low bulk density,²⁸³ while highly porous ligno-nanocellulosic foams demonstrate that ultralow density is closely linked to effective insulation.²⁸⁴ Low density therefore arises directly from the combined effects of hollowness and porosity, with extensive air voids reducing thermal conductivity by limiting the solid fraction available for heat conduction.¹⁹⁷ This air-trapping mechanism is further reinforced by tortuous fiber networks that restrict airflow and inhibit convective heat transport.

Within plant fibers, kapok is the most insulation-oriented due to its high hollowness, fineness, wax-coated surface, and hydrophobicity, enabling its use in nonwoven fabrics, composite aerogels, and blended systems with polymers or biopolymers such as polypropylene and chitosan.¹⁹⁷ Coir fibers, although less hollow, are highly lignified and form rigid open-pore networks that contribute to thermo-acoustic performance and have been combined with kapok in sustainable concrete systems to improve insulation and pore structure.²⁸⁵ Luffa fibers offer an intrinsically porous structure suitable for insulation panels,²⁸¹ while agricultural residues such as corn husk fibers and wood fibers exploit cellular morphologies for sound absorption and thermal regulation.^286,287 Hemp and other cellulose fibers, typically classified for reinforcement, also fall within this insulation category when used in porous assemblies due to their internal pore structure and renewable origin. Marine fibers from Posidonia oceanica further extend this group, with loose-fill bulk densities ranging from 17 to 155 kg m⁻³, indicating suitability for lightweight thermal insulation.²⁸⁸

Animal fibers form a parallel insulation class based on hierarchical microstructures rather than large lumens. Wool fibers generate stable air pockets through natural crimp and surface complexity, supporting thermal and acoustic insulation in standalone materials and in hybrid systems blended with agricultural residues such as sugarcane bagasse.²⁸¹ Feather fibers derived from poultry waste exhibit a branched architecture with hollow quills and barbules, producing lightweight, highly porous assemblies that effectively trap air while offering a sustainable route for waste valorization.²⁸⁹ Although not biologically derived, mineral fibers such as rock wool and porous mineral aggregates including pumice stone powder display analogous insulation behavior through fibrous skeletons and air-filled pore networks, justifying their inclusion as structural analogues within this insulation-based classification.²⁹⁰

4.2.3 Comfort-oriented and apparel-grade natural fibers. Natural fibers classified for comfort and apparel applications are distinguished by fineness, flexibility, moisture management, surface smoothness, and skin compatibility, all of which govern drape, handle, and thermo-physiological comfort.⁷⁶ Fiber fineness, commonly expressed as diameter in micrometers, plays a central role, as finer fibers generally yield softer and more flexible textiles. Silk exhibits the finest natural filament diameter, typically 10 to 13 µm, which accounts for its characteristic drape and luxurious hand feel. Merino wool, valued for next-to-skin comfort, usually has mean fiber diameters below 21.5 µm, whereas coarser wool fibers exceeding 25 µm tend to induce prickle.^76,291 Cotton occupies an intermediate range, typically 12 to 22 µm, providing a balance between softness and durability, while flax fibers are comparatively coarser at 12 to 50 µm and may feel stiff unless appropriately processed.²⁹²

Flexibility, closely related to bending rigidity and influenced by both fiber diameter and modulus, further differentiates apparel-grade fibers. Silk exhibits low bending resistance due to its β-pleated sheet molecular structure, resulting in smooth drape, while wool derives flexibility and resilience from its natural crimp and surface scales.⁷⁶ Cotton's twisted ribbon morphology contributes to its pliability, whereas flax, due to higher crystallinity and lignin content, is inherently stiffer but can be rendered suitable for apparel through treatments such as enzymatic retting and mercerization.²⁹³ Moisture management is another defining criterion, encompassing hygroscopicity, wicking, and evaporative efficiency. Wool demonstrates exceptional dynamic moisture regulation by absorbing up to 30% of its weight in moisture vapor without feeling wet, maintaining thermal comfort even in damp conditions. Cotton shows high hygroscopicity with around 8% moisture regain and effective capillary wicking, while bamboo fibers, often used in blends, enhance spreading and wetted area in fabrics.²⁹⁴ Silk, though less effective in liquid wicking, allows efficient moisture vapor transmission. The hydrophilic nature of many plant fibers supports comfort in apparel but can require chemical modification when interfacing with hydrophobic polymer systems.²⁹⁵

Softness and skin compatibility further refine this classification. Silk exhibits very low surface friction, with coefficients around 0.15, producing a smooth and cool touch, while ultrafine merino wool minimizes prickle through reduced fiber diameter and bending stiffness.²⁹⁶ Cotton is widely regarded as skin-friendly due to its smooth cuticle and low irritation potential, whereas regenerated cellulose fibers such as lyocell and viscose offer enhanced softness through uniform fiber morphology.²⁹⁷ This comfort-oriented classification differs from botanical or structural groupings of fibers. Although fibers may be broadly categorized as plant-based, animal-based, or mineral-based, such classifications do not directly reflect tactile or physiological comfort. For example, cotton and lyocell are both cellulose-based but differ markedly in fibril orientation and surface morphology, leading to distinct comfort behavior, while lignocellulosic fibers such as bamboo, kenaf, and sugar palm exhibit varied microstructures that influence their textile performance.²⁹⁶ Consequently, this category groups fibers according to comfort-related functional attributes rather than origin or load-bearing capability.

4.2.4 Functional and protective natural fibers. Protective and high-temperature-resistant natural fibers are characterized by their ability to maintain functional performance under thermal loading, flame exposure, and chemically aggressive environments. Among these materials, mineral fibers, particularly basalt fiber, exhibit the highest level of inherent thermal and chemical stability due to their inorganic silicate composition.^269,298 Basalt fibers show low thermal conductivity, remain thermally stable up to approximately 800 °C, and possess melting temperatures exceeding 1000 °C, while being non-flammable and resistant to acids, alkalis, and ultraviolet radiation.^269,298 These characteristics explain their extensive use in cementitious composites, structural elements subjected to thermal cycling, and braking systems where frictional stability and durability at elevated temperatures are required.²⁹⁹ In addition to intrinsic properties, surface modification techniques such as magnetron sputtering with aluminum or zirconium dioxide coatings have been reported to further improve resistance to radiant and contact heat, while preserving the fundamental thermal and chemical stability of the basalt fiber itself.³⁰⁰

In contrast to mineral fibers, animal-derived fibers achieve thermal protection through different physicochemical mechanisms. Keratin-based fibers such as wool exhibit inherent flame resistance associated with their nitrogen- and sulfur-rich protein structure, which promotes the formation of a stable char layer during thermal exposure and suppresses flame propagation.⁴⁶ This behavior supports their use in protective textile systems where fire safety and moderate thermal resistance are required. However, the temperature tolerance and long-term thermal durability of keratin fibers remain lower than those of basalt fibers, which limits their suitability to applications involving less severe thermal conditions.

Plant-derived fibers further extend this progression, as their intrinsic thermal stability is generally lower, but their performance can be significantly modified through chemical treatments. Cotton, for example, exhibits a limiting oxygen index of approximately 18 percent and ignites readily in its untreated state.³⁰¹ To address this limitation, flame-retardant behavior has been introduced through chemical grafting, chelation, and coatings based on phosphorus-containing compounds, lignin, and hybrid nanoparticle systems, which impart durable flame retardancy along with auxiliary functions such as ultraviolet shielding and water repellence.²¹² Comparable strategies have been applied to other lignocellulosic fibers such as ramie and lyocell using phosphorus-based systems and bio-derived layer-by-layer assemblies to enhance flame-retardant and antibacterial properties.³⁰² Together with surface treatments such as mercerization and alternative approaches including microwave processing, these modifications improve thermal stability, durability, and compatibility with polymer matrices, enabling plant fibers to satisfy fire-safety requirements in composite systems alongside mineral and animal fibers.³⁰³

4.2.5 Sorption, filtration, and separation-oriented natural fibers. Natural fibers used for sorption of nonpolar liquids are distinguished by large hollow lumens, typically greater than 10 µm, hydrophobic surface chemistry, and low intrinsic wall porosity, which together enable efficient oil uptake through capillary entrapment and surface adsorption with minimal flow resistance.³⁰⁴ Kapok fiber (Ceiba pentandra) is a representative material in this group, as its pronounced hollow tubular structure and waxy cutin layer impart high hydrophobicity and oleophilicity, supporting effective oil spill remediation and oil–water separation.³⁰⁴ Sorption capacity depends on packing density and surface chemistry, with untreated kapok fibers reported to achieve oil sorption up to 20.72 g g⁻¹.³⁰⁵ Surface modifications such as calcium stearate or ZnO coatings further enhance sorption efficiency and reusability by altering surface roughness and chemical affinity.^4,9 Other naturally hollow fibers, including desert rose seed fibers, exhibit similar sorption behavior due to comparable morphology.³⁰⁶

Filtration-oriented fibers rely on different structural features, including small or collapsed lumens, generally below 2 µm, high surface hydrophilicity, and abundant surface-wall microporosity, which facilitate selective retention of particles or molecules.³⁰⁷ Filtration performance is governed by pore size distribution and internal surface area, often characterized by nominal or absolute pore ratings and quantified using BET analysis. Cellulose-based membranes illustrate this behavior by acting as selective barriers based on size exclusion, charge, and polarity, although membrane fouling remains a key limitation.³⁰⁸ In this context, modified kapok fibers coated with polyaniline demonstrate that surface chemistry manipulation can shift inherently sorptive fibers toward selective filtration functions, while carbon aerogels derived from kapok and regenerated cellulose provide controlled porosity suitable for oil–water filtration.³⁰⁹

Separation-oriented fibers extend these principles by combining controlled pore hierarchy with tunable surface chemistry to enable affinity-driven partitioning and selective permeation. Functionalized nanofibers bearing specific diammonium reagents have been used for selective recovery of iridium from rhodium, highlighting the role of tailored surface chemistry in separation processes.³¹⁰ Surface chemistry also governs fouling resistance and separation efficiency in membranes, as shown by zwitterionic surface layers in nanofiltration systems.³¹¹ Agricultural residues exhibit a spectrum of these behaviors depending on processing, with lignin-rich raw fibers favoring sorption, while alkali-oxidized fibers expose mesopores and surface charges that support filtration and separation.³¹² Examples such as plantain pseudostem and sugarcane fibers functionalized with TiO₂, graphene oxide, or stearic acid demonstrate enhanced crude oil absorption and oil–water separation through combined morphological and chemical modification, while variations in fiber cross-section and intrinsic composition further influence performance across sorption, filtration, and separation functions.³¹²

5 Extraction and processing of natural fibers

Extraction of natural fibers involves separating fibrous materials from plant tissues using biological or mechanical methods. The most common techniques include dew retting, water retting, and mechanical extraction, each offering specific benefits and limitations depending on conditions and fiber type. A brief comparison of these methods is presented in Table 6.

Table 6 Extraction techniques for natural fiber extraction

Extraction technique	Description	Duration	Benefits	Drawbacks	Ref.
Dew retting	Cellulose-rich plant materials are uniformly spread on grassy fields to undergo the combined influence of microorganisms, sunlight, air, and dew, which facilitate fiber separation	Typically takes 2–4 weeks, depending on local environmental conditions	Suitable for regions experiencing heavy dew, warm daytime temperatures, and limited water resources	Results in darker-colored fibers of slightly lower quality; agricultural land remains occupied for several weeks, and fibers are often contaminated with soil or fungal growth	313–316
Water retting	Plant stalks or parts rich in cellulose are submerged in natural water sources such as ponds, rivers, or tanks, allowing microbial action to aid in retting under regular supervision	Usually completed in 1–2 weeks, depending on the water's purity and temperature	Cost-effective, environmentally friendly, and simple to manage; produces uniform and high-quality fibers	Requires substantial amounts of clean water and skilled labor; inadequate monitoring can lead to inferior fiber quality	8 and 317–319
Mechanical extraction	Fibers are separated mechanically using equipment such as hammer mills or decorticators that crush plant tissues and break down adhesive substances binding the fibers	Duration varies based on the fiber yield and production scale	Enables the rapid extraction of large quantities of short fibers suitable for industrial use	Involves high operational costs, increased energy consumption, and potential environmental impacts compared with other methods	56 and 320

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5.1 Chemical extraction method

Chemical extraction is one of the most widely used approaches for separating fibers from plant stems and leaves, particularly when rapid and efficient removal of non-cellulosic materials is desired. Chemical maceration, also referred to as surfactant retting, involves the use of a heated chemical solution to degrade pectin and other binding substances that hold fibers together within plant tissues.³²¹ The process facilitates the detachment of the fibrous bundles from woody or cortical material, yielding cleaner and more uniform fibers. The retting solution typically contains chemical agents such as potassium hydroxide (KOH), sulfuric acid (H₂SO₄), calcium hypochlorite (Ca(ClO)₂), sodium carbonate (Na₂CO₃), or sodium hydroxide (NaOH).³²² These chemicals promote hydrolysis of pectic and hemicellulosic substances and, when combined with surface-active agents, help emulsify and remove non-cellulosic components such as lignin, waxes, and pectins through micelle and emulsion-forming mechanisms.³²³

Prior to chemical retting, harvested plant materials may be milled, crushed, or mechanically decorticated to increase the surface area and improve chemical penetration during processing. The treatment conditions, such as temperature, chemical concentration, and duration, are critical in determining fiber quality. Depending on these parameters, retting may last from a few minutes up to 48 hours.²³ Following chemical retting, the fibers are thoroughly washed with running water, then dried and combed to remove residual chemicals and impurities. This process typically produces high-purity fibers with smooth surfaces, uniform texture, and excellent adhesion properties for subsequent spinning, finishing, or composite reinforcement.³²¹ However, the disadvantages of this method include high operational costs, potential fiber damage under excessive chemical exposure, and water pollution resulting from effluent disposal, which have prompted ongoing research into more sustainable alternatives.

Recent advances have focused on optimizing chemical retting to reduce environmental impact and improve fiber quality. Nassar et al.³²⁴ developed a novel multi-step chemical extraction technique consisting of dewaxing, acetylation, and mercerization, with controlled reaction times and optional microwave-assisted heating. This sequential process effectively removes waxes and amorphous hemicellulose, increases fiber crystallinity, and enhances tensile strength, producing cellulose-rich fibers suitable for advanced bio-composite applications. Similarly, Balasubramanian et al.³²⁵ introduced a modified low-concentration alkali treatment for jute fibers using only 2% NaOH, followed by ethanol–acetic acid neutralization. This approach significantly reduces lignin and hemicellulose content while maintaining fiber integrity, resulting in cleaner surfaces and improved interfacial bonding with reduced chemical usage. The method offers an eco-friendlier and cost-effective alternative to traditional high-alkali treatments, supporting sustainable practices in natural fiber processing.

5.2 Biological methods

5.2.1 Water retting. Water retting is one of the oldest and most widely used biological extraction methods for separating fibers from plant stalks, particularly bast fibers such as flax, jute, kenaf, hemp, and ramie. In this process, the fiber-bearing plants are submerged in water for a period of 3 to 35 days, during which naturally occurring microorganisms decompose the pectin and hemicellulose that bind the fibers to the woody core and epidermis.³²⁶ Retting can be performed in running water bodies such as rivers and streams, or in static tanks or ponds, where the water is replaced every few days to maintain bacterial activity and prevent stagnation. The duration of retting depends largely on water temperature and microbial activity, with higher temperatures (around 28–40 °C) accelerating the process and enabling fiber separation within 3–5 days.³²³

The process primarily involves anaerobic bacterial action, where microorganisms such as Clostridium species digest the gummy substances holding the fibers together, allowing them to be easily extracted after drying and combing. Water-retted fibers are known for their superior fineness, color, luster, and strength compared to those obtained through mechanical or chemical methods. However, traditional water retting has several drawbacks, including high water consumption, the need for large soaking areas, and environmental pollution caused by the release of organic waste and fermentation gases.³²⁷ Furthermore, the method requires specialized drying and handling equipment, making it labor-intensive and costly. Due to these environmental and economic challenges, industrial-scale water retting has been banned or restricted in many regions, including much of Europe.³²²

Recent innovations aim to make water retting more sustainable and resource-efficient. A modern technique known as micro-pond retting reduces water usage by up to one-sixth of the traditional process through the use of microbial inoculation and water recycling systems.³²⁸ This method integrates aquaculture and crop production, utilizing retting residues as nutrient sources while minimizing environmental discharge. Hossain et al.³²⁹ demonstrated that alternative water sources such as tap, pond, and canal water could be effectively used for retting kenaf fibers, producing high-quality fibers with varying cellulose and lignin contents. Their findings suggest that fiber quality can be maintained without relying on large freshwater volumes, offering a more adaptable and sustainable approach to retting. Similarly, Harsányi et al.³³⁰ developed a controlled anaerobic water retting (AWR) process for flax fiber extraction. This system operates in closed bioreactors under strictly anaerobic conditions, eliminating the need for added chemicals or enzymes. The AWR process not only yields high-purity cellulose-rich fibers but also produces valuable by-products such as organic acids (notably acetic and butyric acid), hydrogen-rich gas, and biomethane.

5.2.2 Dew retting. Dew retting is considered the oldest and simplest biological method for separating fibers from plant stems, and it remains one of the most widely used retting techniques globally.³²² In this process, fiber-yielding crops such as flax, hemp, and jute are harvested and spread evenly on open fields, where natural moisture, temperature, and microbial activity facilitate fiber separation. The process typically takes 3 to 6 weeks, depending on environmental conditions such as humidity, rainfall, and air temperature. These factors influence the growth and metabolic activity of microorganisms, primarily fungi and bacteria, which gradually degrade the pectin and hemicellulose that bind fibers to the plant cortex and woody tissues.³²³

During dew retting, the crops are exposed to alternating wet and dry conditions, promoting the activity of aerobic microorganisms such as Clostridium, Bacillus, Pseudomonas, and Aspergillus species. These microbes produce pectinolytic and hemicellulolytic enzymes that break down non-cellulosic components, allowing the fibers to be separated more easily from the xylem. However, the success of dew retting depends heavily on environmental control and careful monitoring. Improper timing can result in over-retting, where excessive microbial action leads to partial degradation of cellulose and loss of fiber strength, or under-retting, where incomplete degradation leaves fibers difficult to extract and process.³³¹ Therefore, continuous observation of weather conditions, periodic turning of plants for uniform exposure, and optimization of retting duration are crucial to ensure homogenous retting and maintain fiber quality.

Despite its simplicity and low cost, dew retting has inherent limitations. Its dependence on weather conditions makes it unpredictable and unsuitable for regions with inconsistent temperature or humidity levels. Moreover, fibers obtained through dew retting are often darker in color and exhibit lower fineness and strength compared to those produced by water or chemical retting, primarily due to prolonged contact with soil and partial degradation of the fiber surface.³²⁷ Nevertheless, the method remains popular among small-scale and sustainable fiber producers because it requires minimal energy, water, and chemical input, aligning with eco-friendly agricultural practices.

Recent advancements aim to improve control and efficiency in dew retting by integrating microbial monitoring and biotechnology tools. Orm et al.³³² introduced a microbial enzyme-linked monitoring framework for hemp dew retting, employing high-throughput sequencing to correlate microbial taxa and enzymatic profiles with retting stages. This study identified Pseudomonas, Sphingomonas, and Cladosporium as key microbial indicators of retting progress, enabling better prediction and regulation of retting outcomes. Such biotechnological approaches enhance understanding of microbial succession and enzymatic activity in field retting environments, paving the way for more consistent fiber quality and shorter processing times.

5.2.3 Enzymatic retting. Enzymatic retting is a biotechnologically advanced fiber extraction method that utilizes specific enzymes to degrade the pectin and hemicellulose binding the fibers to plant tissues, thereby facilitating their separation. Unlike traditional retting methods that rely on uncontrolled microbial activity or harsh chemicals, enzymatic retting offers greater precision, uniformity, and fiber quality. The process begins soon after harvesting, when plants are lightly crushed or crimped using mechanical rollers to break the outer epidermis and increase enzyme penetration into the bast tissue.³³³ The prepared plant material is then incubated in a controlled tank environment containing a pectinolytic enzyme solution, often supplemented with xylanase or mannanase enzymes, at an optimized temperature and pH that support maximum enzymatic activity.³³⁴ The retting duration typically ranges between 2 and 24 hours, depending on the enzyme concentration, plant type, and temperature conditions.

The enzymes used in this process, such as pectinase, polygalacturonase, xylanase, and mannanase, specifically target pectin and hemicellulose, degrading the non-cellulosic cementing materials while preserving the cellulose microfibrils that impart strength to the fibers. As a result, enzymatic retting yields high-quality fibers characterized by smooth surfaces, high crystallinity, and superior mechanical performance. Additionally, the controlled enzymatic action minimizes fiber damage and color alteration compared to chemical or water retting methods. However, the main drawbacks of enzymatic retting are its high operational cost, attributed to enzyme production and purification, and the need for wastewater treatment and specialized equipment, which limit its industrial scalability.³³⁵

Recent studies have explored microbial consortia and enzyme-based bioaugmentation systems to make enzymatic retting more efficient and cost-effective. Ventorino et al.³³⁶ developed a microbial consortia-based retting approach for hemp fibers, employing selected strains of Bacillus, Paenibacillus, and Pseudomonas that exhibit synergistic enzymatic activity. The consortium displayed high pectinolytic activity while maintaining cellulose integrity, achieving effective fiber separation within five days and producing fibers with improved fineness and tensile properties. Similarly, Huang et al.³³⁷ introduced a fungal consortium-based bioaugmentation retting system for sisal fibers, consisting of Aspergillus micronesiensis, Penicillium citrinum, and Cladosporium species. This combination generated high levels of pectinase, xylanase, and mannanase, enhancing degumming efficiency and cellulose purity without causing cellulase-induced fiber degradation. The approach not only improved retting speed but also produced fibers with enhanced cleanliness, whiteness, and bonding characteristics suitable for textile and composite applications.

5.3 Hybrid extraction methods

5.3.1 Microwave-assisted retting. Microwave-assisted retting is a modern and energy-efficient technique developed to accelerate the separation of fibers from lignocellulosic plant materials through the use of microwave radiation. Unlike conventional retting methods that rely on slow microbial or chemical degradation, this approach utilizes dielectric heating, in which polar molecules—primarily water—absorb microwave energy and convert it into heat via molecular vibration and friction. The rapid and uniform heating generated by microwaves causes disruption of the middle lamella, which weakens the pectic and hemicellulosic bonds binding the fiber bundles to surrounding tissues.³³⁸ This process enables quick loosening of fiber bundles from the plant matrix, dramatically reducing retting time compared to traditional methods such as dew or water retting.

The primary advantage of microwave-assisted retting lies in its ability to provide precise control over process parameters, including temperature, exposure time, and moisture content. Controlled microwave energy ensures uniform heating throughout the plant material, resulting in consistent fiber quality and color while minimizing fiber damage. The process also significantly reduces microbial contamination, water consumption, and chemical usage, making it a cleaner and more sustainable alternative to conventional retting methods.³³⁹ Furthermore, microwave treatment can be integrated with mild chemical or enzymatic pretreatments, enhancing the degradation of pectins and hemicelluloses while preserving cellulose integrity. The combination of microwaves with alkaline or enzymatic solutions has been shown to produce fibers with smoother surfaces, improved purity, and enhanced mechanical properties, suitable for high-performance textile and composite applications.

In addition to its environmental advantages, microwave-assisted retting effectively eliminates issues such as odor emission, effluent generation, and prolonged fermentation, which are common drawbacks of biological and water-based retting techniques. However, the technology also presents certain limitations. The initial capital investment for industrial-scale microwave equipment is relatively high, and the process requires careful optimization to avoid localized overheating, which can lead to thermal degradation of cellulose and reduced fiber strength.³⁴⁰ Factors such as plant moisture content, fiber density, and radiation power must be precisely controlled to achieve optimal results. Despite these challenges, microwave-assisted retting is emerging as a promising, eco-friendly, and time-efficient fiber extraction technology. Its potential to combine speed, sustainability, and product quality makes it a valuable innovation in the modernization of natural fiber processing, offering an advanced alternative to traditional retting practices for the textile industry.

5.3.2 Duralin process. The Duralin process, developed by Ceres B.V., is a thermo-chemical method designed to enhance the dimensional stability and environmental resistance of bast fibers such as flax and hemp.³⁴¹ The process consists of three main stages: hydrothermolysis, drying, and curing.³⁴² In the first stage, the plant stems are treated with steam in an autoclave at 160 °C for 30 minutes, which softens the lignocellulosic structure and partially breaks down lignin and hemicellulose. The stems are then oven-dried to remove moisture, followed by curing at 150 °C for 2 hours. During curing, the degraded lignin and hemicellulose components form low-molecular-weight aldehydes and phenolic compounds, which polymerize into a natural resin that binds the cellulose microfibrils together, improving water resistance and strength.³⁴³

After treatment, the fibers are extracted by crushing, decortication, or scutching, producing clean, high-quality bast fibers with enhanced physical and surface properties suitable for composite and technical textile applications.²⁰⁸ The Duralin process eliminates the need for conventional retting and yields strong, dimensionally stable, and hydrophobic fibers, making it a sustainable and efficient alternative for high-performance natural fiber production.³⁴¹

5.4 Emerging methods

Modern research in natural fiber processing has led to the development of several innovative extraction techniques that aim to improve efficiency, reduce environmental impact, and enhance fiber quality. Among these, steam explosion, ultrasound retting, and stand retting are notable for their effectiveness in fiber separation, shortened processing times, and potential for industrial scalability.

The steam explosion method (STEX) is a thermo-mechanical fiber extraction process that utilizes high-pressure steam, temperature, and rapid decompression to separate fibers from lignocellulosic plant materials.³²¹ In this technique, the dried plant stems are exposed to high-pressure saturated steam, which penetrates the plant tissues and softens the lignin and hemicellulose components. The process is followed by a sudden pressure release, generating intense thermomechanical shear forces that rupture the middle lamella, the binding layer between fibers, leading to efficient fiber separation.³²² The resulting fibers exhibit fine texture, smooth surfaces, and mechanical properties comparable to cotton, making this method highly suitable for textile-grade natural fibers. In addition to producing high-quality fibers, steam explosion requires less chemical input and water, thus offering an eco-friendlier and rapid alternative to traditional retting techniques.

Another innovative technique, ultrasound retting, combines acoustic cavitation and mild chemical treatment to accelerate fiber extraction. In this process, cleaned and crushed plant stems are submerged in a hot water bath (around 70 °C for 24 h) containing low concentrations of alkali and surfactants, and then exposed to high-intensity ultrasound (1 kW, 40 kHz).³⁴⁴ The ultrasonic vibrations generate microscopic cavitation bubbles that collapse near the fiber surfaces, producing localized shock waves and micro-jets that break down the pectin-rich matrix binding the fibers. This results in faster separation, smoother fiber surfaces, and improved uniformity compared to conventional water retting. While the method significantly reduces retting time and enhances fiber fineness, cleanliness, and mechanical strength, large-scale industrial implementation remains limited due to high equipment cost and energy requirements.³⁴⁵ Nevertheless, ultrasound-assisted retting represents a promising green technology for next-generation fiber extraction.

The stand retting method is a modified version of dew retting, developed to address some of its limitations. In one variation, the fiber crops are treated in the field before harvest with glyphosate (N-phosphonomethyl glycine), a desiccant that facilitates fiber separation by weakening the plant tissues.³²² This approach yields fibers with improved mechanical properties compared to traditional dew retting.³⁴⁶ Another variation involves thermal treatment, where the lower sections of standing plants are heated to about 100 °C and subsequently dried for several days.³²³ This method reduces dependency on weather conditions and accelerates retting. Although stand retting minimizes risks of fiber damage from rain or prolonged field exposure, it incurs higher operational costs due to the need for controlled heating systems.³⁴⁷ Moreover, the use of glyphosate-based chemicals raises environmental and health concerns, including soil toxicity and adverse effects on microbial and aquatic ecosystems,³⁴⁸ making its use undesirable in sustainable fiber production.

6 Modification of natural fibers

6.1 Alkaline treatment

The alkaline treatment (also known as alkali or mercerization treatment) is one of the simplest, most economical, and effective methods for improving the adhesion and interfacial bonding between natural fibers and polymer matrices.³⁴⁹ In this process, the fibers are treated with an aqueous sodium hydroxide (NaOH) solution, which modifies the cellulosic molecular structure and enhances mechanical interlocking with the matrix. The treatment increases fiber fragmentation and disaggregation, altering the orientation of crystalline cellulose and creating amorphous regions where water molecules penetrate and separate cellulose microfibrils.³⁵⁰ The alkali reacts with hydroxyl (–OH) groups in cellulose, forming fiber-O–Na bonds and reducing the number of hydrophilic groups, thereby increasing moisture resistance.³⁵¹ This process also removes hemicellulose, lignin, pectin, wax, and oil, resulting in a cleaner and more uniform surface, which improves stress transfer between fiber and matrix.³⁵² The treatment decreases fiber diameter, increases the effective surface area and aspect ratio, and improves adhesion strength, provided that the alkali concentration is optimized; excessively high concentrations can cause over-delignification and fiber damage. Brígida et al.³⁵³ found that alkaline treatment is the most efficient technique for exposing cellulose in natural fsibers and that it enhances the thermal stability of green coconut fibers while maintaining their hydrophilic character. Fig. 14 shows SEM micrographs of longitudinal views of untreated and 6% alkaline-treated kenaf fibers, where surface impurities are visibly removed, and smoother, cleaner fiber surfaces are observed.

Fig. 14 SEM micrographs of (a) untreated hemp fibre and (b) 6% NaOH treated hemp fibre. This figure has been reproduced from ref. 354 with permission from Elsevier, copyright 2003.

6.2 Silane treatment

The silane treatment method is a widely used chemical surface modification technique designed to improve the adhesion between natural fibers and polymer matrices by forming stable covalent bonds at the interface. In this approach, silane coupling agents are applied to the fiber surface, where they coat the micro-pores and irregularities, creating a molecular bridge between the hydrophilic fiber and the hydrophobic matrix.³⁵⁵ During the initial stage, silanols are generated through the hydrolysis of the alkoxy groups in the silane compound in the presence of moisture. These silanols then react with the hydroxyl (–OH) groups of cellulose on the fiber surface, forming Si–O-cellulose bonds, while the other reactive end of the silane molecule condenses with the functional groups of the matrix, producing a siloxane (Si–O–Si) bridge.³⁵⁶ This condensation reaction establishes molecular continuity across the interface, resulting in improved chemical compatibility and load transfer between the two phases. The hydrophobic hydrocarbon chains of silane further reduce fiber swelling and moisture absorption, enhancing the dimensional stability of the composite.³⁵² Fibers treated with silane show superior tensile strength and interfacial adhesion compared to those modified only by alkali treatment.³⁵⁷

6.3 Acetylation treatment

The acetylation treatment is a chemical modification process that enhances the dimensional stability, moisture resistance, and interfacial adhesion of natural fibers by introducing acetyl groups (–COCH₃) into their cellular structure.³⁵⁸ In this method, the fibers are first soaked in acetic acid and then treated with acetic anhydride in the presence of an acid catalyst for 1–3 hours at elevated temperatures, as acetic acid and acetic anhydride alone cannot react effectively with the fiber surface.¹³ During treatment, an esterification reaction occurs between the hydroxyl (–OH) groups of the cellulose and the carboxylic or anhydride groups, resulting in the formation of ester linkages within the fiber structure.³⁵⁹ This substitution of hydroxyl groups by acetyl groups reduces the number of hydrophilic sites, thereby lowering the fiber's ability to absorb moisture and swell.

The acetylation process also removes surface waxes and cuticular layers, producing a smoother and more uniform fiber surface with improved compatibility with hydrophobic polymer matrices. According to Tserki et al.,³⁶⁰ acetylation of flax and hemp fibers significantly decreases moisture absorption, eliminates non-crystalline constituents, and improves stress transfer efficiency due to better interfacial bonding. Zafeiropoulos et al.³⁶¹ further reported that acetylation alters both the bulk and surface properties of flax fibers, leading to enhanced dimensional stability and mechanical behavior in composite materials. Fig. 15 presents SEM micrographs of surface views of untreated and 18% acetylation-treated flax fibers, where the treated fibers exhibit a cleaner and smoother morphology compared to untreated samples.

Fig. 15 SEM micrographs showing the surface morphology of (a) untreated and (b) 18% acetylation-treated flax fibers. This figure has been reproduced from ref. 362 with permission from BME-PT, copyright 2021.

6.4 Peroxide treatment

The peroxide treatment is a chemical surface modification technique that enhances the adhesion, thermal stability, and moisture resistance of natural fibers by introducing reactive radicals onto their surfaces. In this method, peroxide-induced grafting, typically involving compounds such as hydrogen peroxide or organic peroxides, is used to anchor polyethylene or other coupling agents onto the fiber surface.³⁶³ When activated, the peroxide molecules decompose to form free radicals, which react with the hydroxyl (–OH) groups present in the cellulose structure of the fibers and with the functional groups of the polymer matrix. This reaction promotes strong covalent bonding at the fiber–matrix interface, resulting in improved stress transfer and better compatibility between the hydrophilic natural fiber and the hydrophobic polymer matrix.¹³¹

Peroxide treatment also leads to the reduction of hydroxyl groups, thereby decreasing the moisture absorption capacity of the fibers and enhancing their dimensional and thermal stability.³⁶⁴ The resulting fibers exhibit smoother surfaces and reduced porosity, which contribute to improved mechanical performance in composite applications. Fig. 16 shows SEM micrographs of surface views of untreated and peroxide-treated flax fibers, clearly illustrating the removal of surface impurities and the formation of a cleaner, more uniform surface morphology after treatment.

Fig. 16 SEM images depicting surface modifications of flax fibers: (a) untreated and (b) after peroxide treatment. This figure has been reproduced from ref. 365 with permission from SAGE Publications, copyright 2026.

6.5 Corona treatment

Corona treatment is a physical surface modification method that increases the surface energy of natural fibers through oxidation, improving compatibility between hydrophilic fibers and hydrophobic matrices.³⁶⁶ The process involves two aluminum electrodes separated by a quartz dielectric spacer, where electrical discharge passes through an air gap to treat the fiber surface.³⁶⁷ Since fibers are placed on the electrode surface, mainly one side is exposed, though in composites, the entire lateral surface contributes to reinforcement.³⁶⁸ SEM images, as presented in Fig. 17, show that longer treatment times produce rougher fiber surfaces, enhancing mechanical interlocking between fiber and matrix. The treatment activates surface sites along polymer chains, allowing oxidation and etching, leading to up to 30% improvement in Young's modulus and tensile strength of hemp and Miscanthus–polypropylene composites, while composites with polylactic acid show around 20% improvement.³⁶⁹ Although corona treatment modifies fiber surfaces effectively, potential fiber damage and the long-term stability of the interfacial bonding require further investigation.

Fig. 17 SEM images of corona-treated hemp fiber (a) untreated, (b) after 15 min, (c) after 30 min, (d) after 40 min. This figure has been reproduced from ref. 368 with permission from Elsevier B.V., copyright 2009.

7 Environmental impact and sustainability analysis

Energy consumption during natural fiber processing and modification is a key contributor to environmental impact and depends strongly on treatment type, duration, and effluent generation. To evaluate energy demand per unit of treated fiber, the fiber source and energy source were kept constant. A 1 hour oven drying process at 120 °C was assumed to consume 1.1 kW, while 1 hour of laboratory mixing using a standard mixer required 216 W.³⁷⁰ Chemical treatments such as silane and acetylation generally involve pre-treatment steps, with chemical concentrations ranging from 1% to 5%. Alkaline and acetylation treatments typically require about 2 hours, whereas silane treatment extends up to 12 hours due to slow hydrolysis and condensation reactions governing silane coupling to fiber surfaces. Maleated treatment occurs during composite manufacturing and therefore does not require separate processing time or effluent handling. As shown in Fig. 18, total energy consumption includes both process energy from mixing, washing, and drying and energy associated with effluent management, which increases with effluent volume.³⁷⁰ Alkaline treatment, involving 2 hours of processing and 6 hours of drying at 120 °C, consumed approximately 10 kW, while acetylation treatment required about 17.5 kW due to multiple processing and drying steps. Silane treatment exhibited higher energy demand because of prolonged mixing at 60 °C, and this increased further when pre-treatment was applied. When comparing pre-treated acetylation and silane treatments, acetylation showed higher effluent-related energy consumption, whereas silane treatment required higher process energy due to extended treatment duration.³⁷⁰

Fig. 18 Energy consumption for different chemical treatments per unit of natural fiber.

The higher energy demand associated with chemical modification routes is directly linked to the underlying reaction mechanisms responsible for surface functionalization and by-product formation:

Alkaline treatment (mercerization):

Cell–OH + NaOH → Cell–O⁻ Na⁺ + H₂O

Acetylation:

Cell–OH + (CH₃CO)₂O → Cell–OCOCH₃ + CH₃COOH

Silane treatment (hydrolysis and condensation):

R–Si(OR′)₃ + 3H₂O → R–Si(OH)₃ + 3R′OH Cell–OH + R–Si(OH)₃ → Cell–O–Si–R + H₂O

These reactions explain the increased energy demand observed in Fig. 18, as alkaline and acetylation treatments generate significant aqueous effluents requiring repeated washing and drying, while silane treatments demand prolonged thermal activation to complete hydrolysis and condensation at the fiber surface. Maleated coupling, in contrast, proceeds through in situ radical grafting during melt processing and therefore avoids additional solvent use and post-treatment drying, resulting in lower net energy input per unit fiber.

Beyond processing energy, natural fiber production and utilization are closely linked to socio-economic sustainability, particularly in fiber-producing regions where these materials support livelihoods and local industries. Natural fibers offer low production cost, wide availability, low density, favorable mechanical performance, thermal and acoustic insulation, and reduced health risks during processing, supporting their continued use in textile and composite applications.³⁷¹ In countries such as India, Bangladesh, and Kenya, cultivation and processing of cotton, jute, hemp, sisal, and related fibers provide employment for millions of rural workers and contribute significantly to export-oriented economies.³⁷² In Indonesia, initiatives such as the Ramie Consortium (KORI) and the Natural Fiber Council (DSI) promote integrated systems covering cultivation, fiber extraction, spinning, and weaving of fibers including abaca, kenaf, bamboo, pineapple, sisal, cotton, and ramie, reducing dependence on imported cotton and strengthening domestic production chains.³⁷³ These efforts are complemented by the increasing utilization of agricultural residues such as pineapple leaves, banana stems, rice straw, and palm waste as alternative fiber sources within circular production approaches.³⁷⁴ Community-based extraction units and small-scale enterprises across Southeast Asia employ traditional retting and decortication methods to produce fibers for handicrafts, apparel, and home textiles, providing additional income for farmers despite low yields, such as 2.5 kg of pineapple fiber from 100 kg of fresh leaves.³⁷⁵

At the industrial level, these socio-economic benefits intersect with environmental considerations as natural fibers are increasingly incorporated into bio-based textiles and fiber–reinforced composites for automotive interiors, furnishings, and protective applications, offering lightweight and cost-effective alternatives to synthetic fibers.³⁷⁶ Government incentives and national research programs further support these developments by encouraging collaboration between academia, industry, and farming communities and promoting eco-packaging and biotextiles derived from agricultural residues.³⁷⁷ The adoption of circular economy practices, including reuse, recycling, and upcycling of fiber waste, improves resource efficiency and supports local employment while reducing material losses across the value chain.³⁷⁸

Despite these advantages, the textile and fashion industries continue to exert substantial environmental pressure due to intensive resource use, energy consumption, and waste generation. The production of natural fibers such as wool, cotton, and leather contributes to water pollution, land degradation, and greenhouse gas emissions, particularly methane, which has a significantly higher global warming potential than carbon dioxide.³⁷⁹ Methane emissions largely originate from livestock associated with wool production, and their reduction provides a rapid pathway for climate mitigation due to methane's short atmospheric lifetime. Strategies such as increasing the use of recycled wool, transitioning from animal-based to next-generation leather, adopting renewable electricity, electrifying processing stages, and using low-carbon transport fuels can substantially reduce emissions. A complete shift from virgin to recycled wool combined with an 80% transition from animal-based to next-generation leather could nearly achieve a 30% methane reduction target by 2030.³⁸⁰ Organizations such as Collective Fashion Justice support brands in quantifying methane footprints and identifying reduction pathways.

8 Challenges and opportunities

Although natural fibers are widely recognized for their biodegradability, renewability, and lower environmental footprint compared to synthetic alternatives,³⁸¹ several challenges still hinder their large-scale adoption in the fashion industry. One of the key challenges lies in their dependency on agricultural and climatic conditions, which can cause fluctuations in fiber quality and yield. The cultivation of certain natural fibers, such as cotton, demands significant water and land resources and often involves the use of pesticides and fertilizers that contribute to soil degradation and water pollution.³⁸² Similarly, animal-based fibers like wool, leather, and silk, though renewable, can generate high carbon emissions and raise ethical concerns regarding animal welfare.³⁸³ Furthermore, natural fibers may lack some of the functional advantages of synthetics, such as elasticity, moisture resistance, and extended durability, making them less suitable for performance wear.³⁸⁴ Processing methods for natural fibers also tend to be less efficient, and their mechanical properties can vary depending on factors such as fiber type, growth conditions, and extraction techniques.³⁸⁵

Despite these challenges, natural fibers offer substantial opportunities for advancing sustainability and innovation in the textile and fashion sectors. Their biodegradability and renewability make them ideal for developing circular and eco-friendly production models that minimize environmental pollution.³⁸⁶ The use of locally sourced raw materials such as hemp, flax, jute, and kenaf not only reduces transportation-related emissions but also supports regional economies and promotes soil regeneration through carbon sequestration and heavy metal absorption. Additionally, advancements in fiber processing technologies, such as enzymatic treatments, blending with elastomers, and eco-friendly coatings, are improving the mechanical and comfort properties of natural fibers, allowing them to compete more effectively with synthetic materials.³⁸⁷ As sustainability becomes a core strategic priority for modern businesses,³⁸⁸ the fashion industry has an opportunity to leverage natural fibers not only to reduce its ecological footprint but also to align with consumer demand for ethical, durable, and environmentally responsible products. With continued innovation, education, and policy support, natural fibers can play a pivotal role in transforming fashion into a more sustainable and resilient global industry.

9 Conclusion

This review demonstrates that natural fibers should not be viewed as a single sustainable solution but as a diverse group of materials whose performance and environmental relevance depend on source-specific structure, chemistry, and processing routes. Plant-based fibers such as cotton, jute, hemp, flax, bamboo, and kapok exhibit wide variation in cellulose crystallinity, lignin content, and lumen morphology, which governs their mechanical strength, moisture response, and thermal behavior. Animal-derived fibers, including wool, silk, feather fibers, and human hair, introduce protein-based chemistries where keratin and fibroin structures impart elasticity, insulation, and toughness but impose limitations related to thermal stability and processing energy. The comparative discussion with mineral fibers highlights how inorganic structures offer superior thermal resistance while raising critical health and sustainability constraints, reinforcing the need for application-driven fiber selection rather than generalized sustainability claims.

The analysis further shows that chemical modification is essential for improving compatibility and performance but represents a key trade-off between functional gains and environmental burden. Alkali, acetylation, silane, and maleated treatments operate through distinct chemical pathways that alter fiber surface chemistry and interfacial behavior, yet they differ substantially in energy demand, treatment duration, and effluent generation. The energy assessment presented indicates that prolonged treatments, particularly silane-based systems, contribute disproportionately to total environmental impact despite their effectiveness, underscoring the need to evaluate modification strategies beyond mechanical performance alone.

From a sustainability perspective, the environmental benefits of natural fibers are closely tied to regional availability, agricultural practices, and the use of residues rather than dedicated crops. The utilization of pineapple leaves, banana stems, rice straw, and palm waste offers clear advantages by reducing waste streams and supporting rural economies, but these benefits can be diminished by energy-intensive processing or inefficient effluent management. Animal-based fibers further illustrate the complexity of sustainability assessment, where durability and insulation performance must be balanced against emissions and land-use impacts.

Overall, this review integrates fiber structure, chemical modification, processing energy, and environmental impact into a unified framework, identifying moisture sensitivity, interfacial incompatibility, treatment-related energy costs, and supply variability as key constraints. Addressing these limitations through lower-energy chemical strategies, application-specific fiber selection, and improved processing efficiency is essential for translating the sustainability potential of natural fibers into scalable textile and composite applications.

Author contributions

Sayam Sayam: conceptualization, methodology, resources, software, supervision, validation, visualization, writing – original draft preparation, and writing – review & editing.

Conflicts of interest

No conflicts of interest.

Data availability

This review does not contain any original data. All the data were written in the manuscript.

Acknowledgements

This research received no external funding. The author, however, used Grammarly software to improve the grammatical accuracy of the manuscript.

References

1. F. M. AL-Oqla and S. M. Sapuan, Natural fiber reinforced polymer composites in industrial applications: feasibility of date palm fibers for sustainable automotive industry, J. Cleaner Prod., 2014, 66, 347–354,  DOI:10.1016/j.jclepro.2013.10.050.
2. M. R. Sanjay and S. Siengchin, Lightweight Natural Fiber Composites, J. Appl. Agric. Sci. Technol., 2019, 3, 178,  DOI:10.32530/jaast.v3i2.108.
3. M. Sanjay and B. Yogesha, Studies on Natural/Glass Fiber Reinforced Polymer Hybrid Composites: An Evolution, Mater. Today Proc., 2017, 4, 2739–2747,  DOI:10.1016/j.matpr.2017.02.151.
4. G. R. Arpitha, M. R. Sanjay, P. Senthamaraikannan, C. Barile and B. Yogesha, Hybridization Effect of Sisal/Glass/Epoxy/Filler Based Woven Fabric Reinforced Composites, Exp. Tech., 2017, 41, 577–584,  DOI:10.1007/s40799-017-0203-4.
5. P. Madhu, M. R. Sanjay, P. Senthamaraikannan, S. Pradeep, S. S. Saravanakumar and B. Yogesha, A review on synthesis and characterization of commercially available natural fibers: Part II, J. Nat. Fibers, 2019, 16, 25–36,  DOI:10.1080/15440478.2017.1379045.
6. K. Oksman, Y. Aitomäki, A. P. Mathew, G. Siqueira, Q. Zhou, S. Butylina, S. Tanpichai, X. Zhou and S. Hooshmand, Review of the recent developments in cellulose nanocomposite processing, Composites, Part A, 2016, 83, 2–18,  DOI:10.1016/j.compositesa.2015.10.041.
7. A. Kicińska-Jakubowska, E. Bogacz and M. Zimniewska, Review of Natural Fibers. Part I—Vegetable Fibers, J. Nat. Fibers, 2012, 9, 150–167,  DOI:10.1080/15440478.2012.703370.
8. P. Manimaran, P. Senthamaraikannan, M. R. Sanjay, M. K. Marichelvam and M. Jawaid, Study on characterization of Furcraea foetida new natural fiber as composite reinforcement for lightweight applications, Carbohydr. Polym., 2018, 181, 650–658,  DOI:10.1016/j.carbpol.2017.11.099.
9. M. R. Sanjay, P. Madhu, M. Jawaid, P. Senthamaraikannan, S. Senthil and S. Pradeep, Characterization and properties of natural fiber polymer composites: A comprehensive review, J. Cleaner Prod., 2018, 172, 566–581,  DOI:10.1016/j.jclepro.2017.10.101.
10. G. Bogoeva-Gaceva, M. Avella, M. Malinconico, A. Buzarovska, A. Grozdanov, G. Gentile and M. E. Errico, Natural fiber eco-composites, Polym. Compos., 2007, 28, 98–107,  DOI:10.1002/pc.20270.
11. M. Sain and S. Panthapulakkal, Bioprocess preparation of wheat straw fibers and their characterization, Ind. Crops Prod., 2006, 23, 1–8,  DOI:10.1016/j.indcrop.2005.01.006.
12. R. Sinclair, Understanding Textile Fibres and Their Properties, Text. Fash., 2015, 3–27,  DOI:10.1016/B978-1-84569-931-4.00001-5.
13. O. Faruk, A. K. Bledzki, H.-P. Fink and M. Sain, Biocomposites reinforced with natural fibers: 2000–2010, Prog. Polym. Sci., 2012, 37, 1552–1596,  DOI:10.1016/j.progpolymsci.2012.04.003.
14. L. Mohammed, M. N. M. Ansari, G. Pua, M. Jawaid and M. S. Islam, A Review on Natural Fiber Reinforced Polymer Composite and Its Applications, Int. J. Polym. Sci., 2015, 2015, 1–15,  DOI:10.1155/2015/243947.
15. V. Chauhan, T. Kärki and J. Varis, Review of natural fiber-reinforced engineering plastic composites, their applications in the transportation sector and processing techniques, J. Thermoplast. Compos. Mater., 2022, 35, 1169–1209,  DOI:10.1177/0892705719889095.
16. E. Aprianti, P. Shafigh, S. Bahri and J. N. Farahani, Supplementary cementitious materials origin from agricultural wastes – A review, Constr. Build. Mater., 2015, 74, 176–187,  DOI:10.1016/j.conbuildmat.2014.10.010.
17. R. Arjmandi, A. Hassan, K. Majeed and Z. Zakaria, Rice Husk Filled Polymer Composites, Int. J. Polym. Sci., 2015, 2015, 1–32,  DOI:10.1155/2015/501471.
18. K. N. Bharath and S. Basavarajappa, Applications of biocomposite materials based on natural fibers from renewable resources: a review, Sci. Eng. Compos. Mater., 2016, 23, 123–133,  DOI:10.1515/secm-2014-0088.
19. J. Holbery and D. Houston, Natural-fiber-reinforced polymer composites in automotive applications, JOM, 2006, 58, 80–86,  DOI:10.1007/s11837-006-0234-2.
20. A. Bledzki, Composites reinforced with cellulose based fibres, Prog. Polym. Sci., 1999, 24, 221–274,  DOI:10.1016/S0079-6700(98)00018-5.
21. Y. Li, Y.-W. Mai and L. Ye, Sisal fibre and its composites: a review of recent developments, Compos. Sci. Technol., 2000, 60, 2037–2055,  DOI:10.1016/S0266-3538(00)00101-9.
22. D. Verma and S. Sharma, Green Biocomposites: A Prospective Utilization in Automobile Industry, Green Biocompos., 2017, 167–191,  DOI:10.1007/978-3-319-49382-4_8.
23. N. Reddy and Y. Yang, Biofibers from agricultural byproducts for industrial applications, Trends Biotechnol., 2005, 23, 22–27,  DOI:10.1016/j.tibtech.2004.11.002.
24. M. Jawaid and H. P. S. Abdul Khalil, Cellulosic/synthetic fibre reinforced polymer hybrid composites: A review, Carbohydr. Polym., 2011, 86, 1–18,  DOI:10.1016/j.carbpol.2011.04.043.
25. N. Reddy and Y. Yang, Properties of High-Quality Long Natural Cellulose Fibers from Rice Straw, J. Agric. Food Chem., 2006, 54, 8077–8081,  DOI:10.1021/jf0617723.
26. S. Shinoj, R. Visvanathan, S. Panigrahi and M. Kochubabu, Oil palm fiber (OPF) and its composites: A review, Ind. Crops Prod., 2011, 33, 7–22,  DOI:10.1016/j.indcrop.2010.09.009.
27. M. Essaket, M. El Wazna, A. Boukhriss, I. Essaket, A. El Bouari, O. Cherkaoui and A. El Maliki, A comparative study and thermophysical characterization of wool fiber from different regions of Morocco, Biomass Convers. Biorefinery, 2024, 14, 17941–17953,  DOI:10.1007/s13399-023-03988-2.
28. A. Russel, The Potential for High-Value Animal Fibre Production, Outlook Agric., 1994, 23, 129–135,  DOI:10.1177/003072709402300209.
29. Z. Czaplicki, E. Gliścińska and W. Machnowski, Natural Silk – an Unusual Fibre: Origin, Processing and World Production, Fibres Text. East. Eur., 2021, 29, 22–28,  DOI:10.5604/01.3001.0014.9291.
30. V. Ş. Agatha Popescu and H. N. Ciocan, New Trends In The Global Silk Production In The Period 2011-2022, Sci. Papers, Ser. Manag. Econom. Eng. Agric. Rural Dev., 2024, 24, 1–12 . https://managementjournal.usamv.ro/pdf/vol.24_1/Art78.pdf.
31. W. Mahjoub, S. Ukhnaa, J.-Y. Drean and O. Harzallah, Influence of Genetic and Non-Genetic Factors on the Physical and Mechanical Properties of Mongolian Cashmere Fiber Properties, Fibers, 2024, 12, 84,  DOI:10.3390/fib12100084.
32. D. Marsili, B. Terracini, V. Santana, J. Ramos-Bonilla, R. Pasetto, A. Mazzeo, D. Loomis, P. Comba and E. Algranti, Prevention of Asbestos-Related Disease in Countries Currently Using Asbestos, Int. Res. J. Publ. Environ. Health, 2016, 13, 494,  DOI:10.3390/ijerph13050494.
33. T. Sango, A. M. Cheumani Yona, L. Duchatel, A. Marin, M. Kor Ndikontar, N. Joly and J.-M. Lefebvre, Step–wise multi–scale deconstruction of banana pseudo–stem (Musa acuminata) biomass and morpho–mechanical characterization of extracted long fibres for sustainable applications, Ind. Crops Prod., 2018, 122, 657–668,  DOI:10.1016/j.indcrop.2018.06.050.
34. S. M. Sapuan, A. Leenie, M. Harimi and Y. K. Beng, Mechanical properties of woven banana fibre reinforced epoxy composites, Mater. Des., 2006, 27, 689–693,  DOI:10.1016/j.matdes.2004.12.016.
35. B. R. Nebangka, S. Marselina and J. Pongoh, Potensi Pengembangan Pisang Abaka (Musa Textilis Nee) Di Pulau Karakelang, Ceylon Coconut Q., 2019, 11, 11,  DOI:10.35791/cocos.v1i1.27336.
36. M. Jawaid, P. M. Tahir and N. Saba, Lignocellulosic Fibre and Biomass-Based Composite Materials, Elsevier, 2017,  DOI:10.1016/C2015-0-04050-3.
37. P. Zakikhani, R. Zahari, M. T. H. Sultan and D. L. Majid, Extraction and preparation of bamboo fibre-reinforced composites, Mater. Des., 2014, 63, 820–828,  DOI:10.1016/j.matdes.2014.06.058.
38. E. A. W. Dransfield, Plant Resources of South-East Asia. No. 7: Bamboos, Backhuys Publishers, Leiden, 1995.
39. D. Murdiyanto, Potensi Serat Alam Tanaman Indonesia Sebagai Bahan Fiber Reinforced Composite Kedokteran Gigi, J. Mater. Kedokt. Gigi, 2017, 6, 14,  DOI:10.32793/jmkg.v6i1.260.
40. Y. G. Thyavihalli Girijappa, S. Mavinkere Rangappa, J. Parameswaranpillai and S. Siengchin, Natural Fibers as Sustainable and Renewable Resource for Development of Eco-Friendly Composites: A Comprehensive Review, Front. Mater., 2019, 6, 1–14,  DOI:10.3389/fmats.2019.00226.
41. J. Berger, The World's Major Fibre Crops: Their Cultivation and Manuring, Zurich: Centre d'Etude de l'Azote, 1969. https://www.cabidigitallibrary.org/doi/full/10.5555/19711702835.
42. S. J. Eichhorn, C. A. Baillie, N. Zafeiropoulos, L. Y. Mwaikambo, M. P. Ansell, A. Dufresne, K. M. Entwistle, P. J. Herrera-Franco, G. C. Escamilla, L. Groom, M. Hughes, C. Hill, T. G. Rials and P. M. Wild, Review: Current international research into cellulosic fibres and composites, J. Mater. Sci., 2001, 36, 2107–2131,  DOI:10.1023/A:1017512029696.
43. B. Santoso, Peluang Pengembangan Agave Sebagai Sumber Serat Alam, Perspekt. Rev. Penelit. Tanam. Ind., 2009, 8(2), 84–95,  DOI:10.21082/p.v8n2.2009.%25p.
44. I. R. Maria Widyastuti and L. Lusy, Indonesian Kenaf Fiber Export Potential As A Raw Material For Various Industry, Int. J. Econ. Res., 2022, 6, 9.
45. R. Atav, P. Unal, B. Buzol Mulayim, Ş. Ozturk, C. Kazan and F. Karaaslan, Determination of the Most Commonly Recognized and Used Keratin Based Luxury Fibers, J. Nat. Fibers, 2015, 12, 169–184,  DOI:10.1080/15440478.2014.912971.
46. A. Mishra, N. K. Kim and D. Bhattacharyya, Keratinous Natural Fibres as Sustainable Flame Retardants and Reinforcements in Polymer Composites, J. Compos. Sci., 2024, 8, 230,  DOI:10.3390/jcs8060230.
47. A. Aryal and C. Morley, Mitigation of Contamination and Health Risk: Asbestos Management and Regulatory Practices, Sustainability, 2024, 16, 9740,  DOI:10.3390/su16229740.
48. A. Aryal and C. Morley, Call for a global ban policy on and scientific management of asbestos to eliminate asbestos-related diseases, J. Public Health Policy, 2020, 41, 279–285,  DOI:10.1057/s41271-020-00223-4.
49. L. Stayner, L. S. Welch and R. Lemen, The Worldwide Pandemic of Asbestos-Related Diseases, Annu. Rev. Publ. Health, 2013, 34, 205–216,  DOI:10.1146/annurev-publhealth-031811-124704.
50. J. Li, Q. Dong, K. Yu and L. Liu, Asbestos and asbestos waste management in the Asian-Pacific region: trends, challenges and solutions, J. Cleaner Prod., 2014, 81, 218–226,  DOI:10.1016/j.jclepro.2014.06.022.
51. J. Bauer and M. Bundschuh, Asbest aus globaler Perspektive, Zentralblatt für Arbeitsmed. Arbeitsschutz Ergon., 2016, 66, 376–378,  DOI:10.1007/s40664-016-0141-5.
52. P. Tripathy and S. Biswas, Mechanical and thermal properties of mineral fiber based polymeric nanocomposites: a review, Polym.-Plast. Technol. Mater., 2022, 61, 1385–1410,  DOI:10.1080/25740881.2022.2061996.
53. I. R. Chowdhury, R. Pemberton and J. Summerscales, Developments and Industrial Applications of Basalt Fibre Reinforced Composite Materials, J. Compos. Sci., 2022, 6, 367,  DOI:10.3390/jcs6120367.
54. Y. Kishor Sharma, A. Meena, M. Sahu and A. Dalai, Experimental investigation on mechanical and thermal characteristics of waste sheep wool fiber-filled epoxy composites, Polym.-Plast. Technol. Mater., 2023, 1–17,  DOI:10.1016/j.matpr.2023.01.157.
55. T. Khan, M. T. Bin Hameed Sultan and A. H. Ariffin, The challenges of natural fiber in manufacturing, material selection, and technology application: A review, J. Reinf. Plast. Compos., 2018, 37, 770–779,  DOI:10.1177/0731684418756762.
56. T. Sathishkumar, P. Navaneethakrishnan, S. Shankar, R. Rajasekar and N. Rajini, Characterization of natural fiber and composites – A review, J. Reinf. Plast. Compos., 2013, 32, 1457–1476,  DOI:10.1177/0731684413495322.
57. P. K. Singh, A. Jodhani and A. P. Singh, Bamboo as Construction Material and Bamboo Reinforcement, Int. J Struct. Civ. Eng. Res., 2016, 4, 312–323.
58. M. C. Branciforti, A. L. Marinelli, M. Kobayashi, J. D. Ambrosio, M. R. Monteiro and A. D. Nobre, Wood Polymer Composites Technology Supporting the Recovery and Protection of Tropical Forests: The Amazonian Phoenix Project, Sustainability, 2009, 1, 1431–1443,  DOI:10.3390/su1041431.
59. C. P. Singh, R. V. Patel, M. F. Hasan, A. Yadav, V. Kumar and A. Kumar, Fabrication and evaluation of physical and mechanical properties of jute and coconut coir reinforced polymer matrix composite, Polym.-Plast. Technol. Mater., 2021, 38, 2572–2577,  DOI:10.1016/j.matpr.2020.07.684.
60. K. H. Hong, Preparation and properties of multi-functional cotton fabric treated by gallnut extract, Text. Res. J., 2014, 84, 1138–1146,  DOI:10.1177/0040517513519007.
61. I. G. P. Agus Suryawan, N. P. G. Suardana, I. N. Suprapta Winaya, I. W. Budiarsa Suyasa and T. G. Tirta Nindhia, Study of stinging nettle (urtica dioica l.) Fibers reinforced green composite materials : a review, IOP Conf. Ser.:Mater. Sci. Eng., 2017, 201, 012001,  DOI:10.1088/1757-899X/201/1/012001.
62. A. Shahzad, Hemp fiber and its composites – a review, J. Compos. Mater., 2012, 46, 973–986,  DOI:10.1177/0021998311413623.
63. G. W. Beckermann and K. L. Pickering, Engineering and evaluation of hemp fibre reinforced polypropylene composites: Fibre treatment and matrix modification, Composites, Part A, 2008, 39, 979–988,  DOI:10.1016/j.compositesa.2008.03.010.
64. Ş. Yildizhan, A. Çalik, M. Özcanli and H. Serin, Bio-composite materials: a short review of recent trends, mechanical and chemical properties, and applications, Eur. Mech. Sci., 2018, 2, 83–91,  DOI:10.26701/ems.369005.
65. D. Dai and M. Fan, Wood fibres as reinforcements in natural fibre composites: structure, properties, processing and applications, in. Natural Fibre Composites, Elsevier, 2014: pp. 3–65,  DOI:10.1533/9780857099228.1.3.
66. J. O. Ighalo, C. A. Adeyanju, S. Ogunniyi, A. G. Adeniyi and S. A. Abdulkareem, An empirical review of the recent advances in treatment of natural fibers for reinforced plastic composites, Compos. Interfaces, 2021, 28, 925–960,  DOI:10.1080/09276440.2020.1826274.
67. S. Ochi, Mechanical properties of kenaf fibers and kenaf/PLA composites, Mech. Mater., 2008, 40, 446–452,  DOI:10.1016/j.mechmat.2007.10.006.
68. S. Shibata, Y. Cao and I. Fukumoto, Press forming of short natural fiber-reinforced biodegradable resin: Effects of fiber volume and length on flexural properties, Polym. Test., 2005, 24, 1005–1011,  DOI:10.1016/j.polymertesting.2005.07.012.
69. S. Ugochukwu, M. J. M. Ridzuan, M. S. A. Majid, E. M. Cheng, A. Z. A. Firdaus and N. Marsi, Influence of distilled water and alkaline solution on the scratch resistance properties of Napier fibre filled epoxy (NFFE) composites, J. Mater. Res. Technol., 2020, 9, 14412–14424,  DOI:10.1016/j.jmrt.2020.10.059.
70. I. D. Ibrahim, T. Jamiru, E. R. Sadiku, W. K. Kupolati and S. C. Agwuncha, Impact of Surface Modification and Nanoparticle on Sisal Fiber Reinforced Polypropylene Nanocomposites, J. Nanotechnol., 2016, 2016, 1–9,  DOI:10.1155/2016/4235975.
71. E. Bodros and C. Baley, Study of the tensile properties of stinging nettle fibres (Urtica dioica), Mater. Lett., 2008, 62, 2143–2145,  DOI:10.1016/j.matlet.2007.11.034.
72. A. Ticoalu, T. Aravinthan and F. Cardona, A review on the characteristics of gomuti fibre and its composites with thermoset resins, J. Reinf. Plast. Compos., 2013, 32, 124–136,  DOI:10.1177/0731684412463109.
73. Y. O. Abiodun and A. A. Jimoh, Microstructural characterisation, physical and chemical properties of rice husk ash as viable Pozzolan in building material: a case study of some Nigerian grown rice varieties, Niger. J. Technol., 2018, 37, 71,  DOI:10.4314/njt.v37i1.10.
74. É. Hillig, E. Freire, A. J. Zattera, G. Zanoto, K. Grison and M. Zeni, Use of Sawdust in Polyethylene Composites, Prog. Rubber Plast. Recycl. Technol., 2008, 24, 113–119,  DOI:10.1177/147776060802400202.
75. M. Stasiak, M. Molenda, M. Bańda and E. Gondek, Mechanical properties of sawdust and woodchips, Fuel, 2015, 159, 900–908,  DOI:10.1016/j.fuel.2015.07.044.
76. D. Jankowska, A. Wyrostek, B. Patkowska–Sokoła and K. Czyż, Comparison of Physico-mechanical Properties of Fibre and Yarn Made of Alpaca, Sheep, and Goat Wool, J. Nat. Fibers, 2021, 18, 1512–1517,  DOI:10.1080/15440478.2019.1691126.
77. H.-Y. Cheung, K.-T. Lau, M.-P. Ho and A. Mosallam, Study on the Mechanical Properties of Different Silkworm Silk Fibers, J. Compos. Mater., 2009, 43, 2521–2531,  DOI:10.1177/0021998309345347.
78. R. ZUKOWSKI and R. GAZE, Tensile Strength of Asbestos, Nature, 1959, 183, 35–37,  DOI:10.1038/183035b0.
79. J. Biagiotti, D. Puglia and J. M. Kenny, A Review on Natural Fibre-Based Composites-Part I, J. Nat. Fibers, 2004, 1, 37–68,  DOI:10.1300/J395v01n02_04.
80. L. Yan, N. Chouw and K. Jayaraman, Flax fibre and its composites – A review, Composites, Part B, 2014, 56, 296–317,  DOI:10.1016/j.compositesb.2013.08.014.
81. W. Sujaritjun, P. Uawongsuwan, W. Pivsa-Art and H. Hamada, Mechanical Property of Surface Modified Natural Fiber Reinforced PLA Biocomposites, Energy Procedia, 2013, 34, 664–672,  DOI:10.1016/j.egypro.2013.06.798.
82. O. S. Abiola, W. K. Kupolati, E. R. Sadiku and J. M. Ndambuki, Utilisation of natural fibre as modifier in bituminous mixes: A review, Constr. Build. Mater., 2014, 54, 305–312,  DOI:10.1016/j.conbuildmat.2013.12.037.
83. H. Danso, D. B. Martinson, M. Ali and J. B. Williams, Physical, mechanical and durability properties of soil building blocks reinforced with natural fibres, Constr. Build. Mater., 2015, 101, 797–809,  DOI:10.1016/j.conbuildmat.2015.10.069.
84. H. Hargitai, I. Rácz and R. D. Anandjiwala, Development of HEMP Fiber Reinforced Polypropylene Composites, J. Thermoplast. Compos. Mater., 2008, 21, 165–174,  DOI:10.1177/0892705707083949.
85. M. Asim, K. Abdan, M. Jawaid, M. Nasir, Z. Dashtizadeh, M. R. Ishak and M. E. Hoque, A Review on Pineapple Leaves Fibre and Its Composites, Int. J. Polym. Sci., 2015, 2015, 1–16,  DOI:10.1155/2015/950567.
86. P. Wambua, J. Ivens and I. Verpoest, Natural fibres: can they replace glass in fibre reinforced plastics?, Compos. Sci. Technol., 2003, 63, 1259–1264,  DOI:10.1016/S0266-3538(03)00096-4.
87. N. Saba, M. T. Paridah and M. Jawaid, Mechanical properties of kenaf fibre reinforced polymer composite: A review, Constr. Build. Mater., 2015, 76, 87–96,  DOI:10.1016/j.conbuildmat.2014.11.043.
88. K. Oksman, M. Skrifvars and J.-F. Selin, Natural fibres as reinforcement in polylactic acid (PLA) composites, Compos. Sci. Technol., 2003, 63, 1317–1324,  DOI:10.1016/S0266-3538(03)00103-9.
89. G. Cicala, G. Cristaldi, G. Recca and A. Latteri, Composites Based on Natural Fibre Fabrics, in. Woven Fabric Engineering, Sciyo, 2010,  DOI:10.5772/10465.
90. Y. Zhang, Y. Li, H. Ma and T. Yu, Tensile and interfacial properties of unidirectional flax/glass fiber reinforced hybrid composites, Compos. Sci. Technol., 2013, 88, 172–177,  DOI:10.1016/j.compscitech.2013.08.037.
91. K. L. Pickering, M. G. A. Efendy and T. M. Le, A review of recent developments in natural fibre composites and their mechanical performance, Composites, Part A, 2016, 83, 98–112,  DOI:10.1016/j.compositesa.2015.08.038.
92. A. K. Bledzki and A. Jaszkiewicz, Mechanical performance of biocomposites based on PLA and PHBV reinforced with natural fibres – A comparative study to PP, Compos. Sci. Technol., 2010, 70, 1687–1696,  DOI:10.1016/j.compscitech.2010.06.005.
93. A. Constante, S. Pillay, H. Ning and U. K. Vaidya, Utilization of algae blooms as a source of natural fibers for biocomposite materials: Study of morphology and mechanical performance of Lyngbya fibers, Algal Res., 2015, 12, 412–420,  DOI:10.1016/j.algal.2015.10.005.
94. J. George, M. S. Sreekala and S. Thomas, A review on interface modification and characterization of natural fiber reinforced plastic composites, Polym. Eng. Sci., 2001, 41, 1471–1485,  DOI:10.1002/pen.10846.
95. M. F. M. Alkbir, S. M. Sapuan, A. A. Nuraini and M. R. Ishak, Fibre properties and crashworthiness parameters of natural fibre-reinforced composite structure: A literature review, Compos. Struct., 2016, 148, 59–73,  DOI:10.1016/j.compstruct.2016.01.098.
96. J. Manivannan, S. Rajesh, K. Mayandi, N. Rajini, S. O. Ismail, F. Mohammad, M. K. Kuzman and H. A. Al-Lohedan, Animal fiber characterization and fiber loading effect on mechanical behaviors of sheep wool fiber reinforced polyester composites, J. Nat. Fibers, 2022, 19, 4007–4023,  DOI:10.1080/15440478.2020.1848743.
97. S. Umamageshwari, et.al., Evaluation On Natural Fibers And Its Properties, Turk. J. Comput. Math. Educ., 2021, 12, 1590–1592,  DOI:10.17762/turcomat.v12i11.6088.
98. A. Folino, A. Karageorgiou, P. S. Calabrò and D. Komilis, Biodegradation of Wasted Bioplastics in Natural and Industrial Environments: A Review, Sustainability, 2020, 12, 6030,  DOI:10.3390/su12156030.
99. R. Nagamine, K. Kobayashi, R. Kusumi and M. Wada, Cellulose fiber biodegradation in natural waters: river water, brackish water, and seawater, Cellulose, 2022, 29, 2917–2926,  DOI:10.1007/s10570-021-04349-w.
100. Y. Sun, J. Luo, A. Q. Ni, Y. Y. Bi and W. D. Yu, Study on Biodegradability of Wool and PLA Fibers in Natural Soil and Aqueous Medium, Adv. Mater. Res., 2013, 641–642, 82–86,  DOI:10.4028/www.scientific.net/AMR.641-642.82.
101. B. Tomšič, D. Marković, V. Janković, B. Simončič, J. Nikodinovic-Runic, T. Ilic-Tomic and M. Radetić, Biodegradation of cellulose fibers functionalized with CuO/Cu2O nanoparticles in combination with polycarboxylic acids, Cellulose, 2022, 29, 287–302,  DOI:10.1007/s10570-021-04296-6.
102. Q. Li, L. Ibrahim, W. Zhou, M. Zhang and Z. Yuan, Treatment methods for plant fibers for use as reinforcement in cement-based materials, Cellulose, 2021, 28, 5257–5268,  DOI:10.1007/s10570-021-03903-w.
103. I. Saif, E.-S. Salama, M. Usman, D. S. Lee, K. Malik, P. Liu and X. Li, Improved digestibility and biogas production from lignocellulosic biomass: Biochar addition and microbial response, Ind. Crops Prod., 2021, 171, 113851,  DOI:10.1016/j.indcrop.2021.113851.
104. Y. Sun, J. Luo, A. Q. Ni, Y. Y. Bi and W. D. Yu, Study on Biodegradability of Wool and PLA Fibers in Natural Soil and Aqueous Medium, Adv. Mater. Res., 2013, 641–642, 82–86,  DOI:10.4028/www.scientific.net/AMR.641-642.82.
105. S. Collie, P. Brorens, M. Hassan and I. Fowler, Biodegradation behavior of wool and other textile fibers in aerobic composting conditions, Int. J. Sci. Environ. Technol., 2025, 22, 2113–2125,  DOI:10.1007/s13762-024-05802-6.
106. K. Z. Alzarieni, O. M. Alzoubi, A. A. Jaber and A. Zayed, Characterization of a novel natural cellulosic fiber obtained from the fruit of Tipuana tipu, Biomass Convers. Biorefinery, 2025, 15, 6163–6174,  DOI:10.1007/s13399-024-05414-7.
107. R. Brunšek, D. Kopitar, I. Schwarz and P. Marasović, Biodegradation Properties of Cellulose Fibers and PLA Biopolymer, Polymers, 2023, 15, 3532,  DOI:10.3390/polym15173532.
108. R. Nagamine, K. Kobayashi, R. Kusumi and M. Wada, Cellulose fiber biodegradation in natural waters: river water, brackish water, and seawater, Cellulose, 2022, 29, 2917–2926,  DOI:10.1007/s10570-021-04349-w.
109. W. Phamonpon, J. P. Hinestroza, P. Puthongkham and N. Rodthongkum, Surface-engineered natural fibers: Emerging alternative substrates for chemical sensor applications: A review, Int. J. Biol. Macromol., 2024, 269, 132185,  DOI:10.1016/j.ijbiomac.2024.132185.
110. D. Thapliyal, S. Verma, P. Sen, R. Kumar, A. Thakur, A. K. Tiwari, D. Singh, G. D. Verros and R. K. Arya, Natural Fibers Composites: Origin, Importance, Consumption Pattern, and Challenges, J. Compos. Sci., 2023, 7, 506,  DOI:10.3390/jcs7120506.
111. T. Eleutério, M. J. Trota, M. G. Meirelles and H. C. Vasconcelos, A Review of Natural Fibers: Classification, Composition, Extraction, Treatments, and Applications, Fibers, 2025, 13, 119,  DOI:10.3390/fib13090119.
112. A. Etale, A. J. Onyianta, S. R. Turner and S. J. Eichhorn, Cellulose: A Review of Water Interactions, Applications in Composites, and Water Treatment, Chem. Rev., 2023, 123, 2016–2048,  DOI:10.1021/acs.chemrev.2c00477.
113. M. Simon, R. Fulchiron and F. Gouanvé, Water Sorption and Mechanical Properties of Cellulosic Derivative Fibers, Polymers, 2022, 14, 2836,  DOI:10.3390/polym14142836.
114. J. Lucenius, J. J. Valle-Delgado, K. Parikka and M. Österberg, Understanding hemicellulose-cellulose interactions in cellulose nanofibril-based composites, J. Colloid Interface Sci., 2019, 555, 104–114,  DOI:10.1016/j.jcis.2019.07.053.
115. Y. Jin, J. Lin, Y. Cheng and C. Lu, Lignin-Based High-Performance Fibers by Textile Spinning Techniques, Materials, 2021, 14, 3378,  DOI:10.3390/ma14123378.
116. C. Vasile and M. Baican, Lignins as Promising Renewable Biopolymers and Bioactive Compounds for High-Performance Materials, Polymers, 2023, 15, 3177,  DOI:10.3390/polym15153177.
117. D. Divya, S. Y. Devi, S. Indran, S. Raja and K. R. Sumesh, Extraction and modification of natural plant fibers—A comprehensive review, in. Plant Fibers, their Composites, and Applications, Elsevier, 2022, pp. 25–50,  DOI:10.1016/B978-0-12-824528-6.00002-3.
118. M. R. Sanjay, G. R. Arpitha, L. L. Naik, K. Gopalakrishna and B. Yogesha, Applications of Natural Fibers and Its Composites: An Overview, Nat. Resour., 2016, 07, 108–114,  DOI:10.4236/nr.2016.73011.
119. R. Kumar, M. I. Ul Haq, A. Raina and A. Anand, Industrial applications of natural fibre-reinforced polymer composites – challenges and opportunities, Int. J. Sustain. Eng., 2019, 12, 212–220,  DOI:10.1080/19397038.2018.1538267.
120. R. Kozlowski, M. Wladyka-Przybylak, M. Helwig and K. Kurzydłoski, Composites Based on Lignocellulosic Raw Materials, Mol. Cryst. Liq. Cryst., 2004, 418, 131–151,  DOI:10.1080/15421400490479217.
121. A. R. Pai and R. N. Jagtap, Surface Morphology & Mechanical properties of some unique Natural Fiber Reinforced Polymer Composites- A Review, J. Mater. Environ. Sci., 2015, 6, 902–917 . http://www.jmaterenvironsci.com/Document/vol6/vol6_N4/106-JMES-869-2014-Pai.pdf.
122. P. Peças, H. Carvalho, H. Salman and M. Leite, Natural Fibre Composites and Their Applications: A Review, J. Compos. Sci., 2018, 2, 66,  DOI:10.3390/jcs2040066.
123. U. Mawkhlieng and A. Majumdar, Soft body armour, Text. Prog., 2019, 51, 139–224,  DOI:10.1080/00405167.2019.1692583.
124. S. H. Kamarudin, M. S. Mohd Basri, M. Rayung, F. Abu, S. Ahmad, M. N. Norizan, S. Osman, N. Sarifuddin, M. S. Z. M. Desa, U. H. Abdullah, I. S. Mohamed Amin Tawakkal and L. C. Abdullah, A Review on Natural Fiber Reinforced Polymer Composites (NFRPC) for Sustainable Industrial Applications, Polymers, 2022, 14, 3698,  DOI:10.3390/polym14173698.
125. M. A. Al Faruque, M. Salauddin, M. M. Raihan, I. Z. Chowdhury, F. Ahmed and S. S. Shimo, Bast Fiber Reinforced Green Polymer Composites: A Review on Their Classification, Properties, and Applications, J. Nat. Fibers, 2022, 19, 8006–8021,  DOI:10.1080/15440478.2021.1958431.
126. G. Kannan and R. Thangaraju, Recent Progress on Natural Lignocellulosic Fiber Reinforced Polymer Composites: A Review, J. Nat. Fibers, 2022, 19, 7100–7131,  DOI:10.1080/15440478.2021.1944425.
127. P. Manimaran, S. P. Saravanan and M. Prithiviraj, Investigation of Physico Chemical Properties and Characterization of New Natural Cellulosic Fibers from the Bark of Ficus Racemosa, J. Nat. Fibers, 2021, 18, 274–284,  DOI:10.1080/15440478.2019.1621233.
128. P. Manimaran, S. S. Saravanakumar, N. K. Mithun and P. Senthamaraikannan, Physicochemical properties of new cellulosic fibers from the bark of Acacia arabica, Int. J. Polym. Anal. Charact., 2016, 21, 548–553,  DOI:10.1080/1023666X.2016.1177699.
129. M. Selvaraj, N. Pannirselvam, P. T. Ravichandran, B. Mylsamy and S. Samson, Extraction and Characterization of a New Natural Cellulosic Fiber from Bark of Ficus Carica Plant as Potential Reinforcement for Polymer Composites, J. Nat. Fibers, 2023, 20(2), 1–10,  DOI:10.1080/15440478.2023.2194699.
130. F. Costa, R. Silva and A. R. Boccaccini, Fibrous protein-based biomaterials (silk, keratin, elastin, and resilin proteins) for tissue regeneration and repair, in. Peptides and Proteins as Biomaterials for Tissue Regeneration and Repair, Elsevier, 2018, pp. 175–204,  DOI:10.1016/B978-0-08-100803-4.00007-3.
131. H. Mohit and V. Arul Mozhi Selvan, A comprehensive review on surface modification, structure interface and bonding mechanism of plant cellulose fiber reinforced polymer based composites, Compos. Interfaces, 2018, 25, 629–667,  DOI:10.1080/09276440.2018.1444832.
132. A. Gholampour and T. Ozbakkaloglu, A review of natural fiber composites: properties, modification and processing techniques, characterization, applications, J. Mater. Sci., 2020, 55, 829–892,  DOI:10.1007/s10853-019-03990-y.
133. M. Asim, M. T. Paridah, M. Chandrasekar, R. M. Shahroze, M. Jawaid, M. Nasir and R. Siakeng, Thermal stability of natural fibers and their polymer composites, Iran. Polym. J., 2020, 29, 625–648,  DOI:10.1007/s13726-020-00824-6.
134. H. Yang, B. Yu, X. Xu, S. Bourbigot, H. Wang and P. Song, Lignin-derived bio-based flame retardants toward high-performance sustainable polymeric materials, Green Chem., 2020, 22, 2129–2161,  10.1039/D0GC00449A.
135. A. R. Mankar, A. Modak and K. K. Pant, Recent Advances in the Valorization of Lignin: A Key Focus on Pretreatment, Characterization, and Catalytic Depolymerization Strategies for Future Biorefineries, Adv. Sustain. Syst., 2022, 6, 1–25,  DOI:10.1002/adsu.202100299.
136. J. S. S. Neto, H. F. M. de Queiroz, R. A. A. Aguiar and M. D. Banea, A Review on the Thermal Characterisation of Natural and Hybrid Fiber Composites, Polymers, 2021, 13, 4425,  DOI:10.3390/polym13244425.
137. C. Piña Ramírez, A. Vidales Barriguete, R. Serrano Somolinos, M. del Río Merino and E. Atanes Sánchez, Analysis of fire resistance of cement mortars with mineral wool from recycling, Constr. Build. Mater., 2020, 265, 120349,  DOI:10.1016/j.conbuildmat.2020.120349.
138. Q. Liu, K. Yan, J. Chen, M. Xia, M. Li, K. Liu, D. Wang, C. Wu and Y. Xie, Recent advances in novel aerogels through the hybrid aggregation of inorganic nanomaterials and polymeric fibers for thermal insulation, Aggregate, 2021, 2(e30), 1–27,  DOI:10.1002/agt2.30.
139. F. D'Acierno, C. A. Michal and M. J. MacLachlan, Thermal Stability of Cellulose Nanomaterials, Chem. Rev., 2023, 123, 7295–7325,  DOI:10.1021/acs.chemrev.2c00816.
140. Y. Vankov, E. Bazukova, D. Emelyanov, A. Fedyukhin, O. Afanaseva, I. Akhmetova and U. Berardi, Experimental Assessment of the Thermal Conductivity of Basalt Fibres at High Temperatures, Energies, 2022, 15, 2784,  DOI:10.3390/en15082784.
141. E. R. Bazukova, Y. V. Vankov, S. O. Gaponenko and N. N. Smirnov, Study of thermal conductivity coefficient of basalt fiber insulation at various temperature conditions, Vestn. IGEU, 2021, 15–24,  DOI:10.17588/2072-2672.2021.4.015-024.
142. X. Lian, L. Tian, Z. Li and X. Zhao, Thermal conductivity analysis of natural fiber-derived porous thermal insulation materials, Int. J. Heat Mass Tran., 2024, 220, 124941,  DOI:10.1016/j.ijheatmasstransfer.2023.124941.
143. A. Reizabal, C. M. Costa, L. Pérez-Álvarez, J. L. Vilas-Vilela and S. Lanceros-Méndez, Silk Fibroin as Sustainable Advanced Material: Material Properties and Characteristics, Processing, and Applications, Adv. Funct. Mater., 2023, 33(3), 2210764,  DOI:10.1002/adfm.202210764.
144. S. G. Giteru, D. H. Ramsey, Y. Hou, L. Cong, A. Mohan and A. E. A. Bekhit, Wool keratin as a novel alternative protein: A comprehensive review of extraction, purification, nutrition, safety, and food applications, Compr. Rev. Food Sci. Food Saf., 2023, 22, 643–687,  DOI:10.1111/1541-4337.13087.
145. H. Jamshaid, R. K. Mishra, V. Chandan, S. Nazari, M. Shoaib, L. Bizet, T. A. Ivanova, M. Muller and P. Valasek, Mechanical and Thermo-Mechanical Performance of Natural Fiber-Based Single-Ply and 2-Ply Woven Prepregs, Polymers, 2023, 15, 994,  DOI:10.3390/polym15040994.
146. X. Zhang, S. Zhang and S. Xin, Performance Test and Thermal Insulation Effect Analysis of Basalt-Fiber Concrete, Materials, 2022, 15, 8236,  DOI:10.3390/ma15228236.
147. Y. Li, X. Yi, T. Yu and G. Xian, An overview of structural-functional-integrated composites based on the hierarchical microstructures of plant fibers, Adv. Compos. Hybrid Mater., 2018, 1, 231–246,  DOI:10.1007/s42114-017-0020-3.
148. Y. N. Saravanakumar, N. K. Chandran and M. T. H. Sultan, Recent developments in natural fibre-reinforced polymer biocomposites for future sustainability and key challenges: A review, in. Damage Analysis of Natural Fiber-reinforced Polymer Biocomposites, Elsevier, 2026, pp. 3–20,  DOI:10.1016/B978-0-443-28858-6.00005-3.
149. I. Chakraborty, S. Rongpipi, I. Govindaraju, R. B, S. S. Mal, E. W. Gomez, E. D. Gomez, R. D. Kalita, Y. Nath and N. Mazumder, An insight into microscopy and analytical techniques for morphological, structural, chemical, and thermal characterization of cellulose, Microsc. Res. Tech., 2022, 85, 1990–2015,  DOI:10.1002/jemt.24057.
150. U. K. Sanivada, G. Mármol, F. P. Brito and R. Fangueiro, PLA Composites Reinforced with Flax and Jute Fibers—A Review of Recent Trends, Processing Parameters and Mechanical Properties, Polymers, 2020, 12, 2373,  DOI:10.3390/polym12102373.
151. C. H. Lee, A. Khalina and S. H. Lee, Importance of Interfacial Adhesion Condition on Characterization of Plant-Fiber-Reinforced Polymer Composites: A Review, Polymers, 2021, 13, 438,  DOI:10.3390/polym13030438.
152. M. Grzelec, S. Haas and A. Helman-Ważny, Application of scanning small-angle X-ray scattering in the identification of sheet formation techniques in historical papers, Appl. Phys. A, 2025, 131, 62,  DOI:10.1007/s00339-024-08157-4.
153. D. Agustini, F. R. Caetano, R. F. Quero, J. A. Fracassi da Silva, M. F. Bergamini, L. H. Marcolino-Junior and D. P. de Jesus, Microfluidic devices based on textile threads for analytical applications: state of the art and prospects, Anal. Methods, 2021, 13, 4830–4857,  10.1039/D1AY01337H.
154. D. Papkov, N. Delpouve, L. Delbreilh, S. Araujo, T. Stockdale, S. Mamedov, K. Maleckis, Y. Zou, M. N. Andalib, E. Dargent, V. P. Dravid, M. V. Holt, C. Pellerin and Y. A. Dzenis, Quantifying Polymer Chain Orientation in Strong and Tough Nanofibers with Low Crystallinity: Toward Next Generation Nanostructured Superfibers, ACS Nano, 2019, 13, 4893–4927,  DOI:10.1021/acsnano.8b08725.
155. N. Bystriakova and V. Kapos, Bamboo diversity: the need for a Red List review, Biodiversity, 2005, 6, 12–16,  DOI:10.1080/14888386.2005.9712780.
156. L. Nayak and S. P. Mishra, Prospect of bamboo as a renewable textile fiber, historical overview, labeling, controversies and regulation, Fash. Text., 2016, 3, 2,  DOI:10.1186/s40691-015-0054-5.
157. H. P. S. Abdul Khalil, I. U. H. Bhat, M. Jawaid, A. Zaidon, D. Hermawan and Y. S. Hadi, Bamboo fibre reinforced biocomposites: A review, Mater. Des., 2012, 42, 353–368,  DOI:10.1016/j.matdes.2012.06.015.
158. Y. Sheng, B. Zhang, Y. Yan, H. Li, Z. Chen and H. Chen, Laboratory Investigation on the Use of Bamboo Fiber in Asphalt Mixtures for Enhanced Performance, Arab. J. Sci. Eng., 2019, 44, 4629–4638,  DOI:10.1007/s13369-018-3490-x.
159. C. Xia, C. Wu, K. Liu and K. Jiang, Study on the Durability of Bamboo Fiber Asphalt Mixture, Materials, 2021, 14, 1667,  DOI:10.3390/ma14071667.
160. H. Jia, H. Chen, Y. Sheng, J. Meng, S. Cui, Y. R. Kim, S. Huang and H. Qin, Effect of laboratory aging on the stiffness and fatigue cracking of asphalt mixture containing bamboo fiber, J. Cleaner Prod., 2022, 333, 130120,  DOI:10.1016/j.jclepro.2021.130120.
161. P. K. Kushwaha and R. Kumar, Influence of chemical treatments on the mechanical and water absorption properties of bamboo fiber composites, J. Reinf. Plast. Compos., 2011, 30, 73–85,  DOI:10.1177/0731684410383064.
162. D. Yu, A. Jia, C. Feng, W. Liu, T. Fu and R. Qiu, Preparation and mechanical properties of asphalt mixtures reinforced by modified bamboo fibers, Constr. Build. Mater., 2021, 286, 122984,  DOI:10.1016/j.conbuildmat.2021.122984.
163. A. G. Adeniyi, D. V. Onifade, J. O. Ighalo and A. S. Adeoye, A review of coir fiber reinforced polymer composites, Composites, Part B, 2019, 176, 107305,  DOI:10.1016/j.compositesb.2019.107305.
164. S. Siddika, F. Mansura, M. Hasan and A. Hassan, Effect of reinforcement and chemical treatment of fiber on The Properties of jute-coir fiber reinforced hybrid polypropylene composites, Fibers Polym., 2014, 15, 1023–1028,  DOI:10.1007/s12221-014-1023-0.
165. P. Sudhakara, D. Jagadeesh, Y. Wang, C. V. Prasad, A. P. K. Devi, G. Balakrishnan, B. S. Kim and J. I. Song, Fabrication of Borassus fruit lignocellulose fiber/PP composites and comparison with jute, sisal and coir fibers, Carbohydr. Polym., 2013, 98, 1002–1010,  DOI:10.1016/j.carbpol.2013.06.080.
166. S. Oda, J. Leomar Fernandes and J. S. Ildefonso, Analysis of use of natural fibers and asphalt rubber binder in discontinuous asphalt mixtures, Constr. Build. Mater., 2011, 26(1), 13–20,  DOI:10.1016/j.conbuildmat.2011.06.030.
167. A. C. do Vale, M. D. T. Casagrande and J. B. Soares, Behavior of Natural Fiber in Stone Matrix Asphalt Mixtures Using Two Design Methods, J. Mater. Civ. Eng., 2014, 26, 457–465,  DOI:10.1061/(ASCE)MT.1943-5533.0000815.
168. Y. Haryati, A. H. Norhidayah, M. Nordiana, A. Juraidah, A. H. N. Hayati, P. J. Ramadhansyah, M. K. Azman and A. Haryati, Stability and rutting resistance of porous asphalt mixture incorporating coconut shells and fibres, IOP Conf. Ser. Earth Environ. Sci., 2019, 244, 012043,  DOI:10.1088/1755-1315/244/1/012043.
169. L. Y. Mwaikambo and M. P. Ansell, Chemical modification of hemp, sisal, jute, and kapok fibers by alkalization, J. Appl. Polym. Sci., 2002, 84, 2222–2234,  DOI:10.1002/app.10460.
170. H. Singh, J. Inder Preet Singh, S. Singh, V. Dhawan and S. Kumar Tiwari, A Brief Review of Jute Fibre and Its Composites, Polym.-Plast. Technol. Mater., 2018, 5, 28427–28437,  DOI:10.1016/j.matpr.2018.10.129.
171. M. A. Fuqua, S. Huo and C. A. Ulven, Natural Fiber Reinforced Composites, Polym. Rev., 2012, 52, 259–320,  DOI:10.1080/15583724.2012.705409.
172. A. A. Muhammad Fawad Rashid, M. F. Hassan and A. Danish, The Effect Of Using Jute Fiber On Deformation Resistance Of Asphalt Concrete, in. Proceedings of the 3rd International Conference on Sustainability in Civil Engineering, Department of Civil Engineering Capital University of Science and Technology, Islamabad Pakistan, 2021, https://www.researchgate.net/publication/353654177_THE_EFFECT_OF_USING_JUTE_FIBER_ON_DEFORMATION_RESISTANCE_OF_ASPHALT_CONCRETE.
173. M. Ismael, M. Y. Fattah and A. F. Jasim, Permanent Deformation Characterization of Stone Matrix Asphalt Reinforced by Different Types of Fibers, J. Eng., 2022, 28, 99–116,  DOI:10.31026/j.eng.2022.02.07.
174. A. Mansourian, A. Razmi and M. Razavi, Evaluation of fracture resistance of warm mix asphalt containing jute fibers, Constr. Build. Mater., 2016, 117, 37–46,  DOI:10.1016/j.conbuildmat.2016.04.128.
175. H. K. Shanbara, F. Ruddock and W. Atherton, A laboratory study of high-performance cold mix asphalt mixtures reinforced with natural and synthetic fibres, Constr. Build. Mater., 2018, 172, 166–175,  DOI:10.1016/j.conbuildmat.2018.03.252.
176. P. S. Mukherjee and K. G. Satyanarayana, Structure and properties of some vegetable fibres, J. Mater. Sci., 1984, 19, 3925–3934,  DOI:10.1007/BF00980755.
177. K. Joseph, S. Thomas and C. Pavithran, Effect of chemical treatment on the tensile properties of short sisal fibre-reinforced polyethylene composites, Polymer, 1996, 37, 5139–5149,  DOI:10.1016/0032-3861(96)00144-9.
178. S. Ramalingam, R. Murugasan and M. N. Nagabhushana, Laboratory performance evaluation of environmentally sustainable sisal fibre reinforced bituminous mixes, Constr. Build. Mater., 2017, 148, 22–29,  DOI:10.1016/j.conbuildmat.2017.05.006.
179. D. Kar, J. P. Giri and M. Panda, Performance Evaluation of Bituminous Paving Mixes Containing Sisal Fiber as an Additive, Transp. Infrastruct. Geotechnol., 2019, 6, 189–206,  DOI:10.1007/s40515-019-00079-6.
180. P. Sahu and M. Gupta, Sisal (Agave sisalana) fibre and its polymer-based composites: A review on current developments, J. Reinf. Plast. Compos., 2017, 36, 1759–1780,  DOI:10.1177/0731684417725584.
181. C. H. Haigler, L. Betancur, M. R. Stiff and J. R. Tuttle, Cotton fiber: a powerful single-cell model for cell wall and cellulose research, Front. Plant Sci., 2012, 3, 104,  DOI:10.3389/fpls.2012.00104.
182. D. J. Hinchliffe, G. N. Thyssen, B. D. Condon, L. Zeng, R. J. Hron, C. A. Madison, J. N. Jenkins, J. C. McCarty, C. D. Delhom and R. Sui, Interrelationships between cotton fiber quality traits and tensile properties of hydroentangled nonwoven fabrics, J. Ind. Text., 2023, 53, 15280837231171312,  DOI:10.1177/15280837231171312.
183. X. Wen, Y. Zhai, L. Zhang, Y. Chen, Z. Zhu, G. Chen, K. Wang and Y. Zhu, Molecular studies of cellulose synthase supercomplex from cotton fiber reveal its unique biochemical properties, Sci. China Life Sci., 2022, 65, 1776–1793,  DOI:10.1007/s11427-022-2083-9.
184. Q. Tang, Y. Chen, M. Du, J. Yu, Z. Li and B. Ding, Research progress in Ramie fiber extraction: Degumming method, working mechanism, and fiber performance, Ind. Crops Prod., 2024, 222, 119876,  DOI:10.1016/j.indcrop.2024.119876.
185. Y. Song, K. Nie, C. Sun, F. Xu, S. Zhang, W. Jiang, Y. Zhang, G. Han, A. Ragauskas and J. Ma, Exploration of the application performance of choline chloride-ethanolamine for the degumming of ramie cellulose fiber, Int. J. Biol. Macromol., 2025, 308, 142554,  DOI:10.1016/j.ijbiomac.2025.142554.
186. M. A. Aristri, W. Hidayat, A. H. Iswanto and M. A. R. Lubis, Ramie Fibers from Agroforestry System as Sustainable Materials for Functional Textiles: A Review, J. Sylva Lestari, 2024, 12, 962–979,  DOI:10.23960/jsl.v12i3.986.
187. H. Huang, Q. Tang, G. Lin, Y. Liu, J. Yu, B. Ding and Z. Li, Anthraquinone-assisted deep eutectic solvent degumming of ramie fibers: Evaluation of fiber properties and degumming performance, Ind. Crops Prod., 2022, 185, 115115,  DOI:10.1016/j.indcrop.2022.115115.
188. D. Biswas, S. K. Chakrabarti, S. De and R. Paral, Eco-Friendly Degumming Technology for Ramie Fiber, J. Nat. Fibers, 2016, 13, 227–237,  DOI:10.1080/15440478.2015.1005327.
189. D. A. G. Vayabari, Z. Ilham, N. Md Saad, S. R. A. Usuldin, D. A. Norhisham, M. H. Abd Rahim and W. A. A. Q. I. Wan-Mohtar, Cultivation Strategies of Kenaf (Hibiscus cannabinus L.) as a Future Approach in Malaysian Agriculture Industry, Horticulturae, 2023, 9(8), 925,  DOI:10.3390/horticulturae9080925.
190. A. B. M. Supian, M. R. M. Asyraf, A. Syamsir, Q. Ma, K. Z. Hazrati, M. N. M. Azlin, M. Mubarak Ali, A. Ghani, L. S. Hua, S. SaifulAzry, M. R. Razman, Z. Ramli, N. M. Nurazzi, M. N. F. Norrrahim and S. M. K. Thiagamani, Kenaf/glass fiber-reinforced polymer composites: Pioneering sustainable materials with enhanced mechanical and tribological properties, Polym. Compos., 2024, 45, 14421–14447,  DOI:10.1002/pc.28785.
191. M. R. M. Asyraf, M. Rafidah, A. Azrina and M. R. Razman, Dynamic mechanical behaviour of kenaf cellulosic fibre biocomposites: a comprehensive review on chemical treatments, Cellulose, 2021, 28, 2675–2695,  DOI:10.1007/s10570-021-03710-3.
192. Y. Huang, M. T. H. Sultan, F. S. Shahar, A. Łukaszewicz, Z. Oksiuta and R. Grzejda, Kenaf Fiber-Reinforced Biocomposites for Marine Applications: A Review, Materials, 2025, 18, 999,  DOI:10.3390/ma18050999.
193. S. B. Boppana, K. Palani Kumar, A. Ponshanmugakumar and S. Dayanand, Different Natural Fiber Reinforced Composites and Its Potential Industrial and Domestic Applications: A Review, in. Bio-Fiber Reinforced Composite Materials, 2022, pp. 51–73,  DOI:10.1007/978-981-16-8899-7_4.
194. N. M. Nurazzi, M. R. M. Asyraf, M. Rayung, M. N. F. Norrrahim, S. S. Shazleen, M. S. A. Rani, A. R. Shafi, H. A. Aisyah, M. H. M. Radzi, F. A. Sabaruddin, R. A. Ilyas, E. S. Zainudin and K. Abdan, Thermogravimetric Analysis Properties of Cellulosic Natural Fiber Polymer Composites: A Review on Influence of Chemical Treatments, Polymers, 2021, 13, 2710,  DOI:10.3390/polym13162710.
195. J. Baraniak and M. Kania-Dobrowolska, Multi-Purpose Utilization of Kapok Fiber and Properties of Ceiba Pentandra Tree in Various Branches of Industry, J. Nat. Fibers, 2023, 20(1), 2192542,  DOI:10.1080/15440478.2023.2192542.
196. Z. Yang, F. Li, F. Guan, F. Wang, C. Wang and Y. Qiu, Mesopore and composition structure of kapok fiber, Cellulose, 2023, 30, 789–799,  DOI:10.1007/s10570-022-04965-0.
197. T. Martina, Novilianoni, D. Mustafa and A. S. Soekoco, Development of core pocket nonwoven utilizing kapok fiber (Ceiba Petandra)-polypropylene for thermal insulation, The 4th International Seminar on Science and Technology, 2025, 3248(1), 020020,  DOI:10.1063/5.0243245.
198. A. J. Cárdenas-Oscanoa, E. Bonaccurso, W. Machunze, M. Euring and K. Zhang, Lightweight Natural Fiber Insulation Boards Produced with Kapok Fiber (Ceiba Pentandra) and Polylactic Acid or Bicomponent Fiber as a Binder, Global chall., 2025, 9(3), 2400310,  DOI:10.1002/gch2.202400310.
199. D. M. F. Sandrini, M. F. Pillis, O. V. Correa, P. Madesh, B. Krishnasamy and D. F. S. Petri, Lecithin/graphite modified kapok fibers for functional xerogel composites, Cellulose, 2024, 31, 8067–8086,  DOI:10.1007/s10570-024-06113-2.
200. C. M. Futalan, A. E. S. Choi, H. G. O. Soriano, M. K. B. Cabacungan and J. C. Millare, Modification Strategies of Kapok Fiber Composites and Its Application in the Adsorption of Heavy Metal Ions and Dyes from Aqueous Solutions: A Systematic Review, Int. Res. J. Publ. Environ. Health, 2022, 19, 2703,  DOI:10.3390/ijerph19052703.
201. A. Duangpakdee, S. Kanokpanont, Y. Tabata, C. Laomeephol and S. Damrongsakkul, Natural and treated kapok fibers (Ceiba pentandra): their biocompatibility and enhanced hydrophilicity for cell culture applications, Cellulose, 2025, 32, 7299–7318,  DOI:10.1007/s10570-025-06648-y.
202. S. S. Bhambure, A. S. Rao and T. Senthilkumar, Analysis of Mechanical Properties of Kenaf and Kapok Fiber Reinforced Hybrid Polyester Composite, J. Nat. Fibers, 2023, 20(1), 2156964,  DOI:10.1080/15440478.2022.2156964.
203. R. Das, D. P. Sahu and D. K. Bisoyi, Silane-treated kapok fiber/epoxy composites for aerospace cabin interiors: Synthesis and characterization, Polym. Compos., 2025, 46, 6270–6289,  DOI:10.1002/pc.29359.
204. H. Zhang, J. Wang, G. Xu, Y. Xu, F. Wang and H. Shen, Ultralight, hydrophobic, sustainable, cost-effective and floating kapok/microfibrillated cellulose aerogels as speedy and recyclable oil superabsorbents, J. Hazard. Mater., 2021, 406, 124758,  DOI:10.1016/j.jhazmat.2020.124758.
205. S. Zhu, J. Xie, Q. Sun, Z. Zhang, J. Wan, Z. Zhou, J. Lu, J. Chen, J. Xu, K. Chen and M. Fan, Recent advances on bast fiber composites: Engineering innovations, applications and perspectives, Composites, Part B, 2024, 284, 111738,  DOI:10.1016/j.compositesb.2024.111738.
206. W. Wojtasik, K. Kostyn, M. Preisner, T. Czuj, M. Zimniewska, J. Szopa and M. Wróbel-Kwiatkowska, Cottonization of Decorticated and Degummed Flax Fiber - A Novel Approach to Improving the Quality of Flax Fiber and its Biomedical Applications, J. Nat. Fibers, 2024, 21(1), 2368143,  DOI:10.1080/15440478.2024.2368143.
207. S. Chokshi, V. Parmar, P. Gohil and V. Chaudhary, Chemical Composition and Mechanical Properties of Natural Fibers, J. Nat. Fibers, 2022, 19, 3942–3953,  DOI:10.1080/15440478.2020.1848738.
208. P. Shen, Q. Tang, X. Chen and Z. Li, Nanocrystalline cellulose extracted from bast fibers: Preparation, characterization, and application, Carbohydr. Polym., 2022, 290, 119462,  DOI:10.1016/j.carbpol.2022.119462.
209. F. N. Cleophas, N. Z. Zahari, P. Murugayah, S. A. Rahim and A. N. Mohd Yatim, Phytoremediation: A Novel Approach of Bast Fiber Plants (Hemp, Kenaf, Jute and Flax) for Heavy Metals Decontamination in Soil—Review, Toxics, 2022, 11, 5,  DOI:10.3390/toxics11010005.
210. S. Aldroubi, B. Kasal, L. Yan and E. V. Bachtiar, Multi-scale investigation of morphological, physical and tensile properties of flax single fiber, yarn and unidirectional fabric, Composites, Part B, 2023, 259, 110732,  DOI:10.1016/j.compositesb.2023.110732.
211. L. Samant, A. Goel, J. Mathew, S. Jose and S. Thomas, Effect of surface treatment on flax fiber reinforced natural rubber green composite, J. Appl. Polym. Sci., 2023, 140(3), 10–17,  DOI:10.1002/app.53651.
212. X. Ao, A. Vázquez-López, D. Mocerino, C. González and D.-Y. Wang, Flame retardancy and fire mechanical properties for natural fiber/polymer composite: A review, Composites, Part B, 2024, 268, 111069,  DOI:10.1016/j.compositesb.2023.111069.
213. A. Arbelaiz, U. Txueka, I. Mezo and A. Orue, Biocomposites Based on Poly(Lactic Acid) Matrix and Reinforced with Lignocellulosic Fibers: The Effect of Fiber Type and Matrix Modification, J. Nat. Fibers, 2022, 19, 1–14,  DOI:10.1080/15440478.2020.1726247.
214. Q. Tang, Y. Chen, M. Du, J. Yu, Z. Li and B. Ding, Research progress in Ramie fiber extraction: Degumming method, working mechanism, and fiber performance, Ind. Crops Prod., 2024, 222, 119876,  DOI:10.1016/j.indcrop.2024.119876.
215. W. K. Jeffrey, Physical and Mechanical Properties of Chicken Feather Materials, Georgia Institute of Technology, 2006, https://repository.gatech.edu/server/api/core/bitstreams/f613f121-96e3-48c4-b0e3-3c39f453bde7/content.
216. G. Bansal and V. K. Singh, Review on Chicken Feather Fiber (CFF) a Livestock Waste in Composite Material Development, Int. J. Waste Resour., 2016, 06(2), 1000254,  DOI:10.4172/2252-5211.1000254.
217. R. Babalola, A. O. Ayeni, P. S. Joshua, A. A. Ayoola, U. O. Isaac, U. Aniediong, V. E. Efeovbokhan and J. A. Omoleye, Synthesis of thermal insulator using chicken feather fibre in starch-clay nanocomposites, Heliyon, 2020, 6, e05384,  DOI:10.1016/j.heliyon.2020.e05384.
218. T. Bartels, Variations in the morphology, distribution, and arrangement of feathers in domesticated birds, J. Exp. Zool., Part B, 2003, 298, 91–108,  DOI:10.1002/jez.b.28.
219. W. Winandy, E. Jerold, J. H. Muehl, J. A. Micales, A. Raina and Schmidt, Potential of Chicken Feather Fibre in Wood MDF Composites, University of London, 2023, 6, 20, https://research.fs.usda.gov/treesearch/7423.
220. M. Zhan and R. P. Wool, Mechanical properties of chicken feather fibers, Polym. Compos., 2011, 32, 937–944,  DOI:10.1002/pc.21112.
221. S. Huda and Y. Yang, Composites from ground chicken quill and polypropylene, Compos. Sci. Technol., 2008, 68, 790–798,  DOI:10.1016/j.compscitech.2007.08.015.
222. V. Saucedo-Rivalcoba, A. L. Martínez-Hernández, G. Martínez-Barrera, C. Velasco-Santos and V. M. Castaño, (Chicken feathers keratin)/polyurethane membranes, Appl. Phys. A, 2011, 104, 219–228,  DOI:10.1007/s00339-010-6111-4.
223. S. Cheng, K. Lau, T. Liu, Y. Zhao, P.-M. Lam and Y. Yin, Mechanical and thermal properties of chicken feather fiber/PLA green composites, Composites, Part B, 2009, 40, 650–654,  DOI:10.1016/j.compositesb.2009.04.011.
224. J. R. Barone and W. F. Schmidt, Polyethylene reinforced with keratin fibers obtained from chicken feathers, Compos. Sci. Technol., 2005, 65, 173–181,  DOI:10.1016/j.compscitech.2004.06.011.
225. K.-C. Chang, The Archaeology of Ancient China, Yale University Press, 1987.
226. R. F. Foelix, Biology of Spiders, Oxford University Press, New York, Oxford, 2nd edn, 1996.
227. N. V. Bhat and G. S. Nadiger, Crystallinity in silk fibers: Partial acid hydrolysis and related studies, J. Appl. Polym. Sci., 1980, 25, 921–932,  DOI:10.1002/app.1980.070250518.
228. M. Xu and R. V Lewis, Structure of a protein superfiber: spider dragline silk, Proc. Natl. Acad. Sci. U. S. A., 1990, 87, 7120–7124,  DOI:10.1073/pnas.87.18.7120.
229. Y. Yang, X. Chen, Z. Shao, P. Zhou, D. Porter, D. P. Knight and F. Vollrath, Toughness of Spider Silk at High and Low Temperatures, Adv. Mater., 2005, 17, 84–88,  DOI:10.1002/adma.200400344.
230. Y.-Q. Zhang, Applications of natural silk protein sericin in biomaterials, Biotechnol. Adv., 2002, 20, 91–100,  DOI:10.1016/S0734-9750(02)00003-4.
231. S. Putthanarat, N. Stribeck, S. A. Fossey, R. K. Eby and W. W. Adams, Investigation of the nanofibrils of silk fibers, Polymer, 2000, 41, 7735–7747,  DOI:10.1016/S0032-3861(00)00036-7.
232. B. Zhou, Q. Zhou, P. Wang, J. Yuan, Y. Yu, C. Deng, Q. Wang and X. Fan, HRP-mediated graft polymerization of acrylic acid onto silk fibroins and in situ biomimetic mineralization, J. Mater. Sci. Mater. Med., 2018, 29, 72,  DOI:10.1007/s10856-018-6084-y.
233. P. Wang, M. Yu, L. Cui, J. Yuan, Q. Wang and X. Fan, Modification of B ombyx mori silk fabrics by tyrosinase-catalyzed grafting of chitosan, Eng. Life Sci., 2014, 14, 211–217,  DOI:10.1002/elsc.201300008.
234. Q. Lu, B. Zhang, M. Li, B. Zuo, D. L. Kaplan, Y. Huang and H. Zhu, Degradation Mechanism and Control of Silk Fibroin, Biomacromolecules, 2011, 12, 1080–1086,  DOI:10.1021/bm101422j.
235. P. Wang, X. Zhu, J. Yuan, Y. Yu, L. Cui, Y. Duan, Q. Wang and X. Fan, Grafting of tyrosine-containing peptide onto silk fibroin membrane for improving enzymatic reactivity, Fibers Polym., 2016, 17, 1323–1329,  DOI:10.1007/s12221-016-6460-5.
236. M. Feughelman, A Note on the Water-Impenetrable Component of α-Keratin Fibers, Text. Res. J., 1989, 59, 739–742,  DOI:10.1177/004051758905901205.
237. D. Chen, L. Tan, H. Liu, J. Hu, Y. Li and F. Tang, Fabricating Superhydrophilic Wool Fabrics, Langmuir, 2010, 26, 4675–4679,  DOI:10.1021/la903562h.
238. A. Idris, R. Vijayaraghavan, U. A. Rana, A. F. Patti and D. R. MacFarlane, Dissolution and regeneration of wool keratin in ionic liquids, Green Chem., 2014, 16, 2857–2864,  10.1039/C4GC00213J.
239. A. Sukumar and R. Subramanian, Elements in the Hair of Non-Mining Workers of a Lignite Open Mine in Neyveli, Ind. Health, 2003, 41, 63–68,  DOI:10.2486/indhealth.41.63.
240. C. Popescu and H. Höcker, Hair—the most sophisticated biological composite material, Chem. Soc. Rev., 2007, 36, 1282,  10.1039/b604537p.
241. J. Zach, A. Korjenic, V. Petránek, J. Hroudová and T. Bednar, Performance evaluation and research of alternative thermal insulations based on sheep wool, Energy Build., 2012, 49, 246–253,  DOI:10.1016/j.enbuild.2012.02.014.
242. S.-H. Jeon, K.-H. Hwang, J. S. Lee, J.-H. Boo and S. H. Yun, Plasma treatments of wool fiber surface for microfluidic applications, Mater. Res. Bull., 2015, 69, 65–70,  DOI:10.1016/j.materresbull.2015.02.025.
243. L. Cui, J. Gong, X. Fan, P. Wang, Q. Wang and Y. Qiu, Transglutaminase-modified wool keratin film and its potential application in tissue engineering, Eng. Life Sci., 2013, 13, 149–155,  DOI:10.1002/elsc.201100206.
244. B. Caven, B. Redl and T. Bechtold, An investigation into the possible antibacterial properties of wool fibers, Text. Res. J., 2019, 89, 510–516,  DOI:10.1177/0040517517750645.
245. R. M. Salih and A. S. J. Al-Zubaydi, Study of the insulation and mechanical properties of hair-reinforced epoxy, Prog. Rubber Plast. Recycl. Technol., 2021, 37, 247–263,  DOI:10.1177/1477760620958944.
246. F. Wang, A. Zieman and P. A. Coulombe, Skin Keratins, in. Methods in Enzymology, 2016, pp. 303–350,  DOI:10.1016/bs.mie.2015.09.032.
247. C. Cruz, C. Costa, A. Gomes, T. Matamá and A. Cavaco-Paulo, Human Hair and the Impact of Cosmetic Procedures: A Review on Cleansing and Shape-Modulating Cosmetics, Cosmetics, 2016, 3, 26,  DOI:10.3390/cosmetics3030026.
248. P. D. Rao, C. U. Kiran and K. E. Prasad, Tensile Studies on Random Oriented Human Hair Fiber Reinforced Polyester Composites, J. Eng. Mech., 2018, 47, 37–44,  DOI:10.3329/jme.v47i1.35357.
249. G. B. B. D. Senthilnathan, A. Gnanavel Babu and K. Gopinath, Characterization of Glass Fibre – Coconut Coir– Human Hair Hybrid Composites, Int. J. Eng. Technol., 2014, 6, 75–82 ). https://d1wqtxts1xzle7.cloudfront.net/73783317/Characterization_of_Glass_Fibre__Coconut20211028-14514-1lpo46y.pdf?1738445008=%26response-content-disposition=inline%3B+filename%3DCharacterization_of_Glass_Fibre_Coconut.pdf%26Expires=1761023182%26Signature=C1U0QJ.
250. C. R. Robbins, Dyeing Human Hair, in. Chemical and Physical Behavior of Human Hair, Springer Berlin Heidelberg, Berlin, Heidelberg, 2012, pp. 445–488,  DOI:10.1007/978-3-642-25611-0_7.
251. V. Paolini, L. Tomassetti, M. Segreto, D. Borin, F. Liotta, M. Torre and F. Petracchini, Asbestos treatment technologies, J. Mater. Cycles Waste Manag., 2019, 21, 205–226,  DOI:10.1007/s10163-018-0793-7.
252. M. C. Dichicco, M. Paternoster, G. Rizzo and R. Sinisi, Mineralogical Asbestos Assessment in the Southern Apennines (Italy): A Review, Fibers, 2019, 7, 24,  DOI:10.3390/fib7030024.
253. E. R. Sahin and D. Koksal, Asbestos: Mineralogical features and fiber analysis in biological materials, Arch. Environ. Occup. Health, 2023, 78, 369–378,  DOI:10.1080/19338244.2023.2264764.
254. G. M. Militello, L. Gaggero and S. La Maestra, Asbestiform Amphiboles and Cleavage Fragments Analogues: Overview of Critical Dimensions, Aspect Ratios, Exposure and Health Effects, Minerals, 2021, 11, 525,  DOI:10.3390/min11050525.
255. H. Cheng, J. Wang, H. Song, B. Wang and Z. Ma, CO₂ Mineralization Technologies Across Industrial and Geological Settings: Trends and Advances, Min. Metall. Explor., 2025, 42, 3271–3284,  DOI:10.1007/s42461-025-01331-z.
256. M. D. Wright, A. J. Buckley and R. Smith, Estimates of carbon nanotube deposition in the lung: improving quality and robustness, Inhal. Toxicol., 2020, 32, 282–298,  DOI:10.1080/08958378.2020.1785594.
257. D. M. Bernstein, The health effects of short fiber chrysotile and amphibole asbestos, Crit. Rev. Toxicol., 2022, 52, 89–112,  DOI:10.1080/10408444.2022.2056430.
258. G. Gaudino, J. Xue and H. Yang, How asbestos and other fibers cause mesothelioma, Transl. Lung Cancer Res, 2020, 9, S39–S46,  DOI:10.21037/tlcr.2020.02.01.
259. A. Aryal and C. Morley, Call for a global ban policy on and scientific management of asbestos to eliminate asbestos-related diseases, J. Public Health Policy, 2020, 41, 279–285,  DOI:10.1057/s41271-020-00223-4.
260. C. G. Zenebe, A Review on the Role of Wollastonite Biomaterial in Bone Tissue Engineering, BioMed Res. Int., 2022, 2022(1), 4996530,  DOI:10.1155/2022/4996530.
261. O. Myronyuk, D. Baklan, A. Bilousova, I. Byba, A. Minitskyi, Y. Sydorenko and A. Shysholin, Effect of hydroxyl terminated polybutene elasticizing additive on the wear of paper friction material, Polym.-Plast. Technol. Mater., 2025, 64, 1807–1819,  DOI:10.1080/25740881.2025.2480852.
262. J. X. Chan, J. F. Wong, A. Hassan, Z. Mohamad and N. Othman, Mechanical properties of wollastonite reinforced thermoplastic composites: A review, Polym. Compos., 2020, 41, 395–429,  DOI:10.1002/pc.25403.
263. D. Mirindi, J. Hunter, F. Mirindi, D. Sinkhonde and F. Yazdandoust, Structural performance of boards through nanoparticle reinforcement: An advance review, Nanotechnol. Rev., 2024, 13(1), 20240119,  DOI:10.1515/ntrev-2024-0119.
264. M. Dutkiewicz, H. E. Yücel and F. Yıldızhan, Evaluation of the Performance of Different Types of Fibrous Concretes Produced by Using Wollastonite, Materials, 2022, 15, 6904,  DOI:10.3390/ma15196904.
265. J. F. Wong, J. X. Chan, A. bin Hassan, Z. binti Mohamad and N. binti Othman, Thermal and flammability properties of wollastonite-filled thermoplastic composites: a review, J. Mater. Sci., 2021, 56, 8911–8950,  DOI:10.1007/s10853-020-05255-5.
266. P. I. Dolez, S. Marsha and R. H. McQueen, Fibers and Textiles for Personal Protective Equipment: Review of Recent Progress and Perspectives on Future Developments, Textiles, 2022, 2, 349–381,  DOI:10.3390/textiles2020020.
267. J. J. Chruściel, Modifications of Textile Materials with Functional Silanes, Liquid Silicone Softeners, and Silicone Rubbers—A Review, Polymers, 2022, 14, 4382,  DOI:10.3390/polym14204382.
268. Y. Lei, X. Zhao, L. Xu, H. Li, J. Liang, G. H. Yeoh and W. Wang, Natural Flame Retardant Minerals for Advanced Epoxy Composites, Fire, 2024, 7, 308,  DOI:10.3390/fire7090308.
269. D. Zhu, Y. Tang and M. Z. Rahman, Basalt fiber: composites and applications, in. Synthetic and Mineral Fibers, Their Composites and Applications, Elsevier, 2024, pp. 337–361,  DOI:10.1016/B978-0-443-13623-8.00012-5.
270. G. S. Mundhe, P. A. Mahanwar, J. R. Patil and E. S, A Review on Basalt Fiber and Basalt Fiber Reinforced Polymer Composites: Advancement and Industrial Applications, Int. J. Res. Appl. Sci. Eng. Technol., 2023, 11, 1729–1752,  DOI:10.22214/ijraset.2023.50471.
271. M. Zhu, B. Chen, M. Wu and J. Han, Effects of different mixing ratio parameters on mechanical properties of cost-effective green engineered cementitious composites (ECC), Constr. Build. Mater., 2022, 328, 127093,  DOI:10.1016/j.conbuildmat.2022.127093.
272. G. Liu and X. Wang, Advances in Basalt Fiber Reinforced Cement-based Composites: Mechanical Properties and Durability Insights, J. Eng Res. Reports, 2025, 27, 225–231,  DOI:10.9734/jerr/2025/v27i11382.
273. H. Dou, J. Bai, H. Lu, T. Zhang, L. Kong, Z. Bai and W. Li, Effect of TiO2 on preparation condition, mechanical properties and alkali resistance of continuous basalt fibers, Cem. Concr. Compos., 2023, 136, 104861,  DOI:10.1016/j.cemconcomp.2022.104861.
274. A. M. Tahwia, K. A. Helal and O. Youssf, Chopped Basalt Fiber-Reinforced High-Performance Concrete: An Experimental and Analytical Study, J. Compos. Sci., 2023, 7, 250,  DOI:10.3390/jcs7060250.
275. Z. Zhang, S. Cai, Y. Li, Z. Wang, Y. Long, T. Yu and Y. Shen, High performances of plant fiber reinforced composites—A new insight from hierarchical microstructures, Compos. Sci. Technol., 2020, 194, 108151,  DOI:10.1016/j.compscitech.2020.108151.
276. S. Y. Nayak, S. Shenoy Heckadka, A. Seth, S. Prabhu, R. Sharma and K. R. Shenoy, Effect of chemical treatment on the physical and mechanical properties of flax fibers: A comparative assessment, Mater. Today Proc., 2021, 38, 2406–2410,  DOI:10.1016/j.matpr.2020.07.380.
277. A. R. Rozyanty, S. F. Zhafer, Z. Shayfull, I. Nainggolan, L. Musa and L. T. Zheing, Effect of water and mechanical retting process on mechanical and physical properties of kenaf bast fiber reinforced unsaturated polyester composites, Compos. Struct., 2021, 257, 113384,  DOI:10.1016/j.compstruct.2020.113384.
278. L. Zamora-Mendoza, F. Gushque, S. Yanez, N. Jara, J. F. Álvarez-Barreto, C. Zamora-Ledezma, S. A. Dahoumane and F. Alexis, Plant Fibers as Composite Reinforcements for Biomedical Applications, Bioengineering, 2023, 10, 804,  DOI:10.3390/bioengineering10070804.
279. A. Bernava, M. Manins and S. Kukle, Natural Fibers Woven Structures for Composites Reinforcements, J. Biobased Mater. Bioenergy, 2012, 6, 449–455,  DOI:10.1166/jbmb.2012.1247.
280. B. Karaçor, M. Özcanlı and H. Serin, The influence of hybridization and different manufacturing methods on the mechanical properties of the composites reinforced with basalt, jute, and flax fibers, Iran. Polym. J., 2024, 33, 289–304,  DOI:10.1007/s13726-023-01255-9.
281. K. Halashi, E. Taban, P. Soltani, S. Amininasab, E. Samaei, D. N. Moghadam and A. Khavanin, Acoustic and thermal performance of luffa fiber panels for sustainable building applications, Build. Environ., 2024, 247, 111051,  DOI:10.1016/j.buildenv.2023.111051.
282. J. Knapczyk-Korczak, P. K. Szewczyk, K. Berniak, M. M. Marzec, M. Frąc, W. Pichór and U. Stachewicz, Flexible and Thermally Insulating Porous Materials Utilizing Hollow Double-Shell Polymer Fibers, Adv. Sci., 2024, 11(36), 2404154,  DOI:10.1002/advs.202404154.
283. X. Liu, X. Yan, L. Li and H. Zhang, Sound-Absorption Properties of Kapok Fiber Nonwoven Fabrics at Low Frequency, J. Nat. Fibers, 2015, 12, 311–322,  DOI:10.1080/15440478.2014.919891.
284. H. Wang, Dinesh and J. Kim, Development of lightweight, high-strength, and highly porous ligno-nanocellulosic foam with excellent antioxidant and insulation properties, Carbohydr. Polym., 2024, 326(2024), 121616,  DOI:10.1016/j.carbpol.2023.121616.
285. L. Bravo-Moncayo, M. Argotti-Gómez, O. Jara, V. Puyana-Romero, G. Ciaburro and V. H. Guerrero, Thermo-Acoustic Properties of Four Natural Fibers, Musa textilis, Furcraea andina, Cocos nucifera, and Schoenoplectus californicus, for Building Applications, Buildings, 2024, 14, 2265,  DOI:10.3390/buildings14082265.
286. M. Fattahi, E. Taban, P. Soltani, U. Berardi, A. Khavanin and V. Zaroushani, Waste corn husk fibers for sound absorption and thermal insulation applications: A step towards sustainable buildings, J. Build. Eng., 2023, 77, 107468,  DOI:10.1016/j.jobe.2023.107468.
287. Q. Tang, M. Zou, S. Wang, L. Fang and W. Guo, Processing composites reinforced with wood fibers into an ultra-strong structural materials, Polym. Compos., 2021, 42, 2872–2881,  DOI:10.1002/pc.26021.
288. O. Hamdaoui, L. Ibos, A. Mazioud, M. Safi and O. Limam, Thermophysical characterization of Posidonia Oceanica marine fibers intended to be used as an insulation material in Mediterranean buildings, Constr. Build. Mater., 2018, 180, 68–76,  DOI:10.1016/j.conbuildmat.2018.05.195.
289. E. Dieckmann, R. Onsiong, B. Nagy, L. Sheldrick and C. Cheeseman, Valorization of Waste Feathers in the Production of New Thermal Insulation Materials, Waste Biomass Valoriz., 2021, 12, 1119–1131,  DOI:10.1007/s12649-020-01007-3.
290. S. Canbolat, D. Kut and H. Dayioglu, Investigation of pumice stone powder coating of multilayer surfaces in relation to acoustic and thermal insulation, J. Ind. Text., 2015, 44, 639–661,  DOI:10.1177/1528083713516665.
291. M. Zoccola, P. Bhavsar, A. Anceschi and A. Patrucco, Analytical Methods for the Identification and Quantitative Determination of Wool and Fine Animal Fibers: A Review, Fibers, 2023, 11, 67,  DOI:10.3390/fib11080067.
292. Y. Qian, C. Wang, Y. Liu, B. Shi, J. Zhang, Y. Wei and G. Chen, Effects of plant source selection and chemi-mechanical treatment on the fiber microstructures and mechanical behaviors of nanocellulose films, Wood Sci. Technol., 2025, 59, 7,  DOI:10.1007/s00226-024-01613-7.
293. C. L. Luchese, J. B. Engel and I. C. Tessaro, A Review on the Mercerization of Natural Fibers: Parameters and Effects, Korean J. Chem. Eng., 2024, 41, 571–587,  DOI:10.1007/s11814-024-00112-6.
294. D. Satheeshkumar, K. Saravanan and C. Prakash, A Study on the Moisture Management Properties of Banana/Bamboo Blended Fabrics, Fibers Polym., 2024, 25, 4469–4478,  DOI:10.1007/s12221-024-00728-9.
295. N. M. Nurazzi, M. R. M. Asyraf, M. Rayung, M. N. F. Norrrahim, S. S. Shazleen, M. S. A. Rani, A. R. Shafi, H. A. Aisyah, M. H. M. Radzi, F. A. Sabaruddin, R. A. Ilyas, E. S. Zainudin and K. Abdan, Thermogravimetric Analysis Properties of Cellulosic Natural Fiber Polymer Composites: A Review on Influence of Chemical Treatments, Polymers, 2021, 13, 2710,  DOI:10.3390/polym13162710.
296. R. Zhou, C. G. Li and M. X. Yang, Comparative Study on Structural Performance of Several New Regenerated Cellulose Fibers, Adv. Mater. Res., 2012, 573–574, 174–180,  DOI:10.4028/www.scientific.net/AMR.573-574.174.
297. M. T. Riaz, M. I. Khan, K. Shaker, Y. Nawab and M. Umair, Effect of Cellulosic Material and Weave Design on Comfort Performance of Woven Fabrics, J. Nat. Fibers, 2023, 20(1), 2163030,  DOI:10.1080/15440478.2022.2163030.
298. P. Miśkiewicz and M. Tokarska, Experimental Research on Basalt Fabric-Based Composites for Protection Against Contact Heat, J. Nat. Fibers, 2024, 21(1), 2418356,  DOI:10.1080/15440478.2024.2418356.
299. K. Yu, X. Shang, X. Zhao, L. Fu, X. Zuo and H. Yang, High frictional stability of braking material reinforced by Basalt fibers, Tribol. Int., 2023, 178, 108048,  DOI:10.1016/j.triboint.2022.108048.
300. P. Miśkiewicz and M. Tokarska, Shaping of thermal protective properties of basalt fabric-based composites by direct surface modification using magnetron sputtering technique, Autex Res. J., 2024, 24(1), 20230029,  DOI:10.1515/aut-2023-0029.
301. C. Ling, L. Guo and Z. Wang, A review on the state of flame-retardant cotton fabric: Mechanisms and applications, Ind. Crops Prod., 2023, 194, 116264,  DOI:10.1016/j.indcrop.2023.116264.
302. T.-C. Wang, M.-H. Jia, N.-T. Xu, W. Hu, Z. Jiang, B. Zhao, Y.-P. Ni and Z.-B. Shao, Facile fabrication of adenosine triphosphate/chitosan/polyethyleneimine coating for high flame-retardant lyocell fabrics with outstanding antibacteria, Int. J. Biol. Macromol., 2024, 260, 129599,  DOI:10.1016/j.ijbiomac.2024.129599.
303. G. Y. Romero-Zúñiga, P. González-Morones, S. Sánchez-Valdés, R. Yáñez-Macías, I. Sifuentes-Nieves, Z. García-Hernández and E. Hernández-Hernández, Microwave Radiation as Alternative to Modify Natural Fibers: Recent Trends and Opportunities – A Review, J. Nat. Fibers, 2022, 19, 7594–7610,  DOI:10.1080/15440478.2021.1952140.
304. M. Adam Bukhori Hamidon, R. Hussin, Z. Harun, M. Z. Yunos, A. R. Ainuddin, S. M. Rahim and N. Hamidon, Characterization of Kapok (Ceiba pentandra (L.) Gaertn.) and Its Reusability in Oil Sorption, Int. J. Nanoelectron. Mater., 2024, 17, 53–59,  DOI:10.58915/ijneam.v17iDecember.1607.
305. I. M. C. Silvino, B. S. Alves, E. J. Fonseca, V. B. Bernardo, C. L. P. S. Zanta, J. Tonholo, L. F. A. M. Oliveira, J. L. S. Duarte and L. M. T. M. Oliveira, Highly Efficient Bio-Based Composites from Natural Fibers for Fauna Protection and Oil Spill Remediation, Environ. Process., 2025, 12, 27,  DOI:10.1007/s40710-025-00771-5.
306. A. Farooq, L. Ying, H. Yang, B. Sarkodie, Y. Ding, M. Zhu, B. Susu, C. Hu, M. Tian and Z. Wang, Continuous oil–water separation by utilizing novel natural hollow fibers: evaluation and potential applications, Cellulose, 2024, 31, 3029–3051,  DOI:10.1007/s10570-024-05809-9.
307. A. Zarehshi and M. Aghajani, A review of plant fibers and their sorption property for wastewater treatment and water filter production, Discover Environ., 2025, 3, 243,  DOI:10.1007/s44274-025-00455-9.
308. W. Shi, Z. Zhao, A. Jiang, Y. Ma, Y. Yan, B. Yang and B. Chang, Ball-flower-like hierarchically porous carbons via a “work-in-tandem” strategy for effective energy storage and CO2 capture, J. Energy Storage, 2024, 84, 110636,  DOI:10.1016/j.est.2024.110636.
309. B. Dong, P. Yao, F. Xie, H. Yang, R. Arenal and W. Li, Kapok/regenerated cellulose based carbon aerogel prepared at a low-temperature carbonization for oil/water separation, Ind. Crops Prod., 2024, 222, 119743,  DOI:10.1016/j.indcrop.2024.119743.
310. A. Majavu, P. Moleko-Boyce, C. B. Moyo and Z. R. Tshentu, Selective diammonium reagents hosted on nanofibers for recovery of iridium from rhodium: Theoretical and experimental studies, Sep. Purif. Technol., 2021, 257, 117895,  DOI:10.1016/j.seppur.2020.117895.
311. E. Virga, K. Žvab and W. M. de Vos, Fouling of nanofiltration membranes based on polyelectrolyte multilayers: The effect of a zwitterionic final layer, J. Membr. Sci., 2021, 620, 118793,  DOI:10.1016/j.memsci.2020.118793.
312. S. Gbogbo, D. Narh, Y. K. Adofo, B. Mensah, B. Agyei-Tuffour and E. Nyankson, Effects of modified sugar cane and plantain pseudo-stem fibers for oil spill remediation, Cogent Eng., 2024, 11(1), 2342442,  DOI:10.1080/23311916.2024.2342442.
313. V. Antonov, J. Marek, M. Bjelkova, P. Smirous and H. Fischer, Easily available enzymes as natural retting agents, Biotechnol. J., 2007, 2, 342–346,  DOI:10.1002/biot.200600110.
314. P. M. Tahir, A. B. Ahmed, S. O. A. SaifulAzry and Z. Ahmed, Retting process of some bast plant fibers and its effect on fibre quality: A review, Bioresources, 2011, 6, 5260–5281,  DOI:10.15376/biores.6.4.5260-5281.
315. L. Bacci, S. Di Lonardo, L. Albanese, G. Mastromei and B. Perito, Effect of different extraction methods on fiber quality of nettle (Urtica dioica L.), Text. Res. J., 2011, 81, 827–837,  DOI:10.1177/0040517510391698.
316. Z. Jankauskienė, B. Butkutė, E. Gruzdevienė, J. Cesevičienė and A. L. Fernando, Chemical composition and physical properties of dew- and water-retted hemp fibers, Ind. Crops Prod., 2015, 75, 206–211,  DOI:10.1016/j.indcrop.2015.06.044.
317. S. Amaducci and H. Gusovius, Hemp – Cultivation, Extraction and Processing, in. Industrial Applications of Natural Fibres, Wiley, 2010, pp. 109–134,  DOI:10.1002/9780470660324.ch5.
318. A. Ribeiro, P. Pochart, A. Day, S. Mennuni, P. Bono, J.-L. Baret, J.-L. Spadoni and I. Mangin, Microbial diversity observed during hemp retting, Appl. Microbiol. Biotechnol., 2015, 99, 4471–4484,  DOI:10.1007/s00253-014-6356-5.
319. H. M. G. van der Werf and L. Turunen, The environmental impacts of the production of hemp and flax textile yarn, Ind. Crops Prod., 2008, 27, 1–10,  DOI:10.1016/j.indcrop.2007.05.003.
320. V. S. Sreenivasan, S. Somasundaram, D. Ravindran, V. Manikandan and R. Narayanasamy, Microstructural, physico-chemical and mechanical characterisation of Sansevieria cylindrica fibres – An exploratory investigation, Mater. Des., 2011, 32, 453–461,  DOI:10.1016/j.matdes.2010.06.004.
321. K. Shaker, R. M. Waseem Ullah Khan, M. Jabbar, M. Umair, A. Tariq, M. Kashif and Y. Nawab, Extraction and characterization of novel fibers from Vernonia elaeagnifolia as a potential textile fiber, Ind. Crops Prod., 2020, 152, 112518,  DOI:10.1016/j.indcrop.2020.112518.
322. S. K. Ramamoorthy, M. Skrifvars and A. Persson, A Review of Natural Fibers Used in Biocomposites: Plant, Animal and Regenerated Cellulose Fibers, Polym. Rev., 2015, 55, 107–162,  DOI:10.1080/15583724.2014.971124.
323. L. T. Drzal, A. K. Mohanty, M. Misra, Natural Fibers, Biopolymers, and Biocomposites, CRC Press, 2005, p. 896, DOI:  DOI:10.1201/9780203508206.
324. M. M. A. Nassar, K. I. Alzebdeh, N. Al-Hinai and T. Pervez, A New Multistep Chemical Treatment Method for High Performance Natural Fibers Extraction, J. Nat. Fibers, 2023, 20(1), 2150922,  DOI:10.1080/15440478.2022.2150922.
325. M. Balasubramanian, R. Saravanan and S. T, Exploring natural plant fiber choices and treatment methods for contemporary composites: A comprehensive review, Results Eng., 2024, 24, 103270,  DOI:10.1016/j.rineng.2024.103270.
326. S. Garriba, H. S. Jailani, C. K. A. Pandian and P. Diwahar, Effect of water retting on the physical and mechanical properties of lignocellulosic fiber from Mariscus ligularis plant, Int. J. Biol. Macromol., 2025, 288, 138718,  DOI:10.1016/j.ijbiomac.2024.138718.
327. D. E. Akin, R. B. Dodd, W. Perkins, G. Henriksson and K.-E. L. Eriksson, Spray Enzymatic Retting: A New Method for Processing Flax Fibers, Text. Res. J., 2000, 70, 486–494,  DOI:10.1177/004051750007000604.
328. A. K. Ghorai and A. K. Chakraborty, Sustainable In-situ Jute Retting Technology in Low Volume Water using Native Microbial Culture to Improve Fibre Quality and Retting Waste Management, Int. J. Curr. Microbiol. Appl. Sci., 2020, 9, 1080–1099,  DOI:10.20546/ijcmas.2020.911.126.
329. M. M. Hossain, S. Siddiquee and V. Kumar, Water Sources Derived Bio Retting Effect on Kenaf Fiber Compositions, J. Nat. Fibers, 2022, 19, 9396–9409,  DOI:10.1080/15440478.2021.1982829.
330. J. Harsányi, M. Poraj-Kobielska, H. Wedwitschka, M. Tirsch and J. Kretzschmar, Controlled anaerobic water retting of flax as part of an innovative biorefinery process, Biomass Convers. Biorefinery, 2025, 15, 16499–16510,  DOI:10.1007/s13399-024-06452-x.
331. Z. A. PM Tahir, A. B. Ahmed and S. O. A. SaifulAzry, Retting process of some bast plant fibres and its effect on fibre quality: a review, BioResources, 2011, 6, 5260–5281 . https://bioresources.cnr.ncsu.edu/BioRes_06/BioRes_06_Unsecured/BioRes_06_4_5260_Paridah_ASZ_Retting_Bast_Fiber_Quality_Review_1312.pdf.
332. E. Bou Orm, S. Mukherjee, E. Rifa, A. Créach, S. Grec, S. Bayle, J. Benezet, A. Bergeret and L. Malhautier, Enhancing Biodiversity-Function Relationships in Field Retting: Towards Key Microbial Indicators for Retting Control, Environ. Microbiol. Rep., 2025, 17(3), e70102,  DOI:10.1111/1758-2229.70102.
333. J. A. Foulk, D. E. Akin and R. B. Dodd, Processing techniques for improving enzyme-retting of flax, Ind. Crops Prod., 2001, 13, 239–248,  DOI:10.1016/S0926-6690(00)00081-9.
334. D. E. Akin, J. A. Foulk and R. B. Dodd, Influence on Flax Fibers of Components in Enzyme Retting Formulations, Text. Res. J., 2002, 72, 510–514,  DOI:10.1177/004051750207200608.
335. D. Yadav, S. Yadav, R. Dwivedi, G. Anand and P. K. Yadav, Potential of Microbial Enzymes in Retting of Natural Fibers: A Review, Curr. Biochem. Eng., 2016, 3, 89–99,  DOI:10.2174/221271190302160607151925.
336. V. Ventorino, F. E. Chouyia, I. Romano, M. Mori and O. Pepe, Water retting process with hemp pre-treatment: effect on the enzymatic activities and microbial populations dynamic, Appl. Microbiol. Biotechnol., 2024, 108, 464,  DOI:10.1007/s00253-024-13300-5.
337. L. Huang, J. Peng, M. Tan, J. Fang and K. Li, An efficient preparation process of sisal fibers via the specialized retting microorganisms: Based on the ideal combination of degumming-related enzymes for the effective removal of non-cellulosic macromolecules, Int. J. Biol. Macromol., 2024, 274, 133416,  DOI:10.1016/j.ijbiomac.2024.133416.
338. G. R. Nair, Role of Microwave Pre Treatment in the Extraction of High Quality Natural Fibers, J. Text. Eng. Fashion Technol., 2017, 2(10), 15406,  DOI:10.15406/jteft.2017.02.00053.
339. P. Ruan, J. Du, Y. Gariepy and V. Raghavan, Characterization of radio frequency assisted water retting and flax fibers obtained, Ind. Crops Prod., 2015, 69, 228–237,  DOI:10.1016/j.indcrop.2015.02.009.
340. D. Zhao, H. Ji, R. Du, Q. Wang, W. Ping and J. Ge, Optimization of process conditions for microwave-assisted flax water retting by response surface methodology and evaluation of its fiber properties, Bioresources, 2020, 15, 5859–5870,  DOI:10.15376/biores.15.3.5859-5870.
341. A. Bismarck, I. Aranberri-Askargorta, J. Springer, T. Lampke, B. Wielage, A. Stamboulis, I. Shenderovich and H. Limbach, Surface characterization of flax, hemp and cellulose fibers; Surface properties and the water uptake behavior, Polym. Compos., 2002, 23, 872–894,  DOI:10.1002/pc.10485.
342. G. T. Pott, Natural Fibers with Low Moisture Sensitivity, in. Natural Fibers, Plastics and Composites, Springer US, Boston, MA, 2004, pp. 105–122,  DOI:10.1007/978-1-4419-9050-1_8.
343. M. Mohammed, R. Rahman, A. M. Mohammed, T. Adam, B. O. Betar, A. F. Osman and O. S. Dahham, Surface treatment to improve water repellence and compatibility of natural fiber with polymer matrix: Recent advancement, Polym. Test., 2022, 115, 107707,  DOI:10.1016/j.polymertesting.2022.107707.
344. M. Easson, B. Condon, A. Villalpando and S. Chang, The application of ultrasound and enzymes in textile processing of greige cotton, Ultrasonics, 2018, 84, 223–233,  DOI:10.1016/j.ultras.2017.11.007.
345. P. Lyu, Y. Zhang, X. Wang and C. Hurren, Degumming methods for bast fibers—A mini review, Ind. Crops Prod., 2021, 174, 114158,  DOI:10.1016/j.indcrop.2021.114158.
346. W. Konczewicz, M. Zimniewska and M. A. Valera, The selection of a retting method for the extraction of bast fibers as response to challenges in composite reinforcement, Text. Res. J., 2018, 88, 2104–2119,  DOI:10.1177/0040517517716902.
347. L. Sisti, G. Totaro, M. Vannini and A. Celli, Retting Process as a Pretreatment of Natural Fibers for the Development of Polymer Composites, Chem. Mater. Sci., 2018, 97–135,  DOI:10.1007/978-3-319-68696-7_2.
348. K. Gandhi, S. Khan, M. Patrikar, A. Markad, N. Kumar, A. Choudhari, P. Sagar and S. Indurkar, Exposure risk and environmental impacts of glyphosate: Highlights on the toxicity of herbicide co-formulants, Environ. Challenges, 2021, 4, 100149,  DOI:10.1016/j.envc.2021.100149.
349. D. Ray, B. Sarkar, A. Rana and N. Bose, The mechanical properties of vinylester resin matrix composites reinforced with alkali-treated jute fibres, Composites, Part A, 2001, 32, 119–127,  DOI:10.1016/S1359-835X(00)00101-9.
350. L. Wang, K. Li, K. Copenhaver, S. Mackay, M. E. Lamm, X. Zhao, B. Dixon, J. Wang, Y. Han, D. Neivandt, D. A. Johnson, C. C. Walker, S. Ozcan and D. J. Gardner, Review on Nonconventional Fibrillation Methods of Producing Cellulose Nanofibrils and Their Applications, Biomacromolecules, 2021, 22, 4037–4059,  DOI:10.1021/acs.biomac.1c00640.
351. A. Ali, K. Shaker, Y. Nawab, M. Jabbar, T. Hussain, J. Militky and V. Baheti, Hydrophobic treatment of natural fibers and their composites—A review, J. Ind. Text., 2018, 47, 2153–2183,  DOI:10.1177/1528083716654468.
352. R. D. S. G. Campilho, Natural Fiber Composites, CRC Press, 2015,  DOI:10.1201/b19062.
353. A. I. S. Brígida, V. M. A. Calado, L. R. B. Gonçalves and M. A. Z. Coelho, Effect of chemical treatments on properties of green coconut fiber, Carbohydr. Polym., 2010, 79, 832–838,  DOI:10.1016/j.carbpol.2009.10.005.
354. S. H. Aziz and M. P. Ansell, The effect of alkalization and fibre alignment on the mechanical and thermal properties of kenaf and hemp bast fibre composites: Part 1 – polyester resin matrix, Compos. Sci. Technol., 2004, 64, 1219–1230,  DOI:10.1016/j.compscitech.2003.10.001.
355. D. Gunwant, Moisture resistance treatments of natural fiber-reinforced composites: a review, Compos. Interfaces, 2024, 31, 979–1047,  DOI:10.1080/09276440.2024.2303543.
356. M. Petrič, Influence of Silicon-Containing Compounds on Adhesives for and Adhesion to Wood and Lignocellulosic Materials: A Critical Review, in. Progress in Adhesion and Adhesives, Wiley, 2019, pp. 25–76,  DOI:10.1002/9781119625322.ch2.
357. K. Olonisakin, M. Fan, Z. Xin-Xiang, L. Ran, W. Lin, W. Zhang and Y. Wenbin, Key Improvements in Interfacial Adhesion and Dispersion of Fibers/Fillers in Polymer Matrix Composites; Focus on PLA Matrix Composites, Compos. Interfaces, 2022, 29, 1071–1120,  DOI:10.1080/09276440.2021.1878441.
358. M. Mohammadi, M. R. Ishak and M. T. H. Sultan, Exploring Chemical and Physical Advancements in Surface Modification Techniques of Natural Fiber Reinforced Composite: A Comprehensive Review, J. Nat. Fibers, 2024, 21(1), 2408633,  DOI:10.1080/15440478.2024.2408633.
359. Y. Wang, X. Wang, Y. Xie and K. Zhang, Functional nanomaterials through esterification of cellulose: a review of chemistry and application, Cellulose, 2018, 25, 3703–3731,  DOI:10.1007/s10570-018-1830-3.
360. V. Tserki, N. E. Zafeiropoulos, F. Simon and C. Panayiotou, A study of the effect of acetylation and propionylation surface treatments on natural fibres, Composites, Part A, 2005, 36, 1110–1118,  DOI:10.1016/j.compositesa.2005.01.004.
361. N. E. Zafeiropoulos and C. A. Baillie, A study of the effect of surface treatments on the tensile strength of flax fibres: Part II. Application of Weibull statistics, Composites, Part A, 2007, 38, 629–638,  DOI:10.1016/j.compositesa.2006.02.005.
362. A. K. Bledzki, A. A. Mamun, M. Lucka-Gabor and V. S. Gutowski, The effects of acetylation on properties of flax fibre and its polypropylene composites, Express Polym. Lett., 2008, 2, 413–422,  DOI:10.3144/expresspolymlett.2008.50.
363. M. Mohammed, M. Rasidi, A. Mohammed, R. Rahman, A. Osman, T. Adam, B. Betar and O. Dahham, Interfacial bonding mechanisms of natural fibre-matrix composites: An overview, Bioresources, 2022, 17(4), 7031,  DOI:10.15376/biores.17.4.Mohammed.
364. A. More, T. Elder and Z. Jiang, A review of lignin hydrogen peroxide oxidation chemistry with emphasis on aromatic aldehydes and acids, Holzforschung, 2021, 75, 806–823,  DOI:10.1515/hf-2020-0165.
365. B. Wang, S. Panigrahi, L. Tabil and W. Crerar, Pre-treatment of Flax Fibers for use in Rotationally Molded Biocomposites, J. Reinf. Plast. Compos., 2007, 26, 447–463,  DOI:10.1177/0731684406072526.
366. M. S. Sreekala, M. G. Kumaran, S. Joseph, M. Jacob and S. Thomas, Oil Palm Fibre Reinforced Phenol Formaldehyde Composites: Influence of Fibre Surface Modifications on the Mechanical Performance, Appl. Compos. Mater., 2000, 7, 295–329,  DOI:10.1023/A:1026534006291.
367. K. Pickering, Properties and Performance of Natural-Fibre Composites, Woodhead Publishing, 2008.
368. M. Ragoubi, D. Bienaimé, S. Molina, B. George and A. Merlin, Impact of corona treated hemp fibres onto mechanical properties of polypropylene composites made thereof, Ind. Crops Prod., 2010, 31, 344–349,  DOI:10.1016/j.indcrop.2009.12.004.
369. M. Ragoubi, B. George, S. Molina, D. Bienaimé, A. Merlin, J.-M. Hiver and A. Dahoun, Effect of corona discharge treatment on mechanical and thermal properties of composites based on miscanthus fibres and polylactic acid or polypropylene matrix, Composites, Part A, 2012, 43, 675–685,  DOI:10.1016/j.compositesa.2011.12.025.
370. B. Koohestani, A. K. Darban, P. Mokhtari, E. Yilmaz and E. Darezereshki, Comparison of different natural fiber treatments: a literature review, Int. J. Sci. Environ. Technol., 2019, 16, 629–642,  DOI:10.1007/s13762-018-1890-9.
371. S. M.R., S. Siengchin, J. Parameswaranpillai, M. Jawaid, C. I. Pruncu and A. Khan, A comprehensive review of techniques for natural fibers as reinforcement in composites: Preparation, processing and characterization, Carbohydr. Polym., 2019, 207(2019), 108–121,  DOI:10.1016/j.carbpol.2018.11.083.
372. T. Townsend, World natural fibre production and employment, in. Handbook of Natural Fibres, Elsevier, 2020, pp. 15–36,  DOI:10.1016/B978-0-12-818398-4.00002-5.
373. A. D. Mayana, From Waste to Inclusive Green Growth: Assessing the Socio-Economic and Environmental Impact of Textile recycling―A Case Study of Indonesia, Lund University Centre for Sustainability Studies, 2025. https://lup.lub.lu.se/student-papers/search/publication/9199547.
374. A. P. Boban, N. Kumar and D. K. Mishra, A Review on Pineapple and Banana Natural Fiber Composite, Engineering, 2025, 25–38,  DOI:10.1007/978-981-97-7114-1_3.
375. A. Karimah, M. R. Ridho, S. S. Munawar, Ismadi, Y. Amin, R. Damayanti, M. A. R. Lubis, A. P. Wulandari, Nurindah, A. H. Iswanto, A. Fudholi, M. Asrofi, E. Saedah, N. H. Sari, B. R. Pratama, W. Fatriasari, D. S. Nawawi, S. M. Rangappa and S. Siengchin, A Comprehensive Review on Natural Fibers: Technological and Socio-Economical Aspects, Polymers, 2021, 13(24), 4280,  DOI:10.3390/polym13244280.
376. S. A. Miller, Natural fiber textile reinforced bio-based composites: Mechanical properties, creep, and environmental impacts, J. Cleaner Prod., 2018, 198, 612–623,  DOI:10.1016/j.jclepro.2018.07.038.
377. L. Oliveira Duarte, L. Kohan, L. Pinheiro, H. Fonseca Filho and J. Baruque-Ramos, Textile natural fibers production regarding the agroforestry approach, SN Appl. Sci., 2019, 1, 914,  DOI:10.1007/s42452-019-0937-y.
378. V. Shanmugam, R. A. Mensah, M. Försth, G. Sas, Á. Restás, C. Addy, Q. Xu, L. Jiang, R. E. Neisiany, S. Singha, G. George, T. Jose E, F. Berto, M. S. Hedenqvist, O. Das and S. Ramakrishna, Circular economy in biocomposite development: State-of-the-art, challenges and emerging trends, Compos., Part C: Open Access, 2021, 5, 100138,  DOI:10.1016/j.jcomc.2021.100138.
379. F. Allafi, M. S. Hossain, J. Lalung, M. Shaah, A. Salehabadi, M. I. Ahmad and A. Shadi, Advancements in Applications of Natural Wool Fiber: Review, J. Nat. Fibers, 2022, 19, 497–512,  DOI:10.1080/15440478.2020.1745128.
380. C. F. Justice, Slashing methane emissions is the fastest way fashion brands can help to reduce global temperatures, Collective Fashion Justice, 2025 , https://www.collectivefashionjustice.org/methane-reduction.
381. A. Karimah, M. R. Ridho, S. S. Munawar, D. S. Adi, Ismadi, R. Damayanti, B. Subiyanto, W. Fatriasari and A. Fudholi, A review on natural fibers for development of eco-friendly bio-composite: characteristics, and utilizations, J. Mater. Res. Technol., 2021, 13(2021), 2442–2458,  DOI:10.1016/j.jmrt.2021.06.014.
382. V. Khandegar and A. K. Saroha, Electrocoagulation for the treatment of textile industry effluent – A review, J. Environ. Manage., 2013, 128, 949–963,  DOI:10.1016/j.jenvman.2013.06.043.
383. S. G. Wiedemann, S. J. Clarke, Q. V. Nguyen, Z. X. Cheah and A. T. Simmons, Strategies to reduce environmental impacts from textiles: Extending clothing wear life compared to fibre displacement assessed using consequential LCA, Resour., Conserv. Recycl., 2023, 198, 107119,  DOI:10.1016/j.resconrec.2023.107119.
384. D. Mota-Rojas, C. G. Titto, A. de Mira Geraldo, J. Martínez-Burnes, J. Gómez, I. Hernández-Ávalos, A. Casas, A. Domínguez, N. José, A. Bertoni, B. Reyes and A. M. F. Pereira, Efficacy and Function of Feathers, Hair, and Glabrous Skin in the Thermoregulation Strategies of Domestic Animals, Animals, 2021, 11, 3472,  DOI:10.3390/ani11123472.
385. R. S. Abolore, S. Jaiswal and A. K. Jaiswal, Green and sustainable pretreatment methods for cellulose extraction from lignocellulosic biomass and its applications: A review, Carbohydr. Polym. Technol. Appl., 2024, 7, 100396,  DOI:10.1016/j.carpta.2023.100396.
386. I. Elfaleh, F. Abbassi, M. Habibi, F. Ahmad, M. Guedri, M. Nasri and C. Garnier, A comprehensive review of natural fibers and their composites: An eco-friendly alternative to conventional materials, Results Eng., 2023, 19, 101271,  DOI:10.1016/j.rineng.2023.101271.
387. M. Ge, F. Chen, C. Chen, H. Cong, Z. Dong and P. Ma, Large-scale production of a “skin-like” self-pumping fabric for personal sweat management, Chem. Eng. J., 2024, 495, 153098,  DOI:10.1016/j.cej.2024.153098.
388. C. L. França, G. Broman, K.-H. Robèrt, G. Basile and L. Trygg, An approach to business model innovation and design for strategic sustainable development, J. Cleaner Prod., 2017, 140, 155–166,  DOI:10.1016/j.jclepro.2016.06.124.

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