Eco-friendly starch-nanocellulose bio-nanocomposite films with improved structure–property interactions

Abstract

The development of sustainable and biodegradable substitutes has increased due to growing environmental concerns surrounding petroleum-based polymers. Herein, starch-nanocellulose bio-nanocomposite films were fabricated and thoroughly characterized in order to assess the impact of nanocellulose fiber loading on their physicochemical, structural, thermal, optical, and mechanical properties. Using a straightforward solution-casting technique, sulfuric acid hydrolysis was used to remove nanocellulose from a filter paper and incorporate it into a thermoplastic starch matrix plasticized with glycerol. Water uptake, moisture absorption, and solubility analyses, tensile testing, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and UV-vis spectroscopy were used to make and evaluate composite films containing 0, 5, 10, and 20 weight percent nanocellulose. Results demonstrated that increasing the nanocellulose content substantially decreased water uptake and moisture absorption because of the reduced free volume and increased hydrogen bonding within the matrix. The use of nanocellulose enhanced film continuity and decreased cracking, as demonstrated by morphological observations. TGA showed increased thermal stability at larger nanocellulose loadings, while XRD examination showed a steady rise in crystallinity from 32% for clean starch to 60% for the 20-weight percent nanocellulose composite. Although elongation at break reduced as a result of higher stiffness, mechanical testing revealed significant increases in tensile strength and Young's modulus with increasing nanocellulose concentration. These results show that the starch-nanocellulose bio-nanocomposites have enhanced strength, thermal resistance, and barrier qualities, underscoring their great promise as environmentally benign materials for biodegradable packaging and associated uses.