Recovery of cellulose nanocrystal from mixed office wastepaper and the development of bio-based coating matrixes with enhanced water, gas, oil, and grease resistances for packaging

Abstract

This study on sustainable nanocellulose modifications for various packaging applications is driven by the global social awareness and growing demand for bioproducts to reduce the use of single-use plastics. Mixed office waste (MOW) was used as the raw material to extract cellulose nanocrystals (CNCs) via the acid hydrolysis method. The average length and diameter of the CNCs were approximately 104.08 ± 0.1 nm and 9.49 ± 0.3 nm, respectively. The crystallinity index was 87%, as confirmed using transmission electron microscopy and X-ray diffraction analysis. Coating solutions of varying concentrations were prepared by mixing CNCs with collagen hydrolysate and glycerin, and the coatings were applied to the surface of uncoated paper via a rod coating process. FTIR spectra confirmed the presence of CNCs in the coated paper. High-resolution FE-SEM images provided detailed information on the surface morphology of the coated papers. The barrier and mechanical performances of the coated paper were evaluated using the oil and grease resistance KIT, hot oil, water vapor permeability, air permeability, water contact angle, tensile index, burst index, percentage of elongation, and fold tests. All the coated paper samples passed the hot oil test and exhibited the highest KIT rating. The water vapor and air resistance values of the coated paper samples increased 14 times and 250 times, respectively, compared with the uncoated paper samples. The water contact angle of the coated paper samples increased to 99.40° from 60.13°, and the surface roughness decreased from 2.37 μm to 0.85 μm. The presence of coating also increased the tensile and burst indices by 5.28 times and 1.79 times, respectively, compared with the uncoated paper samples. No cytotoxic effects were found in the optimized coated paper, and all the samples were fully degraded within 49 days, as confirmed using the soil biodegradability test. Therefore, the coated paper can be a potential alternative to existing single-use plastics for packaging materials.