High-Yield Cellulose Nanocrystals Based on Waste Cotton Fabrics and Its Reinforcement of PVA Composite Films

Abstract

The high-value transformation of cellulose-based waste cotton fabrics holds great significance for resolving the dilemmas faced by the textile industry. Cellulose nanocrystals (CNCs), emerging as novel high-value nanomaterials, possess substantial potential in reinforcement applications. This study aimed to explore two aspects: the production of CNCs from waste cotton fabrics and the reinforcement effect of CNCs in PVA composite films. The maximum yield of CNCs, reaching 88.3%, was achieved from cotton fabrics through treatment with 64% H₂SO₄ at 60 °C for 60 min. Under optimal conditions, the prepared rod-shaped CNCs, obtained using 56% and 64% H₂SO₄, had lengths of 203.5 ± 64.6 nm and 87.4 ± 23.3 nm, and diameters of 20.6 ± 6.8 nm and 16.1 ± 3.3 nm, respectively. Characterization results demonstrated that CNCs prepared under different conditions exhibited good crystalline structures and thermal stability. However, with an increase in sulfuric acid concentration, the T_onset and T_max of CNCs showed a decreasing trend. When 5% of the CNCs prepared with 56% and 64% H₂SO₄ was added to PVA, compared to neat PVA films, the PVA composite films showed improvements in tensile strength by 70.10% and 40.98%, and in elongation at break by 85.68% and 88.97%, respectively. This research offers an effective approach for the high-yield production of CNCs from waste cotton fabrics and their reinforcement applications in PVA composite films.