Thermal-tenacity-enhanced and biodegradable textile sizes from cellulose nanocrystals reinforced soy protein for effective yarn coating

High-efficiency, biodegradable and easy-desized cellulose nanocrystals (CNC) modified soy protein sizing agents were prepared by incorporating CNC as protein molecular extenders, crosslinkers and reinforcements in soy protein sizes system for multifunctional yarn coating against film thermal-embrittlement and yarn abrasion during slashing. In this research, we found CNC could endow soy protein with unfolded and trimly arranged molecular structure as well as enhanced intermolecular slippage, especially under high temperature conditions. Thermal-tenacity (work of fracture) and tensile strength at constant temperature of the soy films were improved 731% and 93.9%, respectively, after being modified by CNC. Compared with poor biodegradable polyvinyl alcohol (PVA) sizes films, thermal tensile strength of 10CNC modified soy films was 118% higher. Regarding sizing performance, CNC reinforced soy sizes had 51.4% and 5.09% higher adhesion properties and 43.1% and 38.3% lower friction coefficient to both cotton yarn and viscose/polyester (65/35) yarns compared to the soy sizes. In addition, the CNC-soy sizes agents possessed excellent desizing performance and biodegradability, indicating the great potential as a substitute of petro-based PVA sizes. Successful utilization of CNC-soy sizes will lead to large-quantity applications of soy byproducts, impelling high value addition to agricultural byproducts and sustainability in textile industry.