Optical and flexible α-chitin nanofibers reinforced poly(vinyl alcohol) (PVA) composite film: Fabrication and property

In this study, α-chitin nanofibers (CNFs)–poly(vinyl alcohol) (PVA) composite films were fabricated to evaluate the compatibility and reinforcement effect of CNFs to PVA. CNFs were disintegrated by one-pass grinding and 40-min ultrasonication. The diameter of most of CNFs ranged from 30 nm to 50 nm. The CNFs–PVA composite films were made by immersing CNFs sheet into PVA solution. FTIR and XRD analysis revealed that there are strong interaction and good compatibility between CNFs and PVA molecular. In comparison with the neat PVA film, the light transmittance of the composite film slightly decreased from 92% to 86%. The coefficient of thermal expansion dramatically decreased from 123.62 ppm K−1 to 25.09 ppm K−1. The tensile strength and Young’s modulus were high to 127 MPa and 5.70 GPa, which were about 100% and 140% larger than those of the PVA film. The elongation at break point of the composite film decreased from 20.70% to 4.40%.