Abstract:

This study developed a novel anaerobic biodegradable polypropylene （PP） film by incorporating ethyl acrylate⁃grafted chitin via a three⁃layer cast co⁃extrusion process. The successful grafting of ethyl acrylate onto chitin， confirmed by nuclear magnetic resonance， Fourier⁃transform infrared， and Raman spectroscopy， significantly enhanced its thermal stability， increasing the decomposition temperature to 340 °C. The modified chitin was compounded into a masterbatch with PP. The incorporation of 3 % monoglycerides as a compatibilizer improved the fluidity and dispersion of the masterbatch containing 10 % chitin. In the final extruded films， modified chitin content at or below 1.5 % acted as a heterogeneous nucleating agent， increasing the crystallinity， melting point， and crystallization rate of PP. At a 2 % loading， the film exhibited optimal tensile strength of 12.8 MPa， although elongation at break decreased. This formulation also demonstrated excellent optical properties， with a light transmittance of 87.6 % and haze of 4.6 %， surpassing the clarity requirements of the national BOPP film standard. Crucially， anaerobic composting tests revealed that films with 1.5 % modified chitin achieved an average biodegradation rate of 9.19 % over 56 days， confirming the effectiveness of this approach in enhancing the anaerobic biodegradability of PP films without severely compromising their mechanical and optical properties.

Key words: chitin, graft modification, polypropylene film, anaerobic biodegradation, three?layer cast co?extrusion