Preparation and characterization of compatibilized and toughened polylactic acid/cellulose acetate films by long‐chain hyperbranched polymers

Abstract A type of long‐chain hyperbranched polymers (LCHBPs) was prepared by grafting hydroxyl‐terminated flexible long chain onto hyperbranched polymers (HBPs). The structure of LCHBPs was confirmed by Fourier transform infrared (FT‐IR) and nuclear magnetic resonance ( 1 H‐NMR) analysis. It was then used as the modifier for toughening and compatibilizing the polylactic acid (PLA)/cellulose acetate (CA) blends. Upon the addition of LCHBPs, the compatibility between PLA and CA was improved, the dispersion of CA particles in PLA matrix was more uniform, and the brittle‐ductile tear transition of the PLA/CA blends was occurred. The crystallization of PLA was promoted by the addition of LCHBPs. By adding LCHBPs, glass transition temperature and cold crystallization temperature were reduced, the crystallizability was enhanced, and the crystallization temperature range was expanded. The thermal decomposition temperature of the PLA/CA was found increased with the addition of LCHBPs. When the content of LCHBPs was 1 phr, the elongation at break and the tear strength of the PLA/CA blends were increased by 484% and 38.24%, respectively. Meanwhile, the thermal stability and hydrophilic properties of the blend films were improved by adding LCHBPs.