Multiple actions of poly(ethylene octene) grafted with glycidyl methacrylate on the performance of poly(lactic acid)

Poly(ethylene octene) grafted with glycidyl methacrylate (POE-g-GMA) was employed to improve the rheological and thermal properties, toughness, and foaming behaviors of poly(lactic acid) (PLA) through a chain extension effect. The dynamic rheological properties of PLA were improved significantly with increasing content of POE-g-GMA, due to the chain extension reaction between PLA and POE-g-GMA. As the content of POE-g-GMA increased, the cold crystallization temperature of PLA decreased by more than 10 °C and the crystallinity of PLA increased slightly from 1.2% to 4.7%, respectively. The impact strength of PLA with a POE-g-GMA content of 10 wt% increased by more than 4 times, compared with that of pure PLA. A sea-island structure could be observed in the PLA/POE-g-GMA blends and the distribution of POE-g-GMA was uniform. PLA foams with various POE-g-GMA contents were prepared in a stainless-steel autoclave using supercritical CO₂ as a physical blowing agent. The cellular morphology of PLA foam was obviously improved when the concentration of POE-g-GMA increased from 5 wt% to 10 wt%.