Reactive extrusion of biodegradable PGA/PBAT blends to enhance flexibility and gas barrier properties

Abstract

AbstractAmong commercial biodegradable polyesters, poly(glycolic acid) (PGA) has been rarely investigated for packaging applications, despite its unique advantages such as 100% compostability, high degree of crystallinity, high thermal stability and high gas barrier properties. The application of PGA has been limited by its mechanical brittleness, moisture sensitivity, and high melting temperature (~240°C), restricting its processing and applications for film packaging. In this study, PGA was modified by blending with poly (butylene adipate‐co‐terephthalate) (PBAT) via melt‐extrusion. A commercial terpolymer of ethylene, acrylic ester and glycidyl methacrylate (EMA‐GMA) was selected for compatibilization. The phase morphology, rheology, thermal, mechanical and gas barrier properties of the blends were investigated. With addition of 20 wt. % EMA‐GMA, the elongation of PGA/PBAT (50/50 wt. %) blends was improved from 10.7% to 145%, the oxygen permeability was reduced from 125 to 103 (cm3 mm)/(m2 24 h atm), and the water vapor barrier performance was improved by ~47%. The enhancement in ductility, oxygen and water vapor barrier properties of the flexible blends were ascribed to the interfacial bonding between PBAT and PGA enabled by EMA‐GMA. The compatibilized PGA/PBAT blends with high thermal stability up to 300°C are preferable for high temperature or hot food packaging.