The degradation investigation of biodegradable PLA/PBAT blend: Thermal stability, mechanical properties and PALS analysis

Abstract Polymer blends of polylactide (PLA) with poly (butylene adipate-co-terephthalate) (PBAT) to improve properties of PLA has been researched widely. But very few researches focus on the degradation of the blend, which is very important for biodegradable material. Herein, PLA and PBAT blends are prepared through solution casting, and the impact of degradation on thermal and mechanical properties of the blend are analyzed. Young’s modulus of the blend tends to keep steady, while tensile strain decreases drastically with degradation going on. Degradation also leads to poor thermal stability of the blend. Positron annihilation lifetime spectroscopy (PALS) is applied for the first time to investigate degradation process of PLA/PBAT blend, it shows that free volume holes have an increase in quantity and a decrease in size at the beginning of degradation, then show a decrease in quantity and an increase in size as the degradation going on. These findings give fundamental information for PLA/PBAT degradation process and the impact on properties, which helps the further development of PLA blend modification.