The Ternary Blends of TPS/PBAT/PLA Films: A Study on the Morphological and Mechanical Properties

This study investigated the effect of polylactic acid (PLA) on the mechanical properties and biodegradability of a ternary blend comprising of thermoplastic starch (TPS), Polybutylene adipate terephthalate (PBAT) and PLA. The binary blend (TPS/PBAT) and ternary blend (TPS/PBAT/PLA) with various contents of PLA were prepared through a twin-screw compounding using an intensive mixing screw design. In order to observe the microstructure in blends, the SEM observation revealed the two types of morphology in the blends including (1) some TPS domain that still remained immiscible in all blends and (2) the partially compatible of binary and ternary blends. For the mechanical properties of the blends, the addition of the PLA component led to an improvement of the tensile strength and modulus. For the simple soil burial test, it found that binary film was fully disintegrated within one month, whereas the ternary blend films were also broken down but still remained in small pieces of fragile films. Finally, it can be suggested that the presence of TPS brought to the biodegradation of blends in soil burial test, while incorporating with PLA led to retardation in degradation rate.