Study of Thermal and Mechanical Properties of Tertiary Blend of Poly(lactic acid), Poly(hydroxybutyrate-co-hydroxyvalerate) and Thermoplastic starch

Nowadays, single-use plastics such as straws, plastic bags cause plastic waste problems because the majority of these plastics which are petroleum-based plastics are not compostable and difficult to recycle. As a result, biodegradable plastic is a proper option to replace traditional plastic. The objective of this work was to study the morphology as well as the thermal and mechanical properties of tertiary blend of poly(lactic acid) (PLA), poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and thermoplastic starch (TPS). PLA/PHBV at weight ratios of 80/20, 70/30, and 60/40 were prepared to find the optimal ratio. Then the PLA/PHBV at weight ratio of 80/20 was added by TPS 1,5 and 10 phr. The cast-film extrusion was used to prepare film sheets. It was found that the addition of PHBV in PLA/PHBV blends led to an increase in tensile properties. However, the addition of TPS in PLA/PHBV/TPS blends brought about lower in tensile properties. SEM micrographs revealed that PLA/PHBV blends were not miscible and the addition of TPS in PLA/PHBV/TPS blends affected their mechanical properties. Moreover, DSC data indicated that the addition of PHBV and TPS had significantly affected the thermal properties of film sheets.