Toughening poly(3-hydroxybutyrate) with propylene carbonate plasticized poly(propylene carbonate)

Abstract

AbstractPoly(3-hydroxybutyrate) (PHB)/poly(propylene carbonate) (PPC) blends containing various amounts of plasticizer propylene carbonate (PC) were prepared, and the toughness of the blends as a function of temperature was studied. It was found that the brittle-ductile transition temperature (TBD) of PHB toughened by PPC decreased from 60°C to 10°C with the increase in PC content. As PC is the plasticizer of PPC, the mechanical properties, such as Young’s modulus of plasticized PPC with different PC contents, were also studied. Sequentially, the relationship between TBD and the ratio of the Young’s modulus (E1) of the PHB matrix to that of the plasticized PPC elastomer (E2) was investigated. It was found that the Young’s modulus of plasticized PPC should be considerably lower than that of the PHB matrix in order to obtain ’the tough PHB/plasticized PPC blends at a lower temperature. In contrast, the morphology of the dispersed particles also had an important influence on the toughness. When the plasticizer content was more than 20 wt.%, the PPC particles became more spherical and smaller. The toughness could be considerably improved accordingly.