Polylactic Acid and Poly(Butylene Adipate-Co-Terephthalate) Blends Plasticised with Lactic Oligomers and Epoxy Reactive Plasticizers

Abstract

Polylactic acid (PLA) is a compostable and sustainable polymer, derived from renewable resources, with high elastic modulus and high transparency. By the way PLA has even some limitations such as low glass transition temperature, low thermal stability, high brittleness, and low crystallization rate. To increase flexibility of PLA based materials it is possible to add low molecular weight plasticizers or prepare blends with another flexible polymer, such as poly(butylene adipate-co-terephthalate) (PBAT). Even the use of a compatibilizer may allow a modulation of mechanical properties thanks to the achievement of a phase morphology characterized by a lower dimension of the dispersed PBAT phase and an increased adhesion. In the present study, blends of PLA and PBAT were prepared by adding different plasticizers combinations based on an oligomer of lactic acid, a polyester of adipic acid and 1,2-propane diol, and an epoxy functionalised resin. All the plasticizers were effective in providing flexibility to the blends, with higher efficiency from the epoxy functionalised plasticizer, and the polyester of adipic acid. Fox’s equation showed that all plasticizers have the tendency to disperse more in the amorphous PBAT matrix than in the PLA one.