Thermal behaviors and characteristics of polylactide/poly(butylene succinate) blend films via reactive compatibilization and plasticization

摘要

> Polylactide (PLA)/poly(butylene succinate) (PBS) blend films modified with a compatibilizer and a plasticizer were hot‐melted through a twin screw extruder and prepared by hydraulic press. Toluene diisocyanate (TDI) and polylactide‐ grafted ‐maleic anhydride (PLA‐ g ‐MA) were used as compatibilizers, while triethyl citrate and tricresyl phosphate acted as plasticizers. The effects of the type and content of compatibilizer and plasticizer on the mechanical characteristics, thermal properties, crystallization behavior, and phase morphology of the PLA/PBS blend films were investigated. Reactive compatibilization at increasing levels of TDI improved the compatibility of the PLA and PBS, affecting the toughness of the films. As evidenced by scanning electron microscope, the addition of TDI enhanced the interfacial adhesion of the blends, leading to the appearance of many elongated fibrils at the fracture surface. Furthermore, PLA/PBS blending with both TDI and PLA‐ g ‐MA led to an acceleration of the cold crystallization rate and an increment of the degree of crystallinity ( χ c ). Toluene diisocyanate could be a more effective compatibilizer than PLA‐ g ‐MA for PLA/PBS blend films. The synergistic combination of compatibilizer and plasticizer brought a significant improvement in elongation at break and tensile‐impact toughness of the PLA/PBS blends, compared with neat PLA. Their failure mode changed from brittle to ductile due to the improved compatibility and molecular segment mobility of the PLA and PBS phases. Differential scanning calorimeter results revealed that the plasticizers triethyl citrate and tricresyl phosphate changed the thermal behavior of T _{c c} and T _m , affecting α ′ and α crystal formations. However, these plasticizers only slightly improved the thermal stability of the films.