(8a) Study of Super-Toughed Poly(lactic acid) Ternary Blends Prepared by Dynamic Vulcanization-Induced Compatibilization

In this work, the preparation of poly(lactic acid) (PLA) ternary blends consisting of PLA, an epoxy-containing terpolymer elastomer and an ionomer of ethylene-methyacrylic acid copolymer and investigation of mechanical and physical properties of the resulting blends were investigated. The blending was performed in a twin-screw extruder. The curing of the elastomer by the ionomer took place during compounding and reactive compatibilization between the cured elastomer phase and the PLA matrix was also established. The reaction process under different conditions was assessed by performing the mixing in a torque theometer, the reaction products were isolated and examined by FT-IR. Mechanical, thermal dynamic mechanical properties and morphology of the blends were thoroughly studied. The ionomer/elastomer weight ratio was varied, but the ionomer and elastomer content was fixed at 20 wt% in the blend. Extrusion temperature, elastomer/ionomer ratio, cation type and neutralization degree of the ionomer all had significant effects on impact toughness of the ternary blends. Super-toughness was successfully obtained for some blends compounded at 240?aC. It was found that zinc ionomer initiated and catalyzed the dynamic vulcanization of epoxy-containing elastomer, and it also promoted the reactive compatibilization at the interface between PLA and elastomer. TEM observation revealed that the °¥salami'-like phase structure was formed in the ternary systems. The effective reactive interfacial compatibilization at elevated blending temperatures was believed to be responsible for the significant increase in notched impact strength rather than enhanced crystallization of PLA matrix.