Effects of ionomer characteristics on reactions and properties of poly(lactic acid) ternary blends prepared by reactive blending

Toughening of poly(lactic acid) (PLA) was studied by reactive blending PLA with ethylene/n-butyl acrylate/glycidyl methacrylate (EBA-GMA) terpolymer and zinc ion-containing ionomer. The ionomer was prepared by neutralizing the ethylene/methacrylic acid copolymer (EMAA), i.e., ionomer precursor, with ZnO. The reactive interfacial compatibilization between PLA and EBA-GMA and the crosslinking of EBA-GMA during blending was studied in detail. Fractography and FT-IR analysis indicated that both the degree of neutralization (DN) of ionomer and methacrylic acid (MAA) content of ionomer precursor exhibited significant effects on interfacial compatibilization. Dynamic mechanical analysis also suggested that the crosslinking level of EBA-GMA varied with these two factors. Particle size and polydispersity of the dispersed phase were measured by image analysis of TEM micrographs of the ternary blends and correlated with the impact strength of the blends and the characteristics of the ionomer. Ionomers derived from precursor of high MAA content and/or having high DN tended to yield superior impact strength of the PLA blends.