THE INFLUENCE OF INTERFACIAL INTERACTIONS ON THE MORPHOLOGY AND THERMAL-PROPERTIES OF BINARY POLYMER BLENDS

In order to understand the influence of interfacial modification in polyamide/ionomer/polypropylene ternary blends, the binary blends were investigated. In this study two multiphase blends have been chosen, PP/ionomer and PA/ionomer, where the ionomer was a copolymer of polyethylene and of a mixture of methacrylic acid, zinc methacrylate and isobutylacrylate. The PP/ionomer blend is a classic example of an incompatible system which displays a high degree of interfacial voiding in SEM fracture surfaces, a strong negative deviation from additivity in the viscosity/composition relationship and an important coalescence effect on increasing dispersed phase concentration. This blend demonstrated increased nucleation and crystallization rate, compared to pure polypropylene. The second blend, PA/ionomer, demonstrates a very fine multiphase structure evident only after microtoming/etching of the sample, strong additive behaviour in the viscosity/composition curve. Formation of an amide bond was identified by Fourier transform infrared spectroscopy. This evidence supports the conclusion that much stronger interactions exist between the ionomer and the polyamide than between the ionomer and the polypropylene.