Influence of heterogeneous textures of polypropylene/ethylene–propylene–rubber blends on dynamic viscoelastic properties in the solid

Abstract

Heterogeneous textures in phase separated, solid polypropylene (PP)/ethylene–propylene–rubber (EPR) blends were investigated in relation to their dynamic viscoelastic properties. The glass transition temperature (Tg) of amorphous PP phase in PP/EPR blend quenched from molten state varies with propylene content of EPR as well as EPR content in blend. The Tg depends on the concentration of EPR dissolved in the amorphous PP phase. On the other hand, the Tg of EPR phase in PP/EPR blend is about the same as that of pure EPR. This fact means that PP molecules were not dissolved in EPR phase. For the same blending composition, the EPR concentration in matrix PP phase was larger for EPR having more propylene units. When the same EPR was used, the EPR concentration in the matrix was larger for blends with larger EPR content. The EPR concentration in the amorphous PP phase of PP/EPR blend in solid state is about the same as that in molten state, indicating that the EPR concentration in solid state was essentially determined by the EPR concentration in molten state.