Phase Morphology and Miscibility of iPP/PcBR Blends

Isotactic polypropylene/poly(cis-butadiene) rubber (iPP/PcBR) blends were prepared by melt mixing. Phase morphology of the blends was investigated by scanning electronic microscopy (SEM). It was found that the dispersed phase spread in continuous phase in a form of spherical particles. The size of the dispersed phase increased as its content increased. The phase-inversion region was the composition of 50/50 and 40/60 vol% in the blends. In the phase-inversion region, a double continuous phase was formed. The glass transition temperatures (T g ) of iPP, PcBR and blends were analyzed by dynamic mechanical analysis (DMA). The blend compositions exhibited two distinct glass transition temperatures corresponding to the iPP-rich and PcBR-rich phases, respectively. The approach of these two peaks with increasing PcBR content indicated partial miscibility between the iPP and PcBR, which was verified by the equilibrium melting point depression of blends.