The effect of talc on the crystal orientation in polypropylene/ethylene-propylene rubber/talc polymer blends in injection molding

The effect of talc on the b-axis orientation of the polypropylene crystals in polypropylene (PP)/ethylene-propylene rubber (EPR)/talc blends of injection molding was examined using the X-ray diffraction method. The b-axes of the PP crystals were most strongly oriented in the thickness direction for the injection molded PP/EPR/talc blends. The b-axis orientation in the thickness direction of injection moldings was promoted by increasing the concentration of talc, by reducing the particle size, or by purifying the talc. The dependence of the specimens' rigidity on talc content, particle size, and purity was also investigated. The rigidity depended on the degree of b-axis orientation. The results of our investigation suggest that increasing the orientation of the PP crystals that are near talc particles may improve the rigidity.