Crystal orientation in injection moldings of talc-filled polyolefins

Crystal orientation states in injection moldings of talc-filled polyolefins have been studied. Talc-filled polypropylene injection moldings show an unusual crystal orientation, in which the plate planes of talc particles are aligned parallel to the molding surface, the c- and a*-axes of polypropylene crystals are bimodally oriented to the flow direction, and the b-axes are oriented to the thickness direction. In injection moldings of talc-filled high density polyethylene and polybutene-1, although talc particles are aligned parallel to the molding surface, polymer crystals do not show any unusual orientation. Only talc-filled polypropylene injection moldings show the unusual crystal orientation.