The Crystal orientation states in injection moldings of polypropylenes filled with flaky fillers such as glass flake, mica, and talc have been studied. Talc-filled polypropylene injection moldings show a peculiar crystal orientation, in which the planes of the talc particle plates are aligned parallel to the molding surface, the c- and a*-axes of polypropylene crystals are bimodally oriented in the flow direction, and the b-axes are oriented in the thickness direction. Although an unfilled polypropylene injection molding basically shows a similar crystal orientation to that of the talc-filled polypropylene injection molding, the b-axis orientation to the thickness direction is much weaker. Glass flake- or mica-filled polypropylene injection moldings show a similar crystal orientation to that of the unfilled polypropylene injection molding. Only talc-filled polypropylene injection moldings show the peculiar crystal orientation. Since an injection molding of polypropylene filled with only 0.5wt% talc already shows the peculiar crystal orientation, it is assumed that talc has a remote influence on the crystallization of polypropylene.

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Straight lines drawn on a film were deformed into parabolic ones after passing through the annealing zone of a tenter. It became theoretically evident that shear stress acted backward along the film in proportion to the distance from the center to the edge. The optical anisotropy, which was generated in the tenter and depended on the position on the film, was calculated, assuming that the refractive index ellipsoids were deformed in proportion to the shear stress. The results follow: 1. The refractive index ellipsoid of the film is not deformed at the center of film. 2. The birefringence patterns (birefringence∼transverse position) are downward convex and had a minimum near the center of the films. 3. The birefringence increases in proportion to the distance from the center to the edge, when the initial birefringence is zero. 4. The planar orientation is unaffected by heat-setting at any location in the films. 5. The angle of γ is 90° at the center of the film and decreases from the center to the edge, when the initial γ direction is pararell to the machine direction. 6. The angle of γ is 0° at the center of the film and increases from the center to the edge, when the initial γ direction is perpendiculer to the machine direction.

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