Oscillatory shear induced γ-phase growth of metallocene-made isotactic polypropylene

The influence of temperature and oscillatory shear on the formation of γ-phase in metallocene-made isotactic polypropylene (m-iPP) has been investigated by two dimension X-ray diffraction (2D-WAXD) and differential scanning calorimetery (DSC). From skin to core, the amount of the γ-phase raises continuously in samples fabricated by conventional injection molding (CIM), which is mainly due to the thermodynamic factor. Interestingly, when sample was fabricated by oscillatory packing injection molding (OPIM), the amount of the γ-phase raises as a wave-like pattern from skin to core as a result of the competition between the thermodynamically controlled and oscillatory shear induced crystallization. The result of 2D-WAXD and DSC show the same changing tendency from skin to core.