The Characterization Of Hierarchy Structure In Injection Molded Polypropylene Blending System

Studying the physical problem during the polymer molding process, combining the polymer physics and polymer molding process, and the research on the control of the morphology of polymer blends are one of the hot research fields in the polymer science at present. In this work, PP blending system is the research point. The morphology structure was controlled via the dynamic shear field and different processing conditions and its structure was deeply studied. The main results are listed here:First, we study the effect of miscibility on phase morphology and orientation of is tactic polypropylene (iPP) blends under shear stress was investigated via dynamic packing injection molding (DPIM). The miscibility's of iPP blended with other polymers, namely, atactic polypropylene (aPP), octane-ethylene copolymer (POE), ethylene-propylene-diene rubber (EPDM) and poly (ethylene-co-vinyl acetate) (EVA), have been first studied using dynamic mechanical analysis (DMA). These blends were subjected to DPIM, which relies on the application of shear stress fields to the melt/solid interfaces during the packing stage by means of hydraulically actuated pistons. The phase morphology, orientation and mechanical properties of the injection-molded samples were characterized by SEM, 2D WAXS and Instron. For immiscible iPP/EVA blends, a much elongated and deformed EVA particles and a higher degree of iPP chain orientation were observed under the effect of shear. However, for miscible iPP/aPP blends, a less deformed and elongated aPP particles...