Effect of pressure and shear stress on crystallization behaviors in injection molding

We studied in detail the effects of pressure and shear stress on the crystallization behaviors during injection molding process. Crystallization of isotactic-polypropylene (iPP) was simulated for various injection flow rates. The crystallization started during the filling stage under long filling condition. Moreover, the crystallization in some layers showed two-step growth behavior, while in other layers the crystallization does not progress during the packing-cooling stage. Since pressure becomes very high during molding process under long filling time condition, the change of pressure is the most important factor governing the crystallization.