Simulation of Crystallization in Injection Molding Process with a Large Mold

Abstract

We have calculated the crystallization of isopolypropylene (iPP) during injection molding in the case of large molded products. Due to the long filling time, the crystallization started during the filling stage just inside the surface layer of the product. On the other hand, the relative crystallinity at the surface did not reach 100% even at the end of the cooling stage. Since pressure becomes very high during the molding process of large products, the dependence of the linear growth rate of spherulite G not only on temperature but also on pressure is very important in determining the crystallization. At the surface of the product, low temperature and high pressure make G so low that the crystallization does not complete even at the end of the cooling stage.