Injection molding of isotactic polypropylene

Abstract

Injection molding is one of the widely used methods in the processing of isotactic polypropylene (iPP), where a screw in a heated barrel rotates to transport, melt and pressurize the polymer in the barrel, and then reciprocation of the screw injects the melt into the mold. Processing parameters have a very strong influence on the morphology and hence the physical properties of the molded product. This section discusses the effect of main processing parameters on the morphology and properties of conventionally injection-molded isotactic polypropylene. The application of shear controlled orientation in injection molding (SCORIM) for converting iPP into molded products is the subject of another chapter in this book, which presents the morphological changes induced in SCORIM with the objective of enhancing physical properties. These chapters together present the fundamental characteristics of injection-molded polypropylene which may serve as a guide to the more informed processing of iPP, and to the realisation of optimum physical properties.