Injection molding. Influence of process parameters on mechanical properties of polypropylene polymer. A first study.

TLDR

The authors designed an injection‑molding setup with pressure and temperature sensors, produced specimens for tensile, Charpy, and Hopkinson tests, and used a Design of Experiment to study the effects of melt temperature, mold temperature, packing pressure, and cooling time. The study found that mold temperature and holding pressure significantly affect the mechanical strength of polypropylene, establishing a clear correlation between injection‑molding parameters and material performance.

Abstract

This paper shows the first study results of the mechanical characterization of a commercial polypropylene (PP) polymer. Before testing, a mold for injection molding process has been designed and realized. Three different specimens can be produced, for three different tests: tensile, Charpy and Hopkinson bar. In-cavity pressure and temperature sensors are installed next to the molded item to have direct information about process phases. After the description of the instrumentation, the correlation between injection molding input parameters and mechanical behavior of the material has been assessed. In particular, tensile tests have been carried out to investigate the influence of: melt temperature, mold temperature, packing pressure and cooling time. A Design of Experiment plan has been set up to establish the tests to be performed. Results show the influence of mold temperature and holding pressure on mechanical strength of the polymer.