Plane-compression properties of microcellular injected polypropylene using gas counter pressure and core-back expansion process

Microcellular Polypropylene (PP) was obtained using Chemical Blowing Agents (CBA) in a injection process combined with Gas Counter Pressure (GCP) and core-back expansion molding. Two different types of PP, neat and charged, were mixed with a fixed proportion of CBA and injected into a plate, obtaining structural foams with a foamed core and solid outer skins. After, the plate morphology is analyzed to evaluate the main morphological parameters, such as cell size and thickness of the outer skin. The results show that the type of CBA has a great influence on the cell size. Finally, low velocity plane compression tests were carried out in the structural foams at a fixed strain rate to obtain the Young’s modulus of the foamed core and also the whole structure, using some theoretical approaches to evaluate the effect of foam density in the obtained results.