INFLUENCE OF DIFFERENT BLOWING AND NUCLEATING AGENTS ON THE DEGASSING PRESSURE AND THE FOAM MORPHOLOGY OF PHYSICALLY FOAMED POLYPROPYLENE

摘要

The aim of this study was to investigate the effect of different combinations of blowing and nucleating agents on the foam morphology of extrusion foamed polypropylene high density foam sheets. In order to improve the understanding of the influence of the blowing and nucleating agent on the foaming process, the degassing pressure was determined with an optical spectroscopy technique. Furthermore the different combinations of the blowing and nucleating agents were used to manufacture high density foam sheets with a semi industrial extrusion line. The experiments were carried out with two different lip geometries of the die to realize different flow conditions. The foamed sheets were characterized in terms of mean cell size, cell density, density and surface roughness.