STRUCTURES AND MECHANICAL-PROPERTIES OF MICROCELLULAR FOAMED POLYVINYL-CHLORIDE

In this paper, microcellular foamed polyvinyl chloride (PVC) with uniq ue cell morphology and mechanical properties is characterised. Microce llular foamed structures were produced in PVC by first saturating the polymer with CO2 under high pressure followed by rapidly decreasing th e solubility of CO2 in the samples. The void fraction of the microcell ular foamed PVC was controlled by tailoring the foaming temperature an d foaming time. Tensile and impact tests were performed on the foamed PVC to investigate the dependence of these properties on the void frac tion of foamed specimens. The notched Izod impact strength of microcel lular foamed PVC increased as the void fraction increased. When the vo id fraction was 80%, the notched Izod impact strength of foamed PVC wa s four times as high as that of the unfoamed PVC. However, the tensile strength and modulus decreased as the void fraction increased. Experi mental results indicate that the relative density of microcellular foa med PVC should be determined in consideration of the material saving, weight reduction, enhanced impact strength and reduced tensile strengt h and modulus to optimise performance of the foamed materials.