Structures and Mechanical Properties of Microcellular Foamed Polyvinyl Chloride

In this paper, microcellular foamed polyvinyl chloride (PVC) with unique cell morphology and mechanical properties is characterised. Microcellular foamed structures were produced in PVC by first saturating the polymer with C02 under high pressure followed by rapidly decreasing the solubility of C02 in the samples. The void fraction of the microcellular foamed PVC was controlled by tailoring the foaming temperature and foaming time. Tensile and impact tests were performed on the foamed PVC to investigate the dependence of these properties on the void fraction of foamed specimens. The notched Izod impact strength of microcellular foamed PVC increased as the void fraction increased. When the void fraction was 80%, the notched Izod impact strength of foamed PVC was four times as high as that of the unfoamed PVC. However, the tensile strength and modulus decreased as the void fraction increased. Experimental results indicate that the relative density of microcellular foamed PVC should be determined in consideration of the material saving, weight reduction, enhanced impact strength and reduced tensile strength and modulus to optimise performance of the foamed materials.