Preparation of Microcellular Polyurethane Using Supercritical Carbon Dioxide

Microcellular foam of a thermoplastic polyurethane (TPU) elastomer, synthesized from polycarbonatediol, 4,4'-diphenylmethane diisocyanate and 1,4-buthanediol, was prepared using supercritical carbon dioxide. The influence of foaming time and temperature on cell structure was investigated. Although the foaming temperature had no effect on cell number density in the microcellular foam, it affected the average cell size. The tensile strength at break of TPU deteriorated with the increase in the void fraction resulting from microcellular foaming. However, the specific tensile strength was independent of the void fraction.