Microcellular Foaming of Polypropylene/Clay Nanocomposites with Supercritical Carbon Dioxide

The solid-state foaming of two series of polypropylene (PP)/clay nanocomposites based on two different types of organoclays were studied. The wide-angle X-ray diffraction results showed that a supercritical carbon dioxide (scCO 2 ) saturation process could lead to the further exfoliation of clay when the initial interlayer spacing was larger enough. It was found that the incorporation of clays exerted significant impacts on cell nucleation and growth and the effect of clays was determined by their dispersion state. However, the influence of clay on the foaming of the PP/clay nanocomposites became marginal at a higher saturation pressure and a lower foaming temperature.