Synergistic Effects of Modification with Nanociay and Polystyrene on the Foaming Behavior of a Random Copolymerized Polypropylene

摘要

Microcellular polypropylene/polystyreneanociay (PP/PSanoclay) composites were processed in a continuous extrusion foaming system using supercritical CO2 as the foaming agent. Neat PP foam showed quite a broad distribution of cell sizes and thick cell walls. Under the same foaming conditions, nanociay and PS were introduced in the foaming process of PP. Consequently, foams with uniform cell size distribution, reduced cell size of 10-30 μm and enhanced cell-population density of 2.16x10~8 cells/cm~3 were obtained. The heterogeneous nucleation of PS and nanociay dramatically increased the nucleation rate, decreased the nucleation time interval, and hence facilitated an almost instantaneous growth of cell size. This method also provided new insight into the mechanism of improving the foaming performance of PP.