Microcellular polystyrene/LCP in situ composites with cell diameter less than 4 μm are prepared by using pressure quenching after supercritical CO 2 saturating at 25?MPa, 80℃ for 6 h. Characterization of the microcellular structure of these blends is conducted to reveal the influence of LCP addition, LCP ratio and compatibilizer on the microcellular blends. The typical structure of these microcellular PS/LCP blends is that the microvoids only exist in the polystyrene phase. This structure results from the poor adsorption of supercritical CO 2 by LCP under the experimental conditions. The cell diameter of the microcellular blends is smaller than that of microcellular PS. An increase of cell size is also found from skin to core in microcellular blends. The microcellular blends with ZnSPS has larger cell size than those without ZnSPS, which is the consequence of the improvement of interfacial adhesion. It is because CO 2 could easily diffuse out through the gap between poor adhesion interface of blends without ZnSPS.
The effect of supercritical fluid on morphology of polystyrene in gas assisted injection molding was studied,the SEM result showed that the morphology of polystyrene treated by supercritical fluid nitrogen gas was very different from that of untreated polystyrene.There was a laminar structure in treated polystyrene that induced by fountain flow when the melt was propelled by the gas in gas assisted injection molding.It was also found that gas penetration induced the occurrence of self similar structure,e.g.fractal structure which was related with viscosity finger effects.
