A new microcellular composite material with a biomimetic structure has been prepared via the supercritical fluid (SCF) technology. The resultant material has a clear biomimetic structure like bamboo and wood. The skin region is enriched with oriented high-strength thermotropic liquid crystal polymer fibrils, while the core region with polystyrene (PS) micro-cells. The diameter and density of micro-cells can be controlled by the processing parameters such as temperature and pressure. And the skin thickness can be controlled conveniently by varying the composition of polystyrene and liquid crystal polymer.
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.
Two cyclic olefin copolymers with the same comonomers and different monomer molar ratios were blended,and then the blends were satura ted in supercritical CO 2 at 20?MPa and various temperatures to prepare microc ellular cyclic olefin copolymer blends by means of pressure quench.The cell dens ity and cell diameter of microcellular polymers were calculated to investigate t he effects of temperature and blending ratio on cell structures.The higher tempe rature results in larger cell sizes and smaller cell densities.The cell density increases remarkably and cell diameter decreases with increase in the content of the ingredient with higher T g.It is found that the stiffness of the matri x is the only possible material property that accounts for the differences in ce ll structure of micorocellular cyclic olefin copolymer blends with different ble nding ratio.
