Two cyclic olefin copolymers with the same comonomers and difierent monomer molar ratios were blended

and then the blends were saturated in supercritical CO2 at 20 MPa and various temperatures to prepare microcellular cyclic olefin copolymer blends by means of pressure quench．The cell density and cell diameter of microcellular polymers were calculated to investigate the effects of temperature and blending ratio on cell structures．The higher temperature 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 hisher Tg．It is found that the stiffness of the matrix is the only possible material property that accounts for the differences in cell structure of micorocellular cyclic olefin eopolymer blends with difierent blending ratio．