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 ellu...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.展开更多
A six-member cyclic carbonate with protected functional groups was synthesized from tetramethylolmethane,benzaldehyde and ethyl choroformate.Coplymerization of（D,L-lactide） with cyclic carbonate was carried out thro...A six-member cyclic carbonate with protected functional groups was synthesized from tetramethylolmethane,benzaldehyde and ethyl choroformate.Coplymerization of（D,L-lactide） with cyclic carbonate was carried out through conventional ring-opening polymerization using Sn（Oct）2 as the catalyst.The effects of different catalysts,polymerization time and monomer-to-catalyst molar ratio on the molecular weight were investigated.The methods of removing protected groups were studied.Results showed the protected groups were effectively removed via catalytic hydrogenation.（Poly（D,L-lactide-co-cycliccarbonate）s） with hydroxyl pendant functional groups was obtained.展开更多
文摘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.
文摘A six-member cyclic carbonate with protected functional groups was synthesized from tetramethylolmethane,benzaldehyde and ethyl choroformate.Coplymerization of（D,L-lactide） with cyclic carbonate was carried out through conventional ring-opening polymerization using Sn（Oct）2 as the catalyst.The effects of different catalysts,polymerization time and monomer-to-catalyst molar ratio on the molecular weight were investigated.The methods of removing protected groups were studied.Results showed the protected groups were effectively removed via catalytic hydrogenation.（Poly（D,L-lactide-co-cycliccarbonate）s） with hydroxyl pendant functional groups was obtained.
