Noboru Takeno

Compatibilizing effect of thermotropic liquid crystalline block-graft copolymer on liquid crystalline polycarbonate-polystyrene blend systems

Abstract Thermotropic liquid crystalline (LC) block-graft copolymer (LCBG) composed of thermotropic LC polycarbonate (LCPC) in the backbone and polystyrene (PS) segment in the side chain (reported previously) was added to incompatible polymer blend systems of thermotropic LCPC and commercial PS as a compatibilizer. The compatibility, morphology and mechanical properties of the blends were evaluated by SEM, DSC and TMA measurements. No compatibility between the LCPC and the PS was found in the LCPC-PS blend systems (LCPC: PS = 2:8) but the SEM examination indicated that fibrils were formed in the systems to which the LCBG was added. This finding means that the compatibility between LCPC and PS is improved. Data for glass transition steps by DSC measurements support this view. The blend system containing LCBG (5 wt%) showed the best mechanical properties of all the systems. These results suggest that LCBG is a useful compatibilizer for the blend systems.

Synthesis and liquid crystallinity of thermotropic polycarbonate-polystyrene graft copolymers

Abstract Thermotropic liquid crystalline polycarbonate-graft-polystyrene copolymers were synthesized by the macromonomer method using melt polycondensation of a mixture of 6,6′-(4,4′-biphenylylenedioxy)dihexanol and styrene macromonomer with hexylene diphenyl dicarbonate taken in a definite molar ratio. The graft copolymers were characterized by FT-i.r spectra and elemental analysis. Their liquid crystallinites were investigated by differential scanning calorimetry and polarizing microscopy using a hot stage. Some of the products, except for polymers rich in styrene macromonomer, showed liquid crystallinites arising from the parent homopolycarbonate and had microphase-separated structures.

Epoxidation of ethylene over silver catalysts modified by sodium chloride

the selectivity of epoxide synthesis in the direct oxidation of ethylene is increased to 85–87% by addition of sodium chloride to the silver catalyst; this selectivity corresponds to the maximum expected by mechanistic studies.