Ken-ichi Mukaida

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.

Density measurement of small porous particles by mercury porosimetry

Abstract The concept of density of solid particles is discussed, and the relation between these concepts and the different measurement methods is considered with the emphasis on the porousness (i.e. the property of ‘porous’ or ‘non-porous’) of the solid particles. Mercury porosimetry was used to determine the density of porous small particles. The limitations of this method and the influence of surface roughness and other particle characteristics on the density values obtained are also discussed.

Thermotropic liquid-crystalline polymers having five-membered heterocycles as mesogens—2. Homo- and copolymers composed of 1,3- or 1,4-phenylenebis(1,3,4-thiadiazole 2,5-diyl) unit

Abstract New homo-and copolyhydrocarbons composed of 1,3-and/or 1,4-phenylenebis(l,3,4-thiadiazole-2,5-diyl) units were successfully prepared by intramolecular cyclization of the corresponding polyhydrazides, which were synthesized by direct polycondensation of terephthalhydrazide and/or isophthalhydrazide with 1,18-octadecanedicarboxylic acid, with diphosphorus pentasulphide in pyridine. Spectroscopical measurements, elemental analysis data and thermogravimetric analyses (TGA) suggested that the intramolecular cyclization completely proceeded. Differential scanning calorimetry (DSC) measurements, optical texture observation by means of polarizing microscope and powder X-ray analyses indicated that only the 1,4-phenylenebis(l,3,4-thiadiazole-2,5-diyl) unit-rich copolymer (80 mol.%) formed thermotropic liquid-crystalline smectic phase, but the others had birefringent or normal melts. The phase transition temperatures (melting and isotropization) had a tendency to change non-linearly with the 1,4-phenylenebisthiadiazole composition.

New polymethacrylates having a carbonate linkage between the spacer and the mesogenic unit in the side chain

New side chain homo- and copolymethacrylates with a carbonate linkage between the spacer and the mesogenic unit were prepared by the free radical polymerization of monomers having 4-cyanobiphenyl and/or 4′-methoxybenzylideneaniline as mesogens, whose structures were confirmed by FTIR and 1H-NMR spectra and elemental analyses. Thermal and mesogenic properties of the monomers and the polymers were evaluated by differential scanning calorimetry, X-ray analyses and polarizing microscopy. It was discovered that only the homopolymer with 4′-methoxybenzylideneaniline as a mesogen formed nematic mesophase, but the others had no thermotropic LC phases. This might be due to introduction of a carbonate linkage which shows an unusual geometry.

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.

Synthesis and liquid-crystalline properties of thermotropic polyamides containing flexible rodlike units and aliphatic spacers

Abstract New polyamides with high molecular weights consisting of flexible rod-like mesogenic units (4,4′-diphenyl and 3,4′-diphenyl moieties having bent linkages in the central parts) and aliphatic spacers were synthesized and the thermotropic liquid-crystalline properties were investigated. Differential scanning calorimetry, texture observations by polarizing microscopy, miscibility tests and X-ray analysis suggested that the polymers showed well-defined thermotropic smectic mesophases. The polyamides containing 4,4′-diphenyl moieties had higher transition temperatures and formed more stable liquid-crystalline phases than the polyamide composed of the 3,4′-diphenyl unit with a kinked bond.

Synthesis and mesogenic properties of polyurethanes containing a naphthalene ring

Abstract New polyurethanes with high inherent viscosities of 1.74–2.10 dl/g in 1,1,1,3,3,3-hexafluoro-2-propanol were prepared by melt polycondensation of a 2,6-dioxydihexanol derivative of naphthalene, prepared from naphthalene-2,6-diol and 6-chloro-l-hexanol, with even alkylene diphenyl dicarbamates (n = 6, 8, 10 and 12). The structures of the polymers were confirmed by FTIR, 13C-NMR spectra and elemental analyses. Thermotropic liquid-crystalline (LC) properties of the polyurethanes were evaluated by differential scanning calormetry, by optical texture observation with a polarizing microscope and with a X-ray diffractometer. It was discovered that the polyurethanes having only the naphthalene ring could form nematic LC textures in spite of low aspect ratio of the mesogenic unit.

Wet friction materials for continuous slip torque converter clutch – Fuel economy improvement of passenger cars equipped with automatic transmission –

It was found that activated carbon possessed remarkably higher heat of adsorption for ATF additives (automatic transmission fluid additives) than any other materials contained within the clutch facing. Friction performance tests in low sliding velocity range were conducted for two kinds of clutch facings, containing activated carbon powder or graphite one as key ingredients for adsorption. As the additives mixed to the base oil to form the testing oils, polybutenyl succinimide (SI) was selected as a dispersant, and tricresyl phosphate and dialkyl phosphite were selected as a friction modifier. The results showed that the combination in activated carbon with SI was most effective to improve the initial anti-shudder performance of continuous slip torque converter clutch (CSTCC). It is considered that this effect was due to the strong adsorption of SI to the surface of activated carbon in the clutch facings.

Side-chain liquid crystalline homo- and copolymethacrylates with a carbonate linkage between the benzylideneaniline mesogen and ethylene chain

Abstract New liquid crystalline (LC) homo- and copolymethacrylates having a carbonate linkage between a benzylideneaniline mesogen and ethylene chain in the side chain were prepared by free radical polymerization of methacrylate derivatives comprising 4-cyano- and/or 4-methoxybenzylide-neaniline units using AIBN as an initiator. The structures of the polymers were characterized by FTIR, 1HNMR, and elemental analyses. The LC properties were evaluated by differential scanning calorimetry (DSC), polarizing microscopic observation of textures and X-ray diffraction. These measurements showed that all the homo- and copolymers form nematic phases. The isotropization temperatures on composition exhibited a negative deviation from a linear relationship between them predicted by the Schroeder-Van Laar equation. This phenomenon might be caused mainly by an unusual geometry arising from a smaller bond angle in the carbonate linkage.

Synthesis of Layered-Structure LiFeO2

Abstract LiFeO2, with a layered rocksalt structure of α-NaFeO2-type was prepared by ion exchange reaction from Na+ ion to Li+ ion using α-NaFeO2. α-NaFeO2-type LiFeO2 was synthesized by using the mixture of LiI and KI in the temperature range 220 to 480 °C. The heat treatment temperature of 600 °C gave α-LiFeO2-type LiFeO2 as a main product. As a result of Rietveld analysis, the structure of LiFeO2 which assigned to α-NaFeO2-type by an XRD measurement, was the mixture of α-NaFeO2-type and Li-intercalated spinel-type structures.