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Volume 43, Issue 5
Displaying 1-11 of 11 articles from this issue
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Akihiro ABE, Hidemine FURUYA1986 Volume 43 Issue 5 Pages 247-252
Published: May 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe role of the soft-spacer incorporated in the main-chain type liquid crystalline polymers has been studied via a conformational analysis of the chain. The angle θ defined by unit vectors attached to two successive rigid cores has been evaluated for each conformation of the intervening flexible segments. The details of the analytical procedure have been described in our previous paper, in which polyesters such as XOC (O) (CH2) nC (O) OX (X=mesogenic core) were treated. In the present report, the analysis has been extended to systems such as polyethers XO (CH2) nOX, polycarbonates XOC (O) O (CH2) nOC (O) OX, and polyethers of the type X (OCH2CH2) xOX. These polymers are all known to exhibit thermotropic nematic liquid crystals. The observed even-odd oscillation in various thermodynamic quantities such as TNI, Sim and ΔSNI with the chain length n (or x) was found to be explicable in terms of the geometrical characteristics of the chain.View full abstractDownload PDF (955K) -
Toshihide INOUE, Masaru OKAMOTO, Toshimasa HIRAI1986 Volume 43 Issue 5 Pages 253-259
Published: May 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSPolyarylates obtained from substituted hydroquinones and 4, 4′-diphenyldicarboxylic acid showed liquid crystallinities at the temperatures lower than 425°C in spite of their rigid chemical structures. For the polyarylates from chlorohydroquinone or methylhydroquinone and terephthalic acid, however, no liquid crystallinities were observed at the temperatures lower than 500°C. Fibers of polyarylates prepared from substituted hydroquinones, 4, 4′-diphenyldicarboxylic acid, and terephthalic acid showed high Young's modulus (11-95GPa).
These tensile fractured fibers were composed of two types of fibrillar structures, needle-like fibrils parallel to the flow direction and plate-like fibrils transverse to the flow direction, as indicated by scanning electron microscopy. The Young's Modulus of the former structure was larger than the latter.View full abstractDownload PDF (2396K) -
Toshihide INOUE, Masaru OKAMOTO, Toshimasa HIRAI1986 Volume 43 Issue 5 Pages 261-267
Published: May 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSA number of thermotropic polyarylate have been prepared from substituted hydroquinone, 1, 2-bis (phenoxy) ethane-4, 4′-dicarboxylic acid and 1, 2-bis (2-chlorophenoxy) ethane-4, 4′-dicarboxylic acid. A fiber from methyl-hydroquinone 1, 2-bis (2-chlorophenoxy) ethane-4, 4′-dicarboxylate showed a Young's modulus of 72GPa (0.11mmφ), which would be the highest value ever reported for homopolyarylates. 2, 7-Dihydroxynaphthalene 1, 2-bis (phenoxy) ethane-4, 4′-dicarboxylate and 1, 2-bis (2-chlorophenoxy) ethane-4, 4′-dicarboxylate have also been prepared. The former showed a liquid crystallinity, in spite of its asymmetrical structure, while the latter showed no liquid crystallinity.View full abstractDownload PDF (1833K) -
Matsumasa KYOTANI, Hisaaki KANETSUNA1986 Volume 43 Issue 5 Pages 269-276
Published: May 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSIn order to investigate relations between thermal behavior and microstructural properties of four thermotropic polysters, (1. X=Cl, 2. X=Br, 3. Y=Cl, 4. Y=Methyl), their thermal behavior was examined by differential scanning calorimetry on cooling from the anisotropic and isotropic melts of these polymers at a cooling rate of 20°C/min. Fracture surfaces of the polymers cooled from the isotropic and anisotropic melts in the DSC pan were observed by scanning electron microscopy. The polymers cooled from the anisotropic melt show crystallinity and have microstructures which are shaped like either ribbons or prisms. However, the crystallinity and the size of the microstructure are dependent upon the temperature at which the cooling of the polymers starts. The higher the temperature, the lower the crystallinity and the smaller the size of the microstructures. The transition of the anisotropic-isotropic melt of polymers 3 and 4 is observed on both heating and cooling. The polymers cooled from the isotropic melt show very low crystallinity, particularly polymer 3 is almost noncrystalline, and have uniformly fine structures. Microstructures formed on cooling from the isotropic melt are different from those formed on cooling from the anisotropic melt in the same way.View full abstractDownload PDF (2185K) -
Tetsuo KANAMOTO, Kazuhiro OSHIMA, Koji TANAKA, Naoyuki KOIDE, Kazuyosh ...1986 Volume 43 Issue 5 Pages 277-283
Published: May 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSOur previous proposal of a folded-chain model for the smetic copolyesters composed of azoxydibenzoate (mesogen group) and oligo-oxyethylenes (spacers) has been examined in terms of the orientation behavior of the molecular segments and the mesogen layers under shear flow induced during extrusion through conical dies. Small- and wide-angle X-ray diffraction analyses of the fibers extruded from smectic states revealed the characteristic orientation of the mesogen groups and their layers. The former oriented perpendicular to the extrusion direction (fiber axis) and the latter with the wide surfaces of lamelae parallel to the extrusion direction. These facts suggest that the basic flow units in the smectic phase have a lamellar structure which consists of mesogen layers. This basic structure in smectic states, as well as the orientation in solid (crystalline) state extrudates and the crystallization behavior from smectic states, suggests the prevalence of a folded-chain structure in smectic states, at least for the copolyesters studied in this work.View full abstractDownload PDF (2539K) -
Kazuhiro TOMOIKE, Ichiro TERADA, Kenji YAMADA, Naoyuki KOIDE, Kazuyosh ...1986 Volume 43 Issue 5 Pages 285-294
Published: May 25, 1986
Released on J-STAGE: March 25, 2010
JOURNAL FREE ACCESSThe relationships between molecular aggregation structures and gas permeation properties of thermotropic liquid crystalline polymers which have rnesogenic groups in the main chain and the side group were investigated. Differential scanning calorimetry (DSC), polarizing optical microscopic observation, X-ray diffraction and dynamic viscoelastic measurements were used. The permeabilities of O2 and 2 gases through the polymer liquid crystalline membranes were measured by the volumetric method. Molecular motions of the liquid crystalline polymers were investigated by the dynamic spring analysis method, which was effective for the characterization of the liquid crystalline polymers above the glass transition temperature. In the case of the liquid crystalline polymers with the side chain mesogenic group, it was proved that the polarity difference at the end group of the mesogenic side chain influenced the dynamic viscoelastic properties, molecular aggregation structure and gas permeation properties. The temperature dependence of gas permeation shows a breaking point at the phase transition temperature range. Therefore, it is apparent that the liquid crystalline polymer membranes exhibited gas permeation behavior similar to that of the polymer/liquid crystal composite membrane, which was reported previously.View full abstractDownload PDF (1795K) -
Kikuo SHOJI, Yukio NAKAMURA, Eiichi UEDA, Masatami TAKEDA1986 Volume 43 Issue 5 Pages 295-299
Published: May 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSDifferential scanning calorimetry and dilatometry were not useful to determine the correct glass transition temperature (Tg) of cholesteryl methacrylate and butyl methacrylate copolymers, because of poor reproducibility. This study shows that reproducible values of Tg of copolymer can be determined by gas chromatography from retention diagrams of alkalne for copolymers, and that differences in molecular arrangement of liquid crystalline polymer can be reflected in the changes in the mole fraction activity coefficients, which changed remarkably after the thermal treatment of copolymers.View full abstractDownload PDF (849K) -
Ryo OHTA, Yasuyuki KANAI, Keisuke FUNAKI, Junichi AMANO, Seiji UJIIE, ...1986 Volume 43 Issue 5 Pages 301-306
Published: May 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSSemi-flexible polyesters made of 4, 4′-dioxyazo- or 4, 4′-dioxyazoxy-benzene mesogenic unit with α, ω-alkanedioyl spacer readily form a liquid crystalline phase, in contrast to the polyesters of 4, 4′-dioylazo- or 4, 4′-dioylazoxy-benzene with α, ω-alkanedioxy spacer. Reverse order of the ester-linkage between mesogenic unit and spacer affects the formation of liquid crystalline phase in a striking manner.
The introduction of chiral unit into the alkyl spacer givès a cholesteric phase, and the cholesteric pitch varies with the composition of spacer group.
Compared with the polyesters having alkyl spacer, polycarbonates containing oxyethylene sequences in the spacer group have an extremely low transition temeprature to the nematic state. This would originate from the flexibility of oxyethylene unit.View full abstractDownload PDF (1795K) -
Toshiyuki URYU, Takashi KATO1986 Volume 43 Issue 5 Pages 307-310
Published: May 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSEffects of thermal history of heating and cooling cycles on thermal behavior of a thermotropic liquid crystalline polyester containing alkyl spacer were investigated by DSC. The DSC scanning was performed between 60°C and 310°C at rates of 20°C/min under dry nitrogen. Multiple melting endotherms were observed for the heating cycle. Enthalpies of each peak changed during the repetition of heating and cooling cycles. New endotherm peak appeared at higher temperature and its intensity increased up to 7th heating cycle. Microscope observation on the second heating cycle showed thatthe polyester became fluid at 226°C. But fluidity was observed at 242°C on the 10th heating cycle. The temperature of the nematicisotropic transition rose as heating and cooling cycles were repeated. Inherent viscosity increased as heating and cooling cycles were repeated. These changes of phase transition behavior were caused by increasing of molecular weight and by changes of crystalline form through the DSC scanning cycles.View full abstractDownload PDF (561K) -
Mamoru TANAKA, Tadao NAKAYA1986 Volume 43 Issue 5 Pages 311-314
Published: May 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSPolyurethanes were synthesized by the reaction of 4, 4′-di (2-hydroxymethyloxy) biphenyl with diisocyanates such as hexamethylene diisocyanate (HDI), dicyclohexylmethane 4, 4′-diisocyanate (H12MDI), cyclohexane 1, 3-di (methylisocyanate) (H6XDI), 2, 4-tolylene diisocyanate (TDI), and 4, 4′-diphenylmethane dissocyanate in DMF for 1.5hr at 100-140°C in the absence of catalysts. The polyurethanes obtained from HDI, H12MDI, H6XDI and TDI exhibited mesomorphic phase at 188-203°C, 147-172°C, 135-193°C and 151-193°C, respectively.View full abstractDownload PDF (562K) -
Kaoru SHIBATA, Seiji ARITA, Junkichi SOHMA1986 Volume 43 Issue 5 Pages 315-317
Published: May 25, 1986
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSESR spectra of vanadyl complexes in Knafji residue were measured in the temperature range 20-420°C. Each complex has a typically axially anisotropic structure at room temperature. The spectra became completely isotropic above 385°C, and the rotational correlation time τc of the vanadyl complexes was estimated. Up to 400°Cτc decreased with increasing temperature, but beyond 400°C it began to increase with increasing temperature. Based on this contradiction between the temperature dependence ofτc and that of the viscosity, the formation of a carbonaceous mesophase embryo is discussed. The apparent activation energy for the formation of the embryo was estimated to be 39 kcal/mol from the Arrhenius plot of the rate constant.View full abstractDownload PDF (516K)
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