Toshihide Inoue

New types of liquid crystalline epoxy resins cured by a mesogenic hardening compound

Abstract The new epoxy resins, EPD-CAA10 and EPTB-CAA10, were synthesized by reacting stoichiometrically the diepoxides, 4,4′-bis(2,3-epoxypropoxy)bisphenol A (EPB) and 4,4′-bis-2,3-epoxypropoxy)-3,3′,5,5′-tetramethylbiphenol (EPTB), respectively, with a mesogenic hardening compound, 4,4′-bis(ω-carboxydecanoxy)azoxybenzene (CAA10), using tri-n-butylamine as a catalyst. The reaction procedures and the mesogenic phase transitions for the two epoxy resins were studied by the use of infra-red (i.r.), spectroscopy, differential scanning calorimetry (d.s.c.) polarizing microscopy and X-ray diffraction spectroscopy. It was found that both of the differential EPB-CAA10 and EPTB-CAA10 systems had a mesophase which was functionalized by the mesogenic hardening compound; EPB-CAA10 showed a smectic-like mesophase between 70 and 90°C when the polymer was not gelated but had no mesophase when gelated, while EPTB-CAA10 also had a smectic-like mesophase when not gelated, but showed a nematic phase when gelated.

Thermotropic Polyarylates Derived from Substituted Hydroquinones and 4,4′-Diphenyldicarboxylic Acid

Abstract As-spun fibers of poly(methylhydroquinone 4,4′-diphenyldicarboxylate) (Me-HQ/BB) exhibited a lower modulus than poly(phenylhydroquinone 4,4′-diphenyldicarboxylate) (Ph-HQ/BB) and poly(2-chlorophenylhydroquinone 4,4′-diphenyldicarboxylate) (CP-HQ/BB) due to the lower degree of elongational flow orientation and the lower value of orientation function of the nematic domains (F). However, injection molded specimens of Me-HQ/BB exhibited a higher flexural modulus than Ph-HQ/BB and CP-HQ/BB due to the higher packing density of the polymer chain. Thus, the packing density of polymer chain is a more influential factor than the F value to achieve a high modulus of injection molded specimens.

Future directions for the research and development of polyesters: From high-performance to environmentally friendly

We discuss the future directions for the research and development of polyester-based materials. In the discussion of polyesters as industrial materials, one direction is the development of high-performance materials. Poly(ethylene terephthalate) (PET), known as one of the most important polyesters, was developed early in the 1940s. We discuss two approaches to the development of high-performance materials suitable for injection-molding applications using PET units. The first approach is development of high-performance materials by copolymerization with bibenzoic acid (BB), which has a rigid structure, and the second approach is development of liquid-crystal polyesters (LCPs) with superior thermal resistance and excellent flowability using PET units. The other future direction for research and development is the targeting of environmentally friendly materials. Poly(lactic acid) (PLA), derived from bio-based materials, is a very important material because it can realize the carbon neutral cycles. Nevertheless, the practical properties of PLA itself are unsatisfactory compared to other plastics derived from fossil resources. We have developed PLA-based polymer alloys with various practical properties by utilizing a newly developed nanoalloy technology.

Thermotropic Liquid Crystalline Polyarylates

Recently thermotropic liquid crystalline polyarylates (TLCPs) have been attracting much attention because of their very high modulus, excellent processability, thermal resistance, dimentional stability, flame resistance and chemical resistance, and the possibility of being a substitute for Al. However, TLCPs have also some serious problems such as mechanical anisotropy, low weldline strength and fibrization (delamination), and the modulus is still lower than that of Al. We have been working on the preparation of novel TLCPs with higher weldline strength and resistance to fibrization and found that TLCPs derived from 4,4′-diphenyldicarboxylic acid(BB) would be promising materials as a substitute for Al.

Liquid Crystalline Epoxy Resins Consisting of Mesogenic Diepoxide and Mesogenic Hardner

Abstract Two liquid crystalline (LC) epoxy resins consisting of LC diepoxide and LC hardner were synthesized, diglycidyloxyazoxybenzene (DGA), 4,4′-bis (ω-carboxy decanoxy) azoxybenzene (CAA10) and DGA with 4, 4′-bis (ω-hydroxy undecanoxy) azoxybenzene (HAA11), and their reaction mechanism, mesomorphic phase transition and thermal expansion were investigated by use of DSC, IR, polarized microscopy, X-ray diffractometry and capillary dilatometry. The fully gelated DGA-CAA10 formed a network structure in which one interchain crosslink was made per 5.6 repeating unit, and showed no mesophase. The DGA-HAA11 of linear typed polymer showed a smectic A phase when not fully cured, while a namatic phase when gelated. It was pointed out that the mesogenicity of epoxy resin is governed by the mesogenicity of monomers but is also correlated with the crosslinking density and degree of polymerization. In the fully gelated DGA-CAA10, thermal expansion coefficient (α) was about 2.2 × 10−4 °C−1 below Tg and 3.4 × 10−4 °C−...

Thermotropic polyarylates derived from substituted hydroquinones and p-terphenyl-4,4″-dicarboxylic acid

Abstract Polyarylates from substituted hydroquinones (HQs) and p -terphenyl-4,4″-dicarboxylic acid (TPDA) that were modified with 1,2-bis(phenoxy)ethane-4,4′-dicarboxylic acid (PEC), 1,2-bis(2-chlorophenoxy)ethane-4,4′-dicarboxylic acid (ClPEC), terephthalic acid (TA) and p -hydroxybenzoic acid (HBA) were prepared and their thermal and mechanical properties were investigated. These polyarylates exhibited liquid crystallinity at about the same temperatures as polyarylates derived from substituted HQs and 4,4′-diphenyldicarboxylic acid (BB). However, as-spun fibers and injection-molded specimens of these polyarylates exhibited lower moduli than those of substituted HQs and BB that were modified with PEC, Cl-PEC and TA.

Model compounds for high modulus aromatic polyether-esters. X-ray structures and energy calculations of dimethyl 1,2-bis(phenoxy)ethane-4,4′-dicarboxylate and its chlorinated derivatives

The determination of the conformation of molecular chains and modes of packing of poly[ethylene-1,2-bis(phenoxy)ethane-4,4′-dicarboxylate] and its chlorinated derivatives is assisted by the X-ray crystallographic analysis and energy calculations of three model compounds. Molecules of dimethyl 1,2-bis(phenoxy)ethane-4,4′-dicarboxylate are packed in an orthorhombic crystal system, space group Pbca, with a = 6.374(4)A, b = 35.094(6) A, c = 7.124(5) A, and z = 4. The molecule has a crytallographic centre of symmetry at the centre of the CH2-CH2 bond and the two ether O atoms are oriented anti to each other. Molecules of dimethyl 1,2-bis(2-chlorophenoxy)ethane-4,4′-dicarboxylate are packed in a monoclinic crystal system, space group C2c, with a = 12.712(2) A, b = 7.594(1) A, c = 18.709(2) A, β = 100.06(1)°, and z = 4. The molecule has a crystallographic two-fold axis at the centre of the CH2-CH2 bond and the O-CH2-CH2-O torsion angle of 69.9° makes the conformation of this part of the molecule gauche. Molecules of dimethyl 1,2-bis(2,6-dichlorophenoxy)ethane-4,4′-dicarboxylate are packed in a monoclinic crystal system, space group P21n, with a = 4.041(2) A, b = 12.799(1) A, c = 18.8528(9) A, β = 91.36(1)° and z = 2. The molecule has a crystallographic centre of symmetry at the centre of the CH2-CH2 bond and the two ether O atoms are oriented anti to each other. CH2-CH2 bond shortenings were observed in the three model compounds. The crystal structures were compared with energy-minimized molecular structures using the semi-empirical quantum-mechanical method MNDO, giving results in substantial agreement.

Thermal properties and flame retardancy of brominated polyether-esters.

ポリアルキレン1, 2-ビス (2, 6-ジブロモフェノキシ) エタン-4,4′-ジカルボキシラート (ポリエーテルエステル) の熱的特性を調べた. このポリエーテルーエステルのガラス転移温度は, ポリアルキレン1, 2-ビス (2-ブロモフェノキシ) エタン-4,4′-ジカルボキシラートよりも高くなった. ポリエチレン1, 2-ビス (2, 6-ジブロモフェノキシ) エタンは, 臭素含量が49.7%と高くポリブチレンテレフタラート (PBT) 樹脂などの難燃剤として使用できることがわかった. また, 1, 2-ビス (2-ブロモフェノキシ) エタン-4,4′-ジカルボン酸を共重合またはポリエチレン1, 2-ビス (2-ブロモフェノキシ) エタン-4,4′-ジカルボキシラートをブレンドしたポリエチレンテレフタラート (PET) 繊維 (臭素含量10%) は, 自己消化性であり, ヤング率はPETよりも高く, 耐光性はヘキサブロモベンゼンをブレンドしたPET繊維 (臭素含量10%) よりも優れていることがわかった.