侧链液晶环氧树脂及其固化物的研究

本文以联苯单酚为介晶基元合成了单官能团环氧树脂，再与双酚A型环氧树脂和二元胺交联聚合制备了侧链型的液晶环氧网络材料，保持了较好的液晶织态。     

液晶环氧树脂改性普通环氧树脂的研究

合成了一种液晶环氧树脂,并使之与普通环氧树脂共混固化,共混固化物的力学性能和热稳定性比普通环氧树脂固化物有明显的提高。     

侧链型脂环族环氧树脂合成与应用

侧链型脂环族环氧树脂具有粘度低,电气绝缘性,机械性能好,耐大气老化等特点,具有广阔的应用前景。简介发其发展状况,性能特点,重点介绍了主要产品的制备方法及应用领域。     

热致液晶聚合物共混改性PC的研究进展

综述了近几年来热致性液晶聚合物(TLCP)与聚碳酸酯(PC)共混改性方面的研究进展，以及TLCP的加入对PC的熔融和结晶行为、粘度、形态结构以及力学性能的影响，并阐述了增容技术在共混改性中的重要性。     

热致性液晶聚合物改性环氧树脂的研究进展

本文介绍了热致性液晶聚合物的结构、性能及其应用,在理论上阐述了热致性液晶聚合物改型环氧树脂的机理,介绍了国内热致性液晶聚合物改性环氧树脂的研究进展。     

热致液晶聚合物共混改性聚酰胺的研究进展

综述了近几年来热致性液晶聚合物(TLCP)与聚酰胺(PA)共混改性的研究进展,以及TLCP的加入对PA的熔融和结晶行为、粘度、形态结构以及力学性能方面的影响,并阐述了增容技术在共混改性中的重要性。     

芳香型聚氨酯改性环氧树脂共混材料的研究

以芳香型二元醇为原料，用原位聚合的方法制备了环氧树脂／芳香型聚氨酯共混材料。用红外光谱表征了其反应，测试了所得材料的力学性能，用热失重和差示扫描量热法对所得材料进行了热性能研究。结果表明，用芳香型聚氨酯改性环氧树脂，既能提高环氧树脂的韧性，也能提高环氧树脂的力学性能与热性能。     

液晶聚合物的研究进展

综述了近年来液晶聚合物的研究状况和合成技术进展,重点讨论了主链型液晶聚合物、侧链型液晶聚合物及甲壳型液晶聚合物的分子结构设计、合成方法及主要性能。同时对液晶聚合物的发展趋势及应用前景进行了分析和展望。     

液晶相对分子质量对热致性液晶／环氧树脂共混物性能的影响

采用自行合成的各种相对分子质量的反应型液晶聚合物（LCPU）对环氧树脂CYD-128/4，4′-二氨基二苯砜（DDS）固化体系进行改性，固定LCPU用量为5%，对各种改性体系的冲击强度，拉伸强度，弯曲强度，弹性模量，玻璃化转变温度（Tg），热失重温度（Td）、电性能，吸水性能与LCPU相对分子质量（n）的关系进行了研究，结果表明，LCPU的相对分子质量对固化物的力学性能和热性能影响较大，对其电性能和吸水性能的影响较小，当n=6时LCPU对环氧树脂的综合改性效果最好。     

环氧树脂共混改性及其发展趋势

综述了环氧树脂共混改性的主要方法及最新进展,对环氧树脂互穿网络聚合物(IPN)和热致液晶聚合物(TLCP)改性环氧树脂的前景进行了分析。     

丙烯酸酯液体橡胶改性环氧树脂胶粘剂的研究

以侧链含环氧基团的丙烯酸酯液体橡胶为改性剂 ,二乙撑三胺基甘油正丁基醚为固化剂制备了一种室温固化环氧树脂胶粘剂。重点研究了其粘接工艺性、力学性能和丙烯酸酯液体橡胶的改性作用。研究结果表明 :该胶粘剂具有较好的粘接工艺性能和拉剪强度 ,加入丙烯酸酯液体橡胶后拉伸剪切强度有显著的提高 ;液体橡胶环氧基含量和橡胶添加量对胶粘剂拉剪强度有重要的影响 ,每百份环氧树脂加 10份环氧基含量为 1.2mmol·g-1的丙烯酸酯液体橡胶 ,铝合金胶接试片拉剪强度提高了 133% ,复合材料胶接试片拉剪强度提高了 12 4 % ,4 5 # 钢胶接试片拉剪强度提高了 84 %。     

Modification of an o‐cresol formaldehyde epoxy resin by the thermotropic liquid crystalline polymer

Two novel liquid crystalline polymers, polydiethyleneglycol bis(4‐hydroxybenzoate) terephthaloyl and block copolymer (PDBH), were synthesized by condensation reaction. The blends of the two liquid crystalline polymers and o‐cresol formaldehyde epoxy resin were prepared by linear phenol‐formaldehyde resin as curing reagent. Both mechanical and thermal properties of the blends containing liquid crystalline polymer were improved to a certain extent. By adding 5 wt % PDBH, the impact strength, bending strength, and the glass transition temperature were enhanced by 128%, 23.84%, and 28°C, respectively, compared with the unmodified version. The results of curing kinetics showed that the curing reaction active energy of the modified system by PDBH decreased from 79.70 to 70.26 kJ/mol. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1626–1631, 2005     

Synthesis and thermal properties of combined liquid crystalline epoxy resins

Liquid crystalline epoxy resins were prepared by the curing reaction of epoxy and amine compounds with a mesogenic group in the mesomorphic temperature range. Some epoxy resins exhibited a typical liquid crystalline phase. Curing reaction of a mesogenic epoxy compound with an aliphatic amine compound containing cyano biphenyl group was faster than that of another epoxy resins confirmed by thermally controlled Fourier transform infrared measurements. The glass transition temperature of the liquid crystalline epoxy resin containing cyano biphenyl group increased with increasing curing reaction time. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1979–1990, 1998     

Bistable light scattering effects in a (side chain liquid crystalline polymer)/(low molecular weight liquid crystal) composite and in a ferroelectric liquid crystalline polymer

The electro-optical effects and aggregation states of liquid crystalline polymer (LCP)/ low molecular weight liquid crystal (LC) composite and ferroelectric liquid crystalline copolymer (FLCP) have been investigated. The nematic LCP was observed to be miscible with the nematic LC over wide ranges of concentration and temperature. The binary mixture showed an induced smectic phase in the range of 80/20-20/80 mol%. The electro-optical effects of the LCP/LC composite in an induced smectic phase could be classified into the turbid (light- scattering) and the transparent states upon application of AC and DC electric fields, respectively. The transient scattering mode was obtained by repeated voltage polarity reversal in the chiral smectic C phase of FLCP. The reversible transparent-opaque (light scattering) change was observed in the chiral smectic C state upon application of DC and AC electric fields, respectively. Both transparent and light-scattering states of the LCP/LC composite and the FLCP could be maintained, even after the electric field had been turned off (memory effect). The bistable effects of LCP/LC composite and FLCP are opposite under the same conditions. A novel type of electro-optical effect on light scattering was obtained for liquid crystalline polymer in the smectic states.     

The effect of mesogenic length on the curing behavior and properties of liquid crystalline epoxy resins

The effect of mesogenic structure on the properties of liquid crystalline epoxy (LCE) resins was investigated. The mesogenic lenght of the LCE was changed by changing the length of the rigid rod unit of LCE and it was correlated with the curing behavior and thermomechanical properties of LCE resins. The curing of LCE resins was accelerated in the LCE with LC phase during curing and storage modulus and glass transition temperature of LCE thermosets were high in the epoxy networks with long mesogenic group. In addition, the LC phase of LCE was stable for LCE with long mesogenic group and it was maintained until decomposition.     

Multilayer coextrusion of rheologically modified main chain liquid crystalline polymers and resulting orientational order

Liquid crystalline polymers (LCP) are attractive candidates for use as barrier films in packaging and high performance membrane applications due to their extraordinary barrier properties and chemical resistance. However, LCPs usually display extremely low viscosities, which makes processing them into multilayer films using coextrusion a challenge due to the mismatch of their viscosities with other film components. In this study, a commercial grade diepoxy reagent (Heloxy 67) was used to modify the rheological properties of a thermotropic main chain LCP. The effects of diepoxy concentration and reaction time on the melt viscosity and liquid crystal structures of the LCP were investigated. The addition of small amounts of diepoxy (e.g., 1.5 wt. %) increased the viscosity of the LCP nearly 15-fold. However, addition of excessive diepoxy (e.g., 2 wt. % or greater) led to cross-linking of the LCP. More importantly, these modified samples were thermally stable when melt reprocessed at temperatures of up to 250 °C in air. High quality multilayer films were prepared by coextruding the rheologically modified LCP with polypropylene-graft-maleic anhydride. The orientational order of the LCP in the multilayer films was studied by polarized infrared spectroscopy as well as x-ray diffraction. Interestingly, instead of aligning along the shear direction, the LCP chains tended to orient perpendicular to the extrusion direction, presumably due to a ‘log-rolling’ effect during processing.     

Polycarbonate/liquid crystalline polymer blend: Crystallization of polycarbonate

The enhanced crystallization of polycarbonate in the blend of liquid crystalline polymer/polycarbonate/(ethylene-methyl acrylate-glycidyl methacrylate) copolymer (LCP/PC/E-MA-GMA) was studied by wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The LCP/PC/E-MA-GMA 5/95/5 blends annealed at 200 °C, for 2, 4, 6, and 10 h, present an obvious crystalline structure corresponding to PC crystallization. The PC crystal obtained shows two melting temperature, T_m1 of about 214 °C and T_m2 of about 231 °C, with a total heat of fusion of 29 J/g (annealing time = 10 h). The preliminary results indicate that amorphous PC can be induced to crystallization by the synergistic action of LCP dispersed phase and reactive compatibilizer.     

Molecular orientation in quenched channel flow of a flow aligning main chain thermotropic liquid crystalline polymer

We report measurements of molecular orientation in solid specimens of a main-chain thermotropic liquid crystalline polymer (LCP) that were quenched from mixed shear-extensional channel flows. The polymer under investigation is a random copolyether with mesogens separated by flexible hydrocarbon spacers. This polymer is known to exhibit ‘flow aligning’ dynamics under slow shear flow. Experiments were designed to preserve the molecular orientation state, representative of steady, isothermal channel flow in the solid samples, so that comparisons could be made against in situ channel flow measurements on other main chain thermotropes without flexible spacers, including a commercial fully aromatic copolyster. In the flow aligning material, little change in orientation was found in slit-contraction flows, and only modest drops in orientation were found in slit-expansion flow. This contrasts strongly with data on commercial LCPs, suggesting that these materials may be of the ‘tumbling’ type.