一类可纺丝的全芳香热致性液晶共聚酯的合成和表征

利用Higashi芳香聚酯直接缩聚法的原理 ,采用一步混合投料直接缩聚的方法 ,以对羟基苯甲酸(PHB)、间苯二甲酸 (MPA)、4 ,4′ 二羟基二苯酮 (DHBP)和对苯二酚 (HQ)为单体原料 ,合成了全芳香共聚酯 .该合成方法反应条件温和 ,简单易控 ,产物分子量高 .用差热分析 (DSC)、热重分析 (TA)、偏光显微镜 (PLM)、广角X 射线衍射 (WAXD)等测试分析手段对共聚酯的热性能和液晶特性进行了表征 .研究结果表明 ,利用此方法合成所得的聚合物呈明显的向列型热致液晶特性 ,热稳定性高 ,并具有极易成纤的特点 ,有望成为一种可用于纺丝的全芳香热致液晶共聚酯材料

SYNTHESIS AND CHARACTERIZATION OF THERMOTROPIC LIQUID CRYSTALLINE AROMATIC POLYESTERS WITH EXCELLENT FIBER-FORMING PROPERTY

A series of all-aromatic polyesters with high molecular weight derived from m-phthalic acid,4,4′-dihydroxybenzophenone,hydroquinone,and p-hydroxybenzoic acid were synthesized by direct polycondensation method in sulfonyl chloride (BsCl),dimethylforamide (DMF) and pyridine (Py) at various bisphenols ratios.The liquid crystalline behaviors and thermal properties of the all-aromatic polyesters have been characterized by polarized light microscopy (PLM),wide angle X-ray diffraction (WAXD),thermogravimetric analysis and differential scanning calorimetry (DSC).The results show that the all-aromatic polyesters with high molecular weight can be synthesized in an easily controlled mild condition as compared with the usual ester exchange reaction.Under polarizing optical microscope,all the synthesized polyesters with different ratios of bisphenols show a very high degree of birefringence with threaded nematic texture in the molten state and strip texture after shearing from the melt.Comparing the polyesters with those synthesized by melt ester exchange reaction,the polyesters have a good crystallinity from the result of WAXD studies.All the polymers show high thermal stability and the decomposition temperature range for 5% weight loss is from 427℃ to 476℃,but there is no significant difference between their temperature of maximum decomposition.The results of DSC show that the glass transition can not be obtained in the first heating process,and can be observed in the cooling and second heating processes.In the first heating run,there exist two evident endothermal transitions in ca. 200℃ and 270℃,and in the second run,only one in ca. 270℃.The polyesters have excellent fiber-forming capability with a potential for melt spinning.