The synthesis and modification of high performance thermotropic liquid crystal polyesters (TLCP) are still being investigated due to their excellent properties. In this study modification of poly(oxybenzoate-co-oxynaphthoate) (P-HBA/HNA), a random copolymer of 4-hydroxybenzoic acid (HBA) and 6-hydroxy-2-naphthoic acid (HNA), by 5 mol% of one of three AB type monomers (AB type monomers are those who have hydroxy and carboxylic end groups), vanillic acid (VA), 4-hydroxyphenylacetic acid (HPA) and 4-hydroxycinnamic acid (HCA), was conducted. The influence of the AB type third monomer on the liquid crystal properties, melting behavior, thermal stability, microstructure and fiber morphology of the resulting modified terpolyesters was comparatively studied relative to the parent copolymer. When 5 mol% of the HBA units were replaced, the resulting terpolyesters had much lower melting temperatures and could be easily melt processed, while the modified terpolyesters exhibited higher melting and glass transition temperatures when 5 mol% of the HNA units were replaced. Weaker melting peaks and larger melting ranges were observed for the modified terpolyesters, attributed to the existence of nonperiodic layer crystallites caused by the modifiers. The obtained terpolyesters showed good thermal stability and could be melt processed in a broad nematic phase temperature region. The molecular chain packing of the modified terpolyesters was almost destroyed by the third AB type reactants. Fibers prepared from the resulting terpolyesters exhibited well developed fibrillar structure and higher orientation factors, indicating that modification of the P-HBA/HNA by using the AB type monomers to improve its properties would be useful.

高性能热致液晶聚酯（TLCP）的合成和改性由于其优异的性能而仍在研究中。在这项研究中，对聚（羟基苯甲酸酯-共-羟基萘甲酸酯）（P-HBA / HNA）进行了修饰，将4-羟基苯甲酸（HBA）和6-羟基-2-萘甲酸（HNA）的无规共聚物以进行了三种AB型单体中的一种（AB型单体是具有羟基和羧基端基的那些），香草酸（VA），4-羟基苯基乙酸（HPA）和4-羟基肉桂酸（HCA）。相对于母体共聚物，比较研究了AB型第三单体对所得改性三元聚酯的液晶性能，熔融行为，热稳定性，微结构和纤维形态的影响。更换5摩尔％的HBA单元后，所得到的三元聚酯具有低得多的熔融温度并且可以容易地熔融加工，而当取代5mol％的HNA单元时，改性三元聚酯表现出较高的熔融和玻璃化转变温度。对于改性的三元聚酯，观察到较弱的熔融峰和较大的熔融范围，这归因于改性剂引起的非周期性层微晶的存在。所获得的三元聚酯显示出良好的热稳定性，并且可以在宽的向列相温度范围内熔融加工。改性的三元聚酯的分子链堆积几乎被第三种AB型反应物破坏。由所得的三元聚酯制备的纤维表现出良好的原纤维结构和较高的取向因子，