固相聚合对萘环液晶聚芳酯结构与性能的影响  

Influence of solid-state polymerization on structure and properties of naphthalene ring structure aromatic liquid crystal copolyester

作　　者：魏朋 李志强[1] 李娇娇[1] 李俊慧 刘东 耿嘉骏 WEI Peng;LI Zhiqiang;LI Jiaojiao;LI Junhui;LIU Dong;GENG Jiajun(College of Intelligent Textile and Fabric Electronics,Zhongyuan University of Technology,Zhengzhou,Henan 450007,China;Collaborative Innovation Center of Advanced Textile Equipment and Technology by MOE and Henan Provincial Government,Zhengzhou,Henan 450007,China)

机构地区：[1]中原工学院智能纺织与织物电子学院,河南郑州450007 [2]先进纺织装备技术省部共建协同创新中心,河南郑州450007

出　　处：《纺织学报》2024年第9期50-55,共6页Journal of Textile Research

基　　金：国家自然科学基金项目(51803246);河南省高校科技创新人才支持计划资助项目(22HASTIT032);河南省高等学校青年骨干教师培养计划项目(2020GGJS140);中原工学院基本科研业务费专项资金资助项目(K2020YY005)。

摘　　要：为解决液晶聚芳酯熔融缩聚反应后期由于反应温度和熔体黏度过高导致的降解交联副反应以及成形加工困难等问题,以6-羟基-2-萘甲酸(HNA)、2,6-萘二羧酸(NDA)、对苯二甲酸(TA)、4,4'-二羟基联苯(BP)为原料,采用原位一锅熔融聚合法制备了低分子量萘环热致液晶聚芳酯,并对其进行固相聚合。通过差示扫描量热仪、热重分析仪、偏光显微镜、X射线衍射和熔融指数仪对固相聚合后的液晶聚芳酯结构与性能进行了测试。结果表明,液晶聚芳酯的熔融温度和结晶度受聚合时间和温度的影响较大,呈现出先增加后降低的变化趋势,但并不会改变聚芳酯的晶体结构,同样属于正交晶型。此外,固相聚合在温度305℃下反应12 h,液晶聚芳酯热学和结晶性能得到明显改善;高于此时间和温度时聚芳酯的熔点开始降低,热降解反应开始进行,热稳定性和结晶性能下降。Objective Degradation,cross-link side reaction and poor processing ability are caused by high reaction temperature and melt viscosity of liquid crystal copolyesters in the final stage of melt polycondensation.In order to solve such problems,low molecular weight of liquid crystal copolyesters was prepared by one-pot melting transesterification method.The influences of solid-state polymerization time and temperature on thermal properties,crystallization properties and melt index of liquid crystal copolyesters were investigated.Method In this study,the low molecular weight liquid crystal copolyester derived from 6-hydroxy-2-naphthalene carboxylic acid(HNA),2,6-naphthalene dicarboxylic acid(NDA),terephthalic acid,4,4'-dihydroxy biphenyl(BP)were prepared by in-situ one-pot melt polymerization method.After solid-state polymerization,the structure and properties of liquid crystal polyesters were analyzed by Differential scanning calorimeter,Thermogravimetric analyzer,polarized microscope,X-ray diffraction and melt index.Results The melting temperature of liquid crystal copolyester(T_(m))and the glass transition temperature(Tg)were found to increased and then decreased with the increase of polymerization time.Crystallization enthalpyΔHc and melting enthalpyΔH_(m) reached the maximum after 12 h of polymerization,and were decreased gradually with the increase of solid-state polymerization timeΔH_(c) andΔH_(m).Clear marble and textured liquid crystal texture were still observed 8 h after solid-state polymerization,showing nematic liquid crystal behavior,but with the increase of polymerization time,birefringence and texture gradually got blurred.When the polymerization time was increased to 36 h,the crystal structure did not change,remaining in the state of orthogonality.The results showed that the phase transition temperature and crystallization rate of liquid crystal copolyesters were greatly affected by polymerization time and temperature.The crystallization performance of liquid crystal copolyesters was better when t

关 键 词：热致液晶聚芳酯 熔融聚合 固相聚合 热学性能 晶体结构 

分 类 号：O632[理学—高分子化学] TS102[理学—化学]