全芳族热致液晶共聚酯的固态聚合

Solid State Polymerization of a Wholly Aromatic Thermotropic Liquid Crystalline Copolymer

采用固态聚合方法制备了一种由4-乙酰氧基苯甲酸(ABA)、6-乙酰氧基-2-萘甲酸(ANA)、对苯二甲酸(TA)和1,4-二乙酰氧基苯撑(HQA)合成的全芳族热致液晶共聚酯.通过偏光显微镜(PLM)研究了共聚酯的织态.测定了产物的熔点和比浓对数粘度.研究了固态聚合的实验条件,如反应时间、反应温度、氮气流量及粒子大小对共聚酯相对分子质量的影响.经固态聚合的液晶共聚酯样品在偏光显微镜下观察到典型的向列相条带织构.熔点和比浓对数粘度测量的结果表明,固态聚合过程中共聚酯相对分子质量大大提高.还讨论了不同实验条件下固态聚合的反应机理和反应速度.

Solid-state polymerization （SSP） has been applied for the synthesis of a wholly aromatic therrnotropic liquid crystalline copolyester derived from 4-acetoxybenzoic acid,6-acetoxy-2-naphthoic acid, hydroquinone diacetate and terephthalic acid. The texture of SSP products was observed by polarized light microscope （PLM）, and the molar mass of SSP products was characterized by differential scanning calorimeter （DSC） and viscosity measurement. The influence of various operating parameters,such as reaction time, reaction temperature, nitrogen gas flow velocity and particle size of the sampies,on SSP was investigated. It was found that the molar mass of the copolyester substantially increased during the SSP process,as shown by measurements of melting point and inherent viscosity of the products, and a typical nematic banded texture of the copolyesters with narrow bands was observed with PLM. The SSP reaction mechanism and rate were also discussed for SSP at various operating parameters.