聚苯撑苯并二噻唑的甲基磺酸溶液的相转变过程及其动力学研究

用退偏振光强度法及偏光显微镜研究了溶致性液晶高分子聚苯撑苯并二噻唑的甲基磺酸溶液(PBT/MSA)由液晶相至各向同性相(N→I转变),及由各向同性相至液晶相(I→N转变)的相变过程.液晶相的形成(I→N)服从Av-rami方程,Avrami指数为1左右,表明该体系的液晶相是以一维棒状方式形成的.相转变温度与浓度有关,提高温度可加速在应力下液晶相长程有序结构的形成.

STUDY ON KINETICS AND PROCESS OF PHASE TRANSITIONS OF LYOTROPIC LIQUID CRYSTALLINE POLYMER PBZT/MSA

The phase transitions from nematic mesophase to isotropic state (N-I) and from isotropic state to nematic mesophase (I-N) of the poly (P-phenylene benzobisthiazole)-methyl sulfonic acid solution (PBZT/MSA) have been studied by depolarized light intensity and polarized microscopy.It was found that the phase transition temperature is a function of theconcentration of PBZT/MSA. The atructural long range order of PBZT/MSA induced by shearing can been enhanced by increasing temperature.The study of kinetics of I-N phase transition shows that the transition is nucleation controlled which can be described by an Avrami equation. The Avrami exponent is about 1 which suggests the nucleation is followed by rodlike growth.The results show that the depolarized light intensity is a simple and an effective method for study of the process and the kinetics of phase transitions of liquid crystalline polymers, especially for lyotropic liquid crystalline polymers.