序列嵌段共聚酯液晶高分子相转变动力学及机理研究

用DSC、PLM、WAXD等方法研究了序列嵌段共聚酯液晶高分子的结晶动力学及相转变机理.结果表明,从各向同性相温度(T_i)结晶经历了中介相阶段,从中介相温度(T_N)和从T_i温度结晶的结晶机理均为取向链段的聚集成核及低维生长,Avrami指数都接近2.两种结晶途径均形成了不同完善程度的结晶形态.柔性嵌段PTHF含量对试样的液晶行为和结晶行为有很大影响,PTHF含量在20％左右向列型中介相表现出高取向,易成核的特性.

CRYSTALLIZATION KINETICS AND MECHANISM OF PHASE TRANSITIONS FOR THERMOTROPIC SEQUENTIAL BLOCK COPOLYESTERS

The crystallization kinetics and mechanisms of phase transitions for sequential block copoly-mers synthesized through polycondensation of the mesogenic group 2-methyl-p-phenylene di(4-chloroformyl) benzoate, 1, 10-decanediol (B) and poly (oxytetramethylene) glycol (C) have been investigated by using DSC, PLM, and WAXD. As a feed ratio of B/C( 10/90, 20/80, 40/60, 50/ 50, wt%), the values of Avrami exponent are n≈2 at all the feed ratios. The crystallization from isotropic melt experienced the stage of mesophase period. The crystallization either from isorro-pic melt or from mesophase has the same mechanism including nucleation through aggregation of orientational segments and the two dimensional crystal growth. The flexible block of poly(oxyre-tramethylene)glycol has a significant influence on the structure formation. It is worth to indicate that ca. the ratio 20/80 there a lower Bk value and a larger entropy change △St during mesophase to isotropic melt transition.