CRYSTALLIZATION KINETICS OF THERMOTROPIC LIQUID-CRYSTALLINE POLY(ESTER-IMIDE)S

A thermotropic liquid crystalline poly(ester-imide) was synthesized fr om trimellitic anhydride, 5-aminovaleric acid and 2,6-dihydroxynaphtha lene by the melt polymerization. The isothermal crystallization kineti cs of the thermotropic liquid crystalline poly(ester-imide) was studie d by using DSC in temperature range 190-240 degrees C. Crystallization occurs in two stages (a fast crystallization process and a slow cryst allization process), leading to different levels of perfection and cry stal sizes. The apparent Avrami exponent has the low values of 0.11-0. 98, which represents a highly restricted one-dimensional (fibrillar) c rystal growth. It tends to be depressed because the high ordered molec ules (crystals) will prevent a polymer chain from the translational mo tion along the chain axis and the matching of crystallizable sequences with other chains. The fast crystallization process produces the rela tively ordered crystals and the slow crystallization generates the les s ordered crystals. WAXD shows that the dual endothermic peaks are rel ated to the existence of two different crystal sizes. (C) 1997 Elsevie r Science Ltd.