Quiescent crystallization in thermotropic polyesters

Abstract

The crystallization event in a number of thermotropic polyesters containing hydroxybenzoic acid, naphthalene dicarboxylic acid, isophthalic acid, and hydroquinone has been followed by a variety of techniques including optical microscopy, calorimetry, and wide angle X-ray diffraction. The results indicate that massive structural rearrangements do not occur during crystallization and, hence, the structure of the crystal closely resembles that of the nematic melt. The Avrami plot gives an exponent of about 2 which suggests rod-like growth and is well within the range typical of semicrystalline polymers. Perhaps the most important point is that the standard techniques employed for gaining an understanding of the crystallization of semicrystalline polymers seem to give reasonable results on mesogenic polymers. Studies of quiescent crystallization on thermotropic systems can provide insight into the crystallization event in oriented flexible chain polymer melts.