Crystallization morphology and crystallization kinetics of a liquid crystalline polyimide

Abstract

Crystallization morphology and crystallization kinetics of an aromatic thermotropic liquid crystalline polyimide, synthesized from 1,2,4,5-benzenetetra-carboxylic dianhydride (PMDA) and 1,3-bis[4-(4′-aminophenoxy) cumyl)] benzene (BACB), were studied by means of polarized light microscopy and differential scanning calorimetry. Isothermal crystallization experiments were performed at both isotropic temperatures and non-isotropic temperatures. Popoff and hedgehog types of negative spherulites with lamellar structure and needle-like positive crystals grown from the isotropic melt have been observed; Negative loose spherulites without lamellar structure were observed from the mesophase. The spherulites growth rates at different temperatures were measured. Isothermal crystallization kinetics for different transitions were studied by using Avrami equation.