Microstructures and their orientation behavior in a thermotropic polyester

Abstract

Microstructures and their orientation behavior in quenched films of a thermotropic polyester, poly(chloro-1,4-phenylene-trans-1,4-cyclohexanedicarboxylate), were studied by electron microscopy, polarized-light microscopy, and x-ray diffraction. Oriented films were obtained by shearing the anisotropic melt of the polymer and cooling to 0°C. Fibrous structures shaped like ribbons or prisms were observed in fractured lateral surfaces of quenched films. Prismlike fibrils are composed of ribbonlike fibrils, the thickness of which is less than 0.1 μm. Streaks suggesting the end of ribbonlike fibrils were observed on the surface of fibrils. The fibrils occur almost parallel to the direction of orientation of films. In the case of a poorly oriented film, the direction of orientation of the fibrils alters in waves. The period of the waves becomes longer with increasing degree of orientation. Bandlike structures 50–100 nm in width were observed on the surfaces of the films. They are arranged almost perpendicular to the direction of orientation of the films. The features of the microstructures observed in the wavelike fractured lateral surfaces of the thermotropic polyester film are schematically represented.