Novel Fine Structures in Poly-p-phenylenebenzobisoxazole Fibers Induced by Water Vapor, Hot Water, and Non-Aqueous Coagulation II Random and Radial Preferential Orientations of the Crystal a-Axis

Abstract

The preferential orientation of the a-axes of poly-p-phenylenebenzobisoxazole (PBO) crystals in PBO fibers made with differential coagulation processes is characterized. Electron diffraction and micro-focus X-ray diffraction were carried out for this purpose. To estimate the alignment quantitatively a two-phase model is proposed and the calculated X-ray diffraction profiles fit well with the measured profiles. Water vapor coagulation at high temperature gave mostly almost random preferential orientation while a non-aqueous coagulation produced radial orientation. The fibers made with hot liquid water coagulation were characterized as a middle form between the limits of radial and random orientations.

Keywords:

• coagulation
• fiber structure
• micro-focus X-ray diffraction
• poly-p-phenylenebenzobisoxazole
• preferential orientation
• rigid-rod polymer

Acknowledgments

The present author express his sincerely gratitude to Dr. C. Riekel, Dr. M. Burghammer, and Dr. R. Davies at the ESRF ID13 beam line for micro-focus X-ray diffraction measurement. Professor K. Tashiro of Toyota Technological Institute gave the author useful comments on analysis of the micro-focus X-ray diffraction patterns, which should be well acknowledged. Professor R. J. Young at University of Manchester suggested some useful advice for publication. Thanks are also extended to Mr. K. Kiriyama and Mr. S. Watanuki for fiber preparation and Mr. Y. Shimizu for electron microscopy in Toyobo Co., Ltd.