Novel Fine Structures in Poly-p-phenylenebenzobisoxazole Fibers Induced by Water Vapor, Hot Water, and Non-Aqueous Coagulation I Molecular Orientation Along the Fiber Axis and Fine Structures

Abstract

This article is concerned with describing novel structural features of the water vapor coagulated Poly-p-phenylenebenzobisoxazole fiber in comparison with other PBO fibers made with hot liquid water and non-aqueous coagulation. Micro-focus X-ray diffraction was adopted to see the skin-core difference of molecular orientation and crystal size along the fiber-radius direction. Low temperature differential scanning calorimetry (DSC) was performed to elucidate the structural features of never-dried fibers made with the different coagulation techniques. Comparison of micro-focus X-ray diffraction profiles from the different positions on the fiber suggests less anisotropy of preferential orientation for the water vapor coagulated fiber. The fiber made through water vapor coagulation showed a large skin-core difference in molecular orientation with structural inhomogeneity along the fiber axis.

Keywords:

• fiber structure
• micro-focus X-ray diffraction
• PBO
• preferential orientation
• rigid-rod polymer

Acknowledgments

The present author expresses his sincere gratitude to Dr. C. Riekel, Dr. M. Burghammer and Dr. R. Davies at the ESRF ID13 beam line for the micro-focus X-ray diffraction measurement. SAXS measurements were made possible by the assistance of Professor K. Tashiro of Toyota Technological Institute. Thanks are extended to Mr. K. Kiriyama and Mr. S. Watanuki for fiber preparation in Toyobo Co., Ltd.