The Structure of Poly-2,5-Benzoxazole (ABPBO) and Poly-2,6-Benzothiazole (ABPBT) Fibers By X-Ray Diffraction
Abstract
The determination of the crystalline structure of oriented fibers of poly-2,5-benzoxazole (ABPBO) and poly-2,6-benzothiazole (ABPBT) is described. Both unit cells are metrically orthorhombic, with the parameters: a=6.06(17), b=3.384(13), c (fiber axis)=11.575(6) A for ABPBO, and a=6.044(6), b-3.47(7), c (fiber axis)=12.194(18)A for ABPBT. The fiber repeat consists in each structure of two fused ring groups arranged in a planar, zigzag conformation. The conformational torsion angle and orientation of chains within the unit cells are derived from a linked-atom least squares refinement technique. Polymer chains pack laterally through van der Waals interations. A plausible disorder model which involves defects in chain direction is presented. Refinement of a static disorder model for ABPBO in which fifty percent of the chains have their chain directions reversed leads to a lower R residual and sum of constraints. The determination of the crystal structures of these two polymers is important for understanding of the processing, properties and morphology of high strength, high modulus fibers of these materials. Keywords: Polybenzoxazole; Units; Cell; Aromatics; Heterocyclics; Polymers.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1985
- Accession Number
- ADA181695
Entities
People
- Albert V. Fratini
- Elisa M. Cross
- Joseph F. O'brien
- W. W. Adams
Organizations
- University of Dayton