Chemical and Physical Characterization of Poly(p-phenylene-2,6-benzobisoxazole) Fibers Used in Body Armor: Temperature and Humidity Aging

Published

November 1, 2006

Author(s)

Joannie W. Chin, E Byrd, Cyril Clerici, Amanda L. Forster, M Oudina, Li Piin Sung, Kirk D. Rice

Abstract

In recent years, poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers have become prominent in high strength applications such as body armor, ropes and cables, and recreational equipment. The objectives of this study were to expose woven PBO body armor panels to elevated temperature and moisture, and analyze the chemical, morphological and mechanical changes in PBO yarns extracted from the panels. A 30 % decrease in yarn tensile strength, which could be correlated to changes in the infrared peak absorbance of key functional groups in the PBO structure, were observed during the 26 week elevated temperature/elevated moisture aging period. Substantial changes in chemical structure were observed via infrared spectroscopy, as well as changes in polymer morphology observed using microscopy and neutron scattering. When the panels were removed to an ultra-dry environment for storage for 47 weeks, no further decreases in tensile strength degradation were observed. In a parallel study, fibers were sealed in argon-filled glass tubes and exposed to elevated temperature; less than a 4 % decrease in strength was observed after 30 weeks.

Citation

NIST Interagency/Internal Report (NISTIR) - 7373

Report Number

7373

NIST Pub Series

NIST Interagency/Internal Report (NISTIR)

Pub Type

NIST Pubs

Download Paper

https://doi.org/10.6028/NIST.IR.7373

Keywords

ATR, attenuated total reflectance (ATR), body armor, fiber, infrared (IR) spectroscopy, PBO, poly(p-phenylene-2, 6 benzobisoxazole)

Citation

Chin, J. , Byrd, E. , Clerici, C. , Forster, A. , Oudina, M. , Sung, L. and Rice, K. (2006), Chemical and Physical Characterization of Poly(p-phenylene-2,6-benzobisoxazole) Fibers Used in Body Armor: Temperature and Humidity Aging, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.IR.7373 (Accessed October 13, 2025)