There is great interest in the degradation of ballistic fibers from exposure to sunlight and high humidity, because it directly affects the lives of people who use protective ballistic armor. However, to date, no mechanism has been found to explain how these fibers degrade in the presence of sunlight or humidity. Recently, it was suggested that residual phosphoric acid left during the processing of poly[(benzo [1,2-d:5,4-d ]-benzoxazole-2,6-diyl)-1,4-phenylene] (PBO) fibers promotes degradation, but there is no experimental evidence to support this hypothesis. In this study, we tried to identify residual phosphoric acid in PBO fibers in an effort to understand the failure of PBO fibers from a chemical degradation point of view. According to the results of X-ray fluorescence, gas chromatography/mass spectrometry, and matrix assisted laser desorption/ionization time-of-flight mass spectrometry data, PBO fibers contain excess phosphorous, which was not extracted by Soxhlet extraction. PBO model oligomers showed that phosphate ester linked compounds could be present in fibers after the elimination of acids by Soxhlet extraction.
Citation: Analytical Chemistry
Pub Type: Journals
Ballistic fiber, Phosphoric acid, Polybenzoxazole, X-ray fluorescence, Gas chromatography/mass spectrometry