Degradation of Ballisitc Fibers


Eun Su Park, Charles M. Guttman, Gale A. Holmes, Kathleen Flynn, William Wallace


Polymers Division, MSEL, NIST



There is a great interest in the degradation of ballistic fibers to sunlight and high humidity, since it directly affects the lives of people who use protective ballistic armors.  Polybenzoxazole (PBO) fiber is one of ballistic fibers that have an excellent strength, modulus, high thermal stability and chemical resistance.  It’s relatively low density compared to other rigid-rod polymers such as Kevlar and M5, is useful when light weight is at a premium as in protective garments, and personnel ballistic armors.  However, to date, no mechanism has been shown to explain how these fibers degraded in the presence of sunlight or humid.  Recently, it was suggested that residual phosphoric acid left during the processing of PBO fibers combining with humid environments, sunlight and oxygen promote degradation.  No experiment has been done yet to test this.

In this study, we are trying to test the hypotheses by seeking evidence of phosphoric residues from the PBO fiber.  We use matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF MS) in order to confirm that the phosphoric acid incorporated in PBO fiber.  We also synthesize PBO oligomer with polyphosphoric acid following the commercial synthetic method.  Using MALDI-TOF MS, we analyze the end group distribution of PBO compound before and after hydrolytic and UV degradation.



Author information:

Eun Su Park

Guest Researcher

Mentor: Charles M. Guttman


Polymers Division

Materials science and Engineering Laboratory

National Institute of Standards and Technology

100 Bureau Drive, MS 8541

Gaithersburg, MD 20899-8541, USA

Building 224, Room B330

Tel: (301) 975-6790

Fax: (301) 975-3928



Category: Materials