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The Effects of Folding on High Strength Fibers Used in Soft Body Armor



Haruki Kobayashi, Walter G. McDonough, Joy Dunkers, Jae H. Kim, Hae-Jeong Lee, Scott Wight, Amanda L. Forster, Kirk D. Rice, Gale A. Holmes


Poly (p-phenylene benzobisoxazole) (PBO) fibers have been used in soft body armor (SBA) because of their high mechanical strength. However, there was an unexpected failure of a first responder's SBA which was composed of PBO fiber that was in service for only a few months. As folding during use may be a possible reason for mechanical property degradation, the effects of folding on the mechanical properties and structures of PBO and poly (p-phenylene terephthalamide) (PPTA) fibers were investigated. PBO fibers showed significant mechanical property degradation whereas PPTA fibers effectively maintained their mechanical strength. Structural changes in PBO fibers were detected using the small angle x-ray scattering (SAXS) technique. Reinforcing the results from SAXS, confocal microscopy showed extensive kink banding in the PBO fibers but no signs of internal damage in the PPTA fibers. Interestingly, no surface damage was seen in either PBO or PPTA fibers when they were examined using environmental scanning electron microscopy.
Proceedings Title
Asian Protective Clothing Conference 2011
Conference Dates
December 6-8, 2011
Conference Location
Nagano, JP


ballistics, polymers


Kobayashi, H. , McDonough, W. , Dunkers, J. , Kim, J. , Lee, H. , Wight, S. , Forster, A. , Rice, K. and Holmes, G. (2012), The Effects of Folding on High Strength Fibers Used in Soft Body Armor, Asian Protective Clothing Conference 2011, Nagano, JP (Accessed April 17, 2024)
Created January 22, 2012, Updated October 12, 2021