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Description:
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The moisture absorption behavior of Zylon fibers was characterized in various high temperature and high humidity conditions in a controlled environment . The results of these thermal cycling tests show that PBO fibers not only absorb , but also retain moisture (approximately 0 .5 -3 % ) when exposed to elevated temperature and humidity cycles . Also , the impurities of Zylon fibers were characterized through the use of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA -ICP -MS ) and solid state Nuclear Magnetic Resonance (NMR ) . These tests demonstrated that , in addition to other impurities , PBO fibers may contain up to 0 .55 weight percent phosphorus , and that this phosphorus is present in the form of phosphoric acid . It was also shown through accelerated hydrolytic degradation tests that production procedures used to neutralize the acid present in the fibers have a beneficial effect on the hydrolytic performance of the fiber . The data collected in this study was then compared and contrasted to known Kevlar studies , identifying similarities , differences , and potential trends . The results of these tests seem to indicate that there is accelerated acid catalyzed hydrolysis occurring in the fiber which is causing these fibers to degrade at an increased rate . This condition is further accelerated by heat and humidity induced permanent fiber swelling . |