Vest yams

All vest yams were also compared to virgin PBO spool yam, manufactured in August 2003 and provided to NIST by the fiber manufacturer for this study in May 2004. This material will be referred to as virgin yam. 

The primary negative peaks in the difference spectra of the vest yams have low absorbance values and are seen at 931 cm 1072 cm 1422 cm 1440 cm 1506 cm 1560 cm , 1588 cm" 1657 cm" and 3400 cm". The officer s vest yam contains negative peaks with the highest intensity (absorbance), followed by the archive vest and the new vest, in decreasing order of intensity. This rank order in peak absorbance tracks the same rank order of tensile strength loss reported earlier. 

Figure 10.1. Difference spectra of the officer Sy new and archive vest yams, referenced to spectrum of virgin yarn.

In the first phase of this research, a comparative analysis study was carried out on yams from the back panel of the vest that had failed in the field (manufactured in November 2002, hereinafter referred to as the officer s vest), a new, non-deployed vest of the same model and constmction as the officer s vest (manufactured in September 2003, hereinafter referred to as the new vest), and a vest from the National Law Enforcement and Corrections Technology Center (NLECTC) Compliance Test Program Archive, of the same model and constmction as the officer s vest (manufactured in March 2001 and submitted for compliance testing in May 2001, hereinafter referred to as the archive vest). 

Tensile properties of yams extracted from the back panel of the officer s vest, a new vest, an archive vest, and virgin yam are tabulated in Table I. The yams from the officer s vest are clearly lower in all tensile properties relative to yams from the new and archive vests, as well as the virgin yam. The tensile properties of the yams from the archive vest are also lower than that of the new vest and virgin yams. 

Table II shows tensile strengths of yams extracted from new vests subjected to environmental chamber aging, as a function of exposure time. Average yam tensile strength dropped from 4.82 GPa to 3.08 GPa during the 157 d exposure period. Average strain to failure during the exposure period dropped from 3.31 % to 2.17 % while the tensile modulus remained steady in the range between 141 GPa and 149 GPa.

Figure 10.3. Difference spectra for PBO yarns extractedfrom aged vests, referenced to spectrum of yam taken at beginning of exposure.

Research and development in fluid jet technology led to its widespread use in film and web processing, mixers, reactors, and fiber processing. Applications to fibers alone includes Taslan bulked yams, jet piddlers, draw-jets, interlaced yams, bulk-crimped carpet fibers (BCF), and spunbonded products such as Reemay polyester, Typar polypropylene (PP), and Tyvek olefins. New fibers also were introduced Nomex aramid, especially suited for high-temperature applications Lycra spandex, an elastic textile yam Qiana nylon, with a silklike appearance and Kevlar aramid, used in products ranging from tires to bullet-resistant vests. 

Applications fibers, papers, yams some examples body armor, protection vests, military helmets, heat resistant gloves, vehicle armor, automitive components, fiber optics, adhesives, sealatn, composites, oil, gas, and many more ... 

---