Previously we quantified the chemical and mechanical deterioration of polyaramid and polybenzimidazole-based protective clothing fabrics that resulted from concurrent thermal, moisture, and simulated sunlight exposure. This paper reports on individual effects of UV irradiation at ambient conditions and moisture effects at elevated temperature of 50 oC on performance properties of outer shell fabrics used in firefighters turnout gear. The mechanical properties which most often decide protective performance of firefighters turnout gear include unidirectional stretching, tear resistance and elastic properties have been tested before and after accelerated weathering process. To assess and compare the protective performance of outer shell fabric samples against UV radiation the ultra violet protection factor (UPF) has been calculated. ATR-FTIR analysis has been used to elucidate the chemical changes induced by weathering process. Results suggest that the deterioration in the physical properties of polyaramids and polybenzimidazole are mainly due to photo oxidative reactions, which change the chemical composition of the polymeric system. These chemical changes are known to be responsible for the loss of mechanical performance as well as the color change. The UV exposures however, has less detrimental effect on UPF of fabrics studied. Results suggest that it is important to well define the storage conditions for firefighters turnout gears so as to maintain their performance properties.
Citation: Technical Note (NIST TN) - 1746Report Number:
NIST Pub Series: Technical Note (NIST TN)
Pub Type: NIST Pubs
firefighter protective clothing