Accelerated Weathering of Firefighter Protective Clothing Containing Melamine Fiber Blends

Abstract

In this study, the mechanical properties critical to the protective performance of firefighter turnout gear were evaluated in environmentally stressed outer shell (OS) fabrics containing melamine fiber blends. Environmental stress factors that affect the durability of turnout gear include temperature, ultraviolet (UV) radiation, moisture, abrasion, and laundering. The effect of fiber blend, fabric construction, and finishing processes including water repellent coatings and pigmented melamine-containing OS fabrics were also studied. Melamine-containing OS fabrics show comparable thermal protective performance and have superior tear resistance when compared to the traditionally used polyaramid blends.This study reveals that the thermal protective protection (TPP) rating of fabric assemblies incorporating environmentally stressed OS fabrics containing melamine fiber blends is well above the NFPA minimum TPP requirement of 35 Cal/cm 2 . However, the tear strength (measured using ASTM D 5587 standard test method ) of all melamine-containing OS fabrics exposed to environmental stresses was observed to have significantly deteriorated, and most OS fabrics, depending on fiber blend and fabric structure, would fail to meet requirements of NFPA 1971 standard. The study thus suggests that environmental stressing has a more detrimental impact on the tear strength than the thermal protective performance of OS fabrics. Deterioration in tear strength of all UV exposed OS fabrics is largely due to photodegradation of constituent fibers. Changes in tear strength of OS fabrics subjected to thermal exposures and laundering is cumulative effect of loss in tensile strength of single yarns and dimensional stability of the fabric itself. Furthermore, finishing treatments affect performance properties of fabric by increasing fiber packing factor in yarn, changing yarn crimp and yarn spacing thereby making dimensional changes to the fabric. Surface coatings alter tear resistance of fabric by influencing yarn slippage and fabric rigidity. Fabrics dyed with black and dark blue dyes cause less UV degradation of fibers than bright yellow and brown dyes.

Quantitatively evaluating the effects of flash fire exposure on the mechanical performance of thermal protective clothing

“…The elevated tear strength was merely seen in previous study based on fabric level tests. As presented in the study of Nazaré et al (2012), no statistical change was found in the tear strength of the fabrics after 56 days exposure at 50 o C, 50 percent RH with no UV irradiation. However, the tests with UV irradiation resulted in a similar deterioration profile as previously reported, which indicated the significant effects of test condition on results.…”

White Light-Photolysis for the Removal of Polycyclic Aromatic Hydrocarbons from Proximity Firefighting Protective Clothing

“…The fabric contained a mixture of Nomex ® (meta-aramid) and Kevlar ® (para-aramid) fibers, which can undergo oxidation forming acids, alcohols, and/or amides [ 33 , 34 , 35 ]. In the case of fiber degradation, it was possible to observe a reduction in the intensity of the amide bands and an increase in the intensity of the bands in the O-H and N-H regions.…”

“…As described in the NIST report 1751 [ 34 ], a way to assess changes in fabric constitution and possible wear from the decontamination process is by performing a tearing strength test. The NFPA 1971 [ 37 ] standard, which determines the necessary conditions for firefighting protective clothing, indicates that the fabrics of the outer layer of combat suits must present tear resistance higher than 100 N.…”