Protective Performance of Environmentally Stressed Fabrics Containing Melamine Fiber Blends

In this study, the mechanical properties critical to the protective performance of firefighter turnout gear were evaluated for 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/cm². 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.