Study On The Influence Of Fabric Surface Properties On Thermal Protection Performance Of Outer Layer Materials Of Fire-fighting Suits

Fire fighting protective clothing is an important protective equipment for firefighters to carry out rescue work in the fire scene.The fire scene is complex and harsh,and the improvement of the performance of fire fighting protective clothing is crucial.The heat in the fire scene is mainly radiant heat.In order to avoid the absorption of heat rays by fabrics more effectively,the fiber types used for the outer layer materials of fire fighting protective clothing were investigated based on the energy band theory.Nine kinds of fabrics were woven with aramid fiber and polysulfonamide fiber with different yarn ratio and fabric weave,and the thermal properties,mechanical properties,air and moisture permeability and dimensional stability of each fabric were tested.Then,the optimum fabric was dyed,and the K/S value,reflectivity and thermal properties of the dyed fabric were tested,and compared with the undyed fabric.Compared with commercial fabrics,the aramid/polysulfonamide fabric developed in this paper has better thermal protection and lower cost than aramid,which provides a theoretical basis for optimizing the performance of the outer fabric of fire fighting protective clothing.The results are shown below:(1)The band gap(Eg)of inherent flame retardant meta aramid fiber was 3.044 eV and that of polysulfonamide fiber was 2.710 eV,and their band gap avoided the corresponding range of visible light with long wavelength and infrared light(Eg<0.5eV or Eg?2.5 eV?3 eV).(2)When the proportion of aramid and polysulfonamide yarn was 25%/75%and the fabric weave was twill 1/3,the breaking strength in warp and weft directions was1134 N and 824 N respectively,the TPP value was 359.43 kw·s/m~2,and the moisture permeability was 3457.64 g/(m~2·d),and the above properties were the best among the nine fabrics.The tearing strength,flame retardancy and dimensional stability of the optimum fabric were excellent and met the industry standard(GA10-2014),and the heat insulation performance was excellent,and the air permeability was 127.11 mm/s.(3)The second degree burn time of dyed fabric was longer than that of undyed fabric,and the molecular structure of the dye affected the reflectivity of the dyed fabric to the infrared ray.The anthraquinone structure is not conducive to reflecting infrared rays.The cyanine conjugated structure whose basic skeleton is connected by benzimidazole and benzothiazole heterocycles through methine,quinophthalone structure and bisazo structure are conducive to reflecting infrared rays.The thermal protection performance of dyed fabrics will be reduced by radiant heat,and the thermal protection performance of undyed fabrics is almost not affected by radiant heat.According to the test results,the thermal protection performance of the fabrics from high to low is:cationic bright yellow 7GL dyeing>palanil yellow 3G dyeing>disperse yellow E-RGFL dyeing>disperse red 3B dyeing>disperse blue 2BLN dyeing>unyed fabric.(4)The TPP value(463.6 kw·s/m~2)of the optimum fabric after dyeing is 21.2%higher than that of commercial aramid fabric and 16.4%higher than that of commercial polysulfonamide fabric.