The Performance Study Of Thermal Portective Fabric Systems Under Thermal Radiation And Friction Hazard

Protective clothing and textile-based equipment are critical for firefighter to ensure their safetyand health. Ineffective protection at a fire scenario with multiple hazards can cause injury andfatality among victims and firefighting personnel. Firefighters are facing quite complexenvironments and conditions in which firefighters must operate, a wide range of hazards are possible.This includes thermal, chemical, biological, radiation and physical hazards. The thermal exposure isthe major one which ranges from conduction, convection, hot liquid, steam and hot solids. All thesehazards present the specific characteristics in term of protection and injury. After the exposure ofthese hazards, the performance of thermal protective clothing will change. However the changes inprotective performance were not fully investigated. The aim of this study is to investigate theperformance changes of thermal protective fabric systems after thermal radiation hazard. Themodified TPP tester was applied and the thermal protective fabric friction simulate tester weredeveloped to simulate the actual wearing abrasion. In order to further study the relationship of thethermal protective performance provided by these fabric systems and their fine structure change,Some examination approaches were applied to investigate its change, such as SEM, FIR and XRD.The results obtained from this paper can provide theoretical guidance for fire protective clothingperformance evaluation and practical application of thermal protective clothing.Four high performance fabrics (aramid IIIA, aramid982, aramid-FR viscose and Kevlar-PBI)were selected for the outer shell with moisture barrier and thermal liner each as an ensemble in thestudy. The modified TPP tester was used to generate20kw/m2of laboratory simulated thermalradiation hazard with30s and90s’ radiation time. The heat flux measured from the sensor wasobtained and used to predict2nddegree skin burn injury. The thermal protective fabric frictionsimulate tester was used to simulate actual wearing abrasion. The performance in terms of seconddegree burn time provided by these fabrics before and after wearing simulation was predicted andcompaired.The experiment results showed that the thermal protective performance of fabrics would beincreased after thermal radiation. Fabrics would shrink after thermal radiation, the fabric shrinkagewould cause the fabric thickness’s increasing, which would increase the thermal protectiveperformance of the fabrics, the actual fire protective clothing’s thermal protective performance changes did not necessarily comply with the law. After the fabrics were made as fire suits, the airlayer integrity between human body and protective clothing would reduce, its thermal protectiveperformance would be significantly lower.Fabrics might not be immediately apparent performance change, once after the process ofwearing, the thermal protective performance appeared to be markedly reduced. Friction woulddestroy the fibers of the fabrics and made the fibers thinner, which would reduce the heat insulationperformance of the fabrics. Thermal protective fabrics would shrink after radiation, greater changeswould increase with the increasing of irradiation time. The thickness of the fabrics increased with theincreasing of the radiation time. The weight of the fabrics changed because of the fabrics’ shrinkageand decomposition. Under the condition of low intensity of thermal radiation, fabric fibers’permeability were mainly influenced by the fibers surface coating’ s melt, the moisture permeabilityof the fabrics changed just a little. The weight and thickness of the fabrics would decrease and thepermeability and moisture permeability would increase after the friction damage. The damage offriction was more obvious after the fabrics were damaged by thermal radiation.Under the condition of thermal radiation intensity of20kw/m2, in90s, the tear strength andtensile strength of the fabric would decrease with the increasing of the radiation time. After thefabrics were damaged by friction, the tensile strength and tear strength of the fabrics decreased, andthe influence of friction was more apparent after the fabrics were damaged by thermal radiation. Thecrystallinity of Kevlar-PBI fiber and aramid982fibers were influenced just a little. The crystallinityof aramid IIIA fiber and aramid-FR viscose fiber would decrease with the increasing of the radiationtime, which would decrease their strength. After thermal radiation, the thermal degradation of thepolymers would start after radiation. After the thermal degradation of the polymers, the mechanicalproperties of the fabrics would change. The crystallinity of fabrics didn’t change after the frictiondamage and the degradation of polymers would not occur after friction.