Research On The Thermal Protection Performance And Heat And Moisture Comfort Performance Of Fire-fighting Fabrics

This paper studied the heat and moisture transfer properties of fabrics used for firefighters' protective clothing from two aspects of the thermal protection performance under low intensity radiation heat and the thermal and moisture comfort performance.First,the existing thermal protection performance(TPP)tester was modified.Two approaches(radiant protection performance approach and thermal stroed energy approach)were applied to explore the thermal protection performance on monolayer,double and multi-layer fabrics respectively'.It was found that the basic physical properties(thickness,weight),air gap,reflective trim as well as moisture barrier integrity has great influence on thermal protection performance.Based on the improved TPP test apparatus and air layer simulator,the influence of the air layer position,the thickness of the air layer and the water content on the second-degree burn time of the three-layer fabric system were discussed.The results demonstrated that these three factors were critical on the second-degree burn time prediction.Thus.it should be considered when evaluating protective clothing.In order to explore the thermal degradation under low level of radiant heat exposure,the single layer,the double layer and the multi-layer fabric were exposured with different time using the TPP tester.The appearance,color difference,water repellent properties,physical and mechanical properties,thermal protection performance of the fabric samples after exposure were investigated.It was found that a significant negative correlation between the breaking strength retention rate of warp and weft,the tear strength retention rate of warp and weft and the color difference of the single layer fabric,which can be expressed by a cubic curve regression model.The thickness,weight and permeability of the single layer fabric after exposure to radiant heat were increased and the crystallinity decreased,but the basic chemical structure did not change.After thermal exposure,the thermal protection performance of the single layer fabric did not change significantly,and the thermal protection performance of the double and multi-layer fabric system was improved.The thermal insulation performance of the fabrics used in firefighters' protective clothing was evaluated by the flat fabric insulation tester.The relationship between the thermal comfort and the influencing factors were analyzed.In order to evaluate the moisture comfort of the fabrics,the water-vapor transmition cup method was used to test the water-vapor transmition rate of both the single and multi-layer fabric systems,and the water-vapor resistance was calculated.The results showed that the thermal resistance of the multi-layer fabric combination can be predicted by the sum of the thermal resistance of each fabric.When the thickness of the air layer was gradually increased from 0 mm to 8 mm,the thermal resistance of the multi-layer fabric combined was increasing gradually,which indicated that the air layer played a positive role in improving the thermal insulation performance of the fabric.The water-vapor transmition rate of the multi-layer fabric combination gradually decreased with the increase of the thickness of the air layer.The relationship between the water-vapor transmition rate and the thickness of the air layer can be expressed by a quadratic polynomial.The relationship among the physical parameters of the fabric,the thickness of the air gap,the change of the environment and the moisture comfort were analyzed.