Structural Design And Performance Study Of Basalt/Polyimide Three-Dimensional Spacer Fabric For Thermal Protection

With the development of society and the expansion of the scale of industrial production,the frequency of fires is getting higher and higher,and the harm to human beings is becoming more and more serious.Whenever a fire occurs,firefighters are those who rush to the front line for firefighting,rescue and disaster relief.They need to run and put out fires in complex and high-temperature fire environments,and their own safety is greatly threatened.Fire suits for thermal protection is an important barrier to protect the lives of firefighters.It needs to have good high temperature and heat protection performance.At the same time,in order to facilitate firefighters to work in the fire scene,fire-fighting clothing should also have good wearing comfort.In this paper,a three-dimensional spacer woven fabric is designed for fire-fighting clothing fabrics for thermal protection.The outer layer and spacer yarn of the fabric are made of high temperature resistant and environmentally friendly inorganic fiber basalt filament,the inner layer is made of soft,comfortable and high temperature resistant polyimide fiber,and a certain air layer is reserved in the middle to improve the thermal insulation performance of the fabric.This paper mainly studies the effects of warp spacer yarn span and spacer height on the mechanical and thermal properties of fabrics.First,we design and weave basalt/polyimide three-dimensional spacers with warp spacer yarn spans of 5,11,17,and 23 wefts.fabrics,and their mechanical and related thermal properties were tested to study the effect of spacer yarn warp span on fabric properties.After obtaining the optimal spacer yarn span,basalt/polyimide three-dimensional spacer fabrics with different spacer heights were prepared,and the spacer heights were 0,4mm,8mm,and 12mm,respectively.The effects of different spacer heights on spacer fabrics were tested and studied.The results show that the fabrics with the warp spacer yarn spans of 5,11,17,and 23 weft yarns are well formed,and the spacer effect is obvious.After testing,all fabrics have good tensile rupture,burst and compression resistance,which can meet the Mechanical requirements of fabrics.In terms of flame retardant performance,the flame retardant performance of the fabric mainly comes from the material itself,so it is not greatly affected by the fabric structure.The limiting oxygen index of the outer basalt fabric layer is greater than 69%,and the inner polyimide fabric layer All are greater than 35%,there is no melting,dripping phenomenon,no smoldering,afterburning in the vertical combustion process,the mechanical properties and flame retardant properties of the fabric,and the flame retardant properties of the fabric are excellent.In terms of thermal stability,after all fabrics are heat-treated at 260±5℃,the dimensions and quality of the fabrics in all directions have no change,no thermal shrinkage,curling and softening,and the thermal stability is excellent.In terms of thermal insulation performance and thermal protection performance,the thermal resistance value of the fabric with the spacer yarn span of 17 weft yarns is up to 0.203℃·m~2/W,and the maximum TPP value reaches 1136 k W·S/m~2,which is much higher than the GA10-2014 standard.value.Therefore,the fabric spacer yarn span is preferably 17 weft yarns.The fabrics with different spacer yarn heights have obvious spacing effects.The fabrics with a height of 0,4mm,and 8 mm have good surface morphology,and the fabric with a height of 12 mm has larger surface gaps.The test shows that the tensile fracture and burst properties of the fabrics at all spacing heights are very good and meet the standard requirements;the compression recovery rate of the fabrics with heights of 4mm,8mm,and 12 mm is about 97%,and the compression resistance is excellent.In terms of flame retardancy and thermal stability,it is similar to the test results of fabrics with different warp spacing yarns.After heat treatment,the size and quality of the fabric remain unchanged,the shape and quality of the sample are stable,and the thermal stability is excellent.In terms of thermal insulation performance and thermal protection performance,the thermal resistance value of the fabric with an interval height of 8mm is 0.241℃·m~2/W,and the TPP value is the largest,reaching 1247 k W·S/m~2,so the fabric interval height is preferably 8mm.In order to better study the heat transfer process of spacer fabrics,two equivalent models were established based on the actual structure of the spacer fabric with a height of 0 and 8mm,and the thermal resistance of the fabric equivalent model was calculated through steady-state simulation.Compared with the experimental results,it is found that the error of the two is within12%,indicating that the established equivalent model can accurately reflect the heat transfer performance of the fabric.After the validity of the models was verified,transient heat transfer simulations were carried out for the two models at a high temperature of 100°C,respectively.The results showed that the lower surface temperature of the fabric with a spacing height of 8mm was lower than that of the fabric with a spacing height of 0 at the same time.And the temperature difference between the upper and lower surfaces is also larger,indicating that the air layer in the spacer fabric can effectively slow down the heat transfer.