Development And Performance Study Of SiO₂ Aerogel Fire-fighting Clothing Insulation Lining

When a fire accident occurs,firefighters often need to get close to the open fire,which has a strong thermal impact.Fire-fighting and rescue clothing is the thermal protective clothing worn by firefighters in fire rescue activities,and it is also the last barrier to protect firefighters’life safety.Thermal insulation layer played a major role in the protection of thermal injury.Most of the existing heat insulation linings achieveed the heat insulation index by increasing the thickness,which makd the fire-fighting clothing bulky.And these insulation layers were difficult to take into account the mechanical properties of the fire clothing.When firefighters were working at the scene,they were easily hit by falling objects.Therefore,it was necessary to improve the mechanical properties as well as the thermal protection properties.Aerogel nanomaterials had excellent thermal insulation properties,but their mechanical properties were poor.The ball particles had incomparable advantages.Accordingly,the development and performance study of SiO₂aerogel fire rescue clothing insulation layer were carried out,and the following research results were obtained.（1）SiO₂ aerogel spherules were prepared from SiO₂aerogel powder,ammonia free latex and water as raw materials.The prepared spherules were characterized by scanning electron microscopy,specific surface area and pore structure,fourier transform infrared spectroscopy,shrinkage,density and porosity.The results showed that the microstructure of SiO₂ aerogel spherules was compact,the specific surface area was 567.6507m~2/g,the average pore diameter was 31.6822nm,and SiO₂ aerogel spherules were mesoporous materials.From the analysis of functional groups,it was known that the properties of the combination of aerogels and ammonia free latex were affected by changing the internal structure.There was no chemical reaction between the two.（2）On this basis,the mechanical properties experiments under different pressures were carried out.The compression capacity of single aerogel spherule and whole spherules was studied.The elastic modulus of spherule was calculated.The mechanism of force transmission between spherules was proposed and the force transmission capacity was analyzed.When a single SiO₂aerogel spherule was loaded and the pressure reached 2k N,the sample cracked locally and the transmission force decreased gradually in the 1-5 circles,but the transmitted force was significantly smaller by the fourth circle.When SiO₂ aerogel spherules were subjected to force,there was no cracking after 15k N pressure.（3）Macroscopically,the heat resistance of the spherules at 80-200℃was tested.The surface carbonization rate was used as the heat resistance index.At the same test temperature,the greater the degree of blackening of aerogel spherules,the longer the time required.When the average temperature was lower than 152.4℃,the maximum blackening degree on the surface of the pellets was less than 100%.The thermal stability of spherules was tested from microcosmic.The total weight loss rate of aerogel powder was 15.8%,and the total weight loss rate of SiO₂aerogel spherules was 53.7%.When the temperature was relatively low（less than 260 degrees）,the thermal stability of SiO₂ aerogel spherules was relatively better,and the temperature had reached the ambient flame temperature of firemen in the fire field.The heat insulation performance of single SiO₂ aerogel spherules and a number of SiO₂ aerogel spherules was studied.The formula of thermal resistance of a gap in fire rescue clothing was calculated to be 5411.28 K/W.（4）Finally,the mechanical and thermal properties of the spherules were studied.The filling mode of lining of fire rescue suit was determined.The plane filling mode was to fill the center spherules and 1-3 circle spherules with the hexagon as a unit.Through the comprehensive analysis of the total energy consumption and thermal performance,it is concluded that the fire rescue clothing should be filled with two layers in the space,and the filling should be closely arranged to each part of the lining.