Preparation And Properties Of Wearable Heat-induced Fire Warning Aerogel Electronic Textile

Fire is one of the most threatening natural disasters to public safety and social development.In the process of fire rescue,firefighting protective clothing is necessary to protect firefighters from burning.When firefighters are exposed to excessively high fire temperature(600-800?),due to the existence of the heat insulation layer of the fire clothing,firefighters cannot know the outer temperature of the protective clothing in real time and accurately.The outermost layer of the fire protective clothing is vulnerable to high temperature and burns,threatening the safety of firefighters.Based on the change characteristics of temperature response resistance of semiconductor nanomaterials,an electronic textile with both ultra-sensitive temperature response and self-power capability was prepared,and it was integrated into firefighting clothing.When the surface temperature of the clothing reaches over 350?,the warning electronic fabric triggers the fire warning system within 2?3 s,which can send out warning signals to remind firefighters to stay away from the high temperature fire source in time.Taking calcium alginate(CA),nano-ferric oxide(Fe₃O₄NPs)and silver nanowires(Ag NWs)as raw materials,the heat-induced conductive aerogel fiber(TIC-AF)was prepared by wet spinning,sol/gel conversion,solvent exchange of water/alcohol,freeze drying and spraying.By controlling the concentration of alcohol in the water/alcohol solvent exchange system,the internal pore morphology of TIC-AF is regulated.The experimental results show that when the water/alcohol mixture concentration is 30 wt%,TIC-AF exhibits the microstructure of"porous core and dense sheath",the pore diameter is distributed between 4-14 nm,the tensile fracture strength is 13.5 MPa,the fiber density is 0.033 g/cm~3,and the specific surface area is 38 m~2/g.Based on the temperature response resistance variation characteristic of Fe₃O₄NPs,when TIC-AF woven self-powered fire warning(SFA)electronic textile encounters high temperature(>350?),its resistance drops rapidly from 10~4?to 10~2?within 2.6 s,thus triggering the fire warning system.When the electronic fabric encounters high temperature again,it can still send out early warning signal within 3 s,and can realize the repeated high temperature warning ability within the temperature range of 100-400?.The early-warning electronic textile has good flexibility.After 200 bending cycles(180°),it can still trigger the fire early-warning system within 2?3 seconds when exposed to high temperature.In addition,based on the synergistic flame retardant effect of calcium alginate and ammonium polyphosphate,electronic fabrics exhibit excellent flame retardant properties,with a peak heat release rate of 3.819W/g and a total heat release rate of 0.1 KJ/g.SFA electronic textile as positive friction material and PTFE cotton fabric as negative friction material,the fabric-based friction nanogenerator(TENG)was constructed to realize the energy harvesting and self-power sensing capability of electronic textile to human mechanical energy.The effects of aerogel fiber diameter,spraying times of silver nanowires,PTFE concentration finishing cotton fabric and temperature on the electrical output performance of TENG were studied.The experimental results show that when the concentration of PTFE is 10 wt%,the spraying times of Ag NWs is 20 times,and the fiber diameter is 1.0 mm,TENG has the best electrical output capacity(3.8 V).When subjected to250?,the TENG output voltage still retains 47.7%of the open circuit voltage at room temperature.Therefore,the SFA electronic textile base TENG can be integrated into the fire protective clothing to provide electricity for the fire warning system,so as to overcome the weakness of the existing power supply flexibility is difficult to integrate into the clothing.In this work,a fire warning aerogel electronic textile with functions of temperature monitoring and self-electricity is prepared,which can be used as a fire warning sensor in fire clothing.The high temperature warning function and self-power ability of fire protective clothing are endowed,which ensures the safety of firefighters.