Preparation Of Insulation Materials Of Silica Aerogels And Research Of Thermal Insulation Properties

Firefighters’ protective clothing are individual protective equipment for prevention of firefighters from flames and radiant heat hurts. To meet the thermal insulation performance, the current clothing merely increased the weight and thickness, which restricted the efficiency of firefighters. Apart from possessing the properties of traditional clothing, such as flame retardant and waterproof, the new clothing need excellent insulation materials which could reduce the thickness of insulating layer and finally brings convenience and efficiency while meeting the requirements of utilization. Aerogels, with the lowest density among the solid material in the world, possess super-high porosity. The thermal conductivity of the gas is much smaller than the solid, which make aerogels become the solid material with lowest thermal conductivity. Aerogels with modifications could bear high pressure and high temperature. Due to these unique properties, it could be used as super insulation materials for the application of clothing field. Firefighters’protective clothing are always subjected to a series of test of thermal insulation and fire resistance performance before putting into use. The improved aerogels could meet these demands of thermal insulation, high strength, high toughness and fire resistance. This paper synthesized aerogels of porous insulating material. Aerogels with more excellent performance are obtained by changing the modifiers. The prepared aerogels, integrated with reinforced fiber, would be the raw materials for the preparation of insulation materials of aerogel blankets.Ambient pressure dried hydrophobic silica aerogels were fabricated by the two-step sol-gel method where tetraethylorthosilicate(TEOS) acted as precursor. Modification study was conducted to get aerogel materials with better features. Microstructure of as-prepared silica aerogels was analysed by Scanning electron microscope (SEM); the chemical components and the degree of hydrophobicity were identified by Fourier transform infrared spectra (FT-IR); the thermal evolution was studied by Thermogravimetric and Differential scanning calorimeter (TG-DSC). Density, porosity, BET surface area, pore size and contact angle of samples were also tested. Results show that the silica aerogels modified with trimethylchlorosilane(TMCS) have relatively better characteristics, possessing density of0.115g/cm3, contact angle of158°and BET surface area of1067m2/g. The average pore diameter of the modified aerogels, which have large amount of mesopores and only a small quantity of micropores and large pores, is13.40nm. Therefore, the modified aerogels are typical of mesoporous materials.The prepared aerogels beforehand were modified in strength and brittleness under the action of white emulsion and surfactant of KH-550, and after this the modified aerogels were integrated with fibers which were reinforced by thermal treatment and this finally synthesized the SiO2aerogel blankets we needed. We optimized the formula by studying the alteration of thermal conductivity with the different heat treatment temperatures of fibers and the variable volume content of white emulation and aerogels in the mixed solution. The results indicate that after the complete volatilization of softening agent on the fiber surface, the higher the heat treatment temperature, the lower the thermal conductivity. Besides, the thermal conductivity decreases along with reduce of the amount of white emulation. To some extent, we can gain even lower thermal conductivity when the aerogels sufficiently dissolved in the solutions, which plays a role in decreasing the thermal conductivity. In conclusions, the specimen with thermal conductivity of0.048W/m·K can be synthesized with white latex content of3ml and aerogel content of10g under the heat treatment temperature of500℃The samples will be tested under low radiation surroundings to further verify their heat-insulating performance. The test results showed that the temperature rising was moderate under the radiation intensity of10kW and15kW. Because it was within the limits of heat absorption, the temperature of the lower surface will continue to be gently raised. The temperature rising rate was drastic on both upper and lower surfaces in the case of radiation intensity of20kW. The temperatures of the upper surface tended to be consistent almost at the beginning and the temperatures of lower surfaces change smooth and finally stabilized at a certain moment for reaching the limitations of insulation. Combined with insulating performance of different samples in the same radiation intensity, the aerogels blankets prepared at the optimized conditions have the desirable quality in heat insulation.