Preparation Of Thermal Insulation Materials Based On Silica Aerogels And Glass Fiber

As the aggravation of the energy crisis, energy conservation and emissions reduction becomes an important strategy in our country. Due to the building and industrial energy consumption occupies a large proportion in the total energy consumption, large numbers of thermal insulation materials are used to reduce energy consumption in the building industry and industrial manufacturing. The inorganic thermal insulation materials are not widely used due to its disadvantages, such as high thermal conductivity, high density and poor hydrophobicity. While the organic thermaol insulation materials are widely used, as it has excellent thermal insulation performance. However, the drawbacks of the organic insulation materials gradually arouse people’s attention, especially the fire risk will threaten the security of life.Silica aerogels are fascinating amorphous solid with the advantages of extremely low density, low thermal conductivity and high specific surface area. However, the actual industrial applications have been restricted seriously due to the inherent fragility, low strength and high cost. The main research content in this paper include:TEOS is selected as precursor and glass fibers play the role of reinforcements. Through sol-gel method, glass fibers strengthened silica aerogel composites are synthesized via ambient pressure drying. The influence of different precursor density on aerogel’ pore structure was studied. Under the conditions of optimal ratio, the density of the composite is 0.142g/cm3, water contact angle is 168°, and the thermal conductivity reaches 0.0228W/(m·K). The compressive strength of composites is 0.112 Mpa (under 35% of the deformation).Water glass is selected as precursor and glass fiber mat plays the role of reinforcements. Using two synthesis methods respectively, the thermal insulation composites based on glass fibers mat and silica aerogel are synthesized via ambient pressure drying. Influence of different precursor density on material properties was also studied. By comparing the composites produced by two methods. Two-step gel method has better performance on density. However, one-step gel method also has its merits: such as simple preparation process and lower cost. In addition, the composite produced by one-step gel method has better compression performance. While the composites produced by two-step gel method has good flexibility, it can be bent at any angle which is suited for piping insulation.Cone calorimeter test was also carried out to test the the combustion performance of composites. The value of HRR and THR has little difference under 35kW/m2, but it varied greatly as the heat flux increasing to 60kW/m2. Considering the fire safety of materials, the composites produced by water glass is more better. The lowest HRR is 49.60 kW/m2, and THR is 4.48MJ/kg under the heat flux of 60kW/m2. The composites was tested by building materials combustion heat value experiment device under the condition of pure oxygen. The sample prepared by TEOS as silicon source has the same the glass fiber content, so the combustion heat are between 9.2 to 10.0 MJ/kg. While the composite produced by sodium silicate as silicon source has different glass fiber content between 40% and 60%, so the combustion heat of materials will change between 3.8 to 6.3 MJ/kg.