Preparation And Characterization Of Fiber Reinforced Cross-linked Aerogels

Aerogel is a kind of nanoporous solid material with three-dimensional network, ultra-light, heat insulation, sound insulation, energy absorption and many other excellent properties, application prospects. SiO2 aerogels are the most widely used and the most studied aerogels materials. However, hydrophilicity, poor mechanical properties, Complicated production process and so hindered its application and promotion. Preparation of SiO2 aerogels composite by modified SiO2 aerogels is an important way to solve problemsSiO2 aerogels composite samples were prepared by sol- gel method and atmospheric evaporation. The modification effect of SiO2 aerogels hydrophobic treatment, polymer crosslinking and fiber-reinforced was studied by structural and performance analysis.Firstly, SiO2 aerogels make changes from hydrophilic to hydrophobic by replacing-CH3. SiO2 wet gel was prepared by sol- gel method, with trimethylchlorosilane(TMCS) as a hydrophobic agent and tetraethylorthosilicate(TEOS) as the silicon source, and then hydrophobic SiO2 aerogels are prepared by soaking SiO2 wet gel and atmospheric evaporation. The density, microscopic structure, hydrophobicity, functional group, phase and other performance of the sample ware characterized. The results show that SiO2 aerogels with nanoporous structure, hydrophobicity and low density was prepared by hydrophobic treatment and and atmospheric evaporation.Secondly, SiO2 aerogels ware modified by the crosslinking of isocyanate and-NH3. Silica source is prepared by mixing TEOS, and 3-aminopropyl triethoxysilane(APTES) and N3200 and N3390 as a crosslinker. Polymer crosslinked SiO2 aerogels ware prepared by soaking SiO2 wet gel in crosslinking agent solution and atmospheric evaporation. The density, microstructure, thermal stability, organic content, functional groups and compressive strength of the sample ware characterized. The results show that SiO2 aerogels still has a nanoporous structure and no cracking after polymer crosslinking. The sample density is reduced by 30% and compressive strength increased by 3 times. Polymer layer and SiO2 backbone are connected with chemical bond, the polymer content was approximately 55%.Finally, mechanical properties of SiO2 aerogels ware enhanced by doping the fiber. The mechanical properties of hydrophobic SiO2 aerogels and polymer crosslinked SiO2 aerogels ware enhanced by the addition of chopped glass fibers, chopped carbon fiber and glass fiber cloth. The density, flexural strength, microstructure and other properties of the samples were characterized. The results showed that the density of aerogels increases about 10%, but its flexural strength upgrade nearly doubled after fiber composite. Compared to the chopped glass fibers, chopped carbon fibers have better enhancement effect, the same amount of addition of glass fiber cloth reinforced better.