Studies On Synthesis And Thermal Insulation Property Of Silica Aerogel/Polystyrene Composite Materials

With the continuous development of modern society, energy consumption is getting higher and higher. How to make better use of energy is one of the focuses of public attention. And thermal insulation material which is a kind of effective method to improve the energy efficiency is getting more and more attention.Silica aerogel due to its e xcellent heat preservation properties has been wide ly used as thermal insulation material. But silica aerogel also gets some congenital deficiencies, such as its fragility and the difficulty of being processed. This limits its application. With the development of science and technology, researchers are working hard to find better thermal insulation materials.In this experiment, the silica aerogels were prepared and composited with polystyrene(PS) to get a kind of new thermal insulation material. The silica aerogel was prepared with tetraethylorthosilicate(TEOS) as the precursor and ethanol as the solvent through a gel-sol method. Then aerogels was modified with KH-570 before compositing with polystyrene. The properties of silica aerogel/PS were investigated in detail.In this thesis, experimental conditions of aerogels were investigated and the optimum reaction conditions were obtained. Results showed that the best molar ratio of TEOS: ethanol: water is 1:6:6, the optimum reaction temperature is 40 ℃. The formamide is used as a kind of dry control chemical additive(DCCA), and its molar ratio to TEOS is 0.2 to 1. At the optimum conditions, silica aerogel with the density of 0.2004 g/cm3 was obtained.Silica aerogel is a kind of material with amorphous structure. The unmodified silica is hydrophilic, which makes it is easy to fracture in the process of preparation. In this paper, silica aerogel obtains good integrity through the modification with KH-570. Modification also improves the porous structure of aerogels at the same time. The specific surface area of aerogel increases from 333.12m2/g to 530.11m2/g, and the aperture size increases from 3.107 nm to 4.251 nm with modification of KH-570. The composite conditions of the modified silica aerogel and polystyrene were investigated, and the optimum condition is 80 ℃, n(SiO2) : n(St) = 1 : 6, the dosage of initiator KPS is 0.2 g. The thermal conductivity of composite materials is lower compared to the pure polystyrene and it confirms that the composite technique can improve the thermal insulation property of polystyrene. However, the monolithicity of the composite materials of silica aerogel/PS still needs further improvement.