Study On Synthesis Technology Of Silica Aerogels/Polystyrene Core-shell Composite Materials

It is very significant to develope energy-saving technique such as a new type of energy-saving material due to energy shortage and inefficent consumption at present. Nanoporous silica aerogels is a new type of energy-saving material characterized by ligh, nano hole and non-crystalline which has many excellent properties such as superior heat insulation, lower coefficient of heat conductivity and easier adsorption. However, its defect hampered the practical application which include low strength of structure and hydrophile. Polystyrene board possessing high strength, low hydrophile and easy manipulation has become the mainstream energy-saving material of external wall insulation system, but its field of application was limited by its high coefficient of heat conductivity. This paper apply combination of organic and in-organic to prepare a new type of efficient composite energy-saving material.The composite micro-sphere material possessing the structure whose core consisted of the SiO2 aerogel particle, and its shell consisted of organic polystyrene. The addition of KH570 in the processing of surface modification of aerogel was analyzed. The effect of modification was characterized by infrared spectrum and the test of distribution. The appropriate proportion of polymerization was decided by the orthogonal test. The influence factors such as ultrasonic dispersion, pH, temperature and time were analyzed by conversion percent of polystyrene and microscopic morphology, and the relation of density and coefficient of heat conductivity was measured. Finally, the formation mechanism of composite microsphere was investigated, and the component of composite microsphere was defined through the microscopic investigation.The results showed that:when the mass ratio of KH570 and aerogel was 45%, the modified effect is best. The infrared spectrum analysis demonstrated that KH570 have already been successfully grafted to the surface of the aerogel particles. Orthogonal experiment selected the best ratio of the polymerization:the SiO2 aerogel of modification was for 1.0g, styrene for 10ml, SDBS for 0.025g and KPS for 0.1g. At the same time, the effects of pH value to styrene conversion and core-shell structure morphology were got, and the optimal pH value is 7. When ultrasonic power for 500W and dispersing time for 20 min, the core-shell nanocomposite morphology was best. As temperatures rose, the conversion of styrene became bigger, and the maximum is 68.01% at 85℃. TEM observation showed that:the optimum temperature was 75℃when its core-shell structure morphology was best. Through viscosity test of the emulsion the best polyreaction time was 10h. Study found that thermal conductivity of core-shell composite particles decreased compared with pure polystyrene. Through microscopic analysis of the core-shell nanocomposite sample, the result showed that:the ingredients of the "core" were SiO2 and the "shell" were the polystyrene.