SYNTHESIS AND CHARACTERIZATION OF SILICA AEROGELS AS NOVEL THERMAL INSULATION MATERIALS – EXPERIMENTAL AND COMPUTATIONAL DETERMINATION OF THERMAL CONDUCTIVITY
Project no. 1320 · Status: Kapanmış · 2016
Summary
This thesis project aims to produce silica aerogels as a potential thermal insulation material in a lightweight, durable, monolithic, and hydrophobic structure. For this purpose, three different approaches for the synthesis of silica aerogels by the sol-gel method under ambient conditions were investigated. These approaches are; the incorporation of drying controlling agent, hydrophobization of the silica surface by silylation, and synthesis of in-situ hydrophobized aerogels by the co-gelation method. Among these approaches, the aerogels produced by the co-gelation method exhibited light and monolithic structure, high thermal resistance, and hydrophobic properties. The thermal insulation performances of the produced aerogels were revealed by experimental measurements and it was seen that the obtained results could compete with their counterparts in the literature. The heat transfer mechanisms in aerogels were investigated with theoretical models. It was concluded that the dominant transfer mechanism was related to the material density and microstructure. It was determined that the dominant transfer mechanism is the gaseous heat conduction in low-density aerogels and solid conduction in high-density aerogels. It was also concluded that the coupling mode has a direct effect on the prediction accuracy in thermal conductivity calculations.