Silika aerojel polimer kompozitlerinin hazırlanması ve karakterize edilmesi

In this study, new nanotechnology-based high performance insulation systems for energy efficiency, nanostructured composites of silica aerogels with polymers are being developed as core materials for vacuum insulation panels in buildings. Monolithic composites of a wide variety of polymers with silica aerogels were synthesized by modification of the conventional sol-gel method to produce silica aerogels. The polymers used in the study are poly(ethylene block poly ethylene glycol) (PEPEG), poly(vinyl pyrrolidone) (PVP), poly(vinyl acetate) (PVAc) and poly(methyl vinyl ether) (PMVE). Characterization of the composite materials was performed by Fourier Transform Infrared - Attenuated Total Reflectance (FTIR-ATR) spectroscopy, Thermal Gravimetric Analysis (TGA) and by Nitrogen Physisorption using BET. Both transparent and opaque crack-free monolithic composites suitable for testing and use in VIPs were obtained. The presence of polymer in the composites was confirmed by IR spectroscopy and TGA. The composites were mesoporous materials with high surface areas around 800 m2/g and average pore sizes around 5 nm. Incorporation of polymers did not significantly change the pore size distribution and the specific surface area of the pure silica aerogels. The effects of the time of polymer addition at various stages of the conventional sol-gel process such as before/after the hydrolysis step and during the aging step, on the properties of the composites were investigated. Opacity was found to be correlated to the phase separation of the polymer from the reaction mixture. The effect of polymer content on the resulting properties was also investigated along with density, porosity and shrinkage calculations.