Polyurethane-Based Aerogels for Use as Environmentally Acceptable Super Insulants in the Future Appliance Market

ICI Polyurethanes has talked extensively about the introduction of VACPAC * panels (polyurethane-based vacuum insulation panels) into the appliance market. Details have been presented at previous SPI and Utech meetings. In the meantime, extensive field tests have been carried out and, recently, several commercial models have been launched based on "VACPAC" panel technology. Researchers all over the world are now working on a next generation super-insulation material called aerogels. Aerogels are lightweight, air-filled materials with a low thermal conductivity. The microporosity of these materials greatly reduces the air conductivity. Most of these materials are silica based and rather brittle in nature. Some work has been reported on organic polymeric aerogels. We have now completed the laboratory development work of polyurethane- and polyisocyanurate-based organic aerogels. These materials offer a thermal conductivity of 7 mW/mK at a modest vacuum of 10 mbar. When no vacuum is applied, and the aerogel is completely filled with air, the thermal conductivity is 22 mW/Mk. This paper describes the factors that have been optimized to develop an aerogel material which, in the long term, it is believed, will be a viable filler material in moderate vacuum technology. The project has been focused towards the appliance industry where energy requirements are becoming more and more stringent.