Polyurethane-Based Aerogels for Use as Environmentally Acceptable Super Insulants

The introduction of VACPAC panels (polyurethane-based vacuum insulation panels) into the appliance market have been discussed extensively. 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 next generation super-insulation materials called aerogels. Aerogels are light weight, 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. Laboratory development work of polyurethane- and polyisocyanurate-based organic aerogels has now been completed. 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 optimised 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. Following on from the initial laboratory development, ICI Polyurethanes is investigating the potential routes to market for such a product whilst simultaneously working on methods for scaling up its technology. Initial tests are in progress and further process and product optimisation is being achieved.