Vacuum Insulation Panels

        Vacuum Insulation Panels or VIPs consist of a rigid core encapsulated in a gas-tight envelope from which air is evacuated. The envelope prevents air from reentering and the core keeps the walls from collapsing. The encapsulated vacuum greatly reduces heat conduction and convection; therefore, it is desirable for the core to be highly micro(nano)porous while maintaining exceptional structural integrity. 
        
During Phase I work funded by the U.S. Dept of Agriculture, Mayaterials produced robust cores and complete VIPs, as shown in the photos below, with a high thermal resistance of R-20/in. Current home insulation materials, such as polystyrene and polyurethane, have R-values of 3-7/in.
        
The novel core materials for our VIPs have a very low-density, 0.35 - 0.55 g/cm3, and are derived from the agricultural byproduct rice hull ash (RHA). RHA is an abundant, 100 M ton/yr worldwide, agricultural waste material produced from burning rice hulls often with co-generation of electricity, which is also a byproduct of rice production.
        
These successes have led to a Phase II award from the USDA starting September 30th, 2010 to scale the facile processing techniques to produce large cores and optimize envelope technology. The ease of manufacture and low-cost starting materials combined with the potential energy savings make these VIPs an economically competitive green technology. We have already lowered our densities to ≤ 0.30 g/cm3 which should equate to R values of 25-35.
 


        These core materials are made from high surface area silica that is extracted from RHA through low temperature and facile chemical syntheses. The resulting
silicas can have surface areas up to 700 - 800 m2/g. Below is a SEM image of our high surface area silica.
 

        We have learned to make these
silicas superhydrophobic as well. Instead of vacuum sealing the cores, they can be dip-coated in our silsesquioxane based coating systems to form a very hydrophobic surface. This waterproof surface makes these agricultural waste product based materials ideal for building façade insulation. The water contact angles of these “weather-proof” materials are 140° - 150°, see below. Water droplets actually “bounce” off these surfaces!