Phenolic foam is a type of plastic foam based thermal insulation that is produced by foaming a phenolic formaldehyde resin in the presence of a blowing agent, surfactant, and a suitable acid catalyst. It offers several benefits as a building thermal insulation:
Because of the above benefits and installed cost similar to other thermal insulations, the phenolic foam became a major commercial roofing insulation in the U.S. in 1980s. However, the chemistry of phenolic foam produced in 1980s involved the use of highly acidic sulphonic acid catalysts that would lead to formation of highly acidic leachate with pH in the range of 1.5-2.8 as the foam came in contact with water. This low pH level of leachate caused corrosion of metal elements in close proximity and led to a series of metal roof failures in the 1980s. By late 1990s, the phenolic foam was completely withdrawn from the U.S. building insulation market.
In 2014, Fraunhofer CSE was selected by the U.S. Department of Energy (DOE) Building Technology Office (BTO) to work with Atlas Roofing and the University of Tennessee, Knoxville, to develop a new type of non-corrosive, non-flammable, and inexpensive phenolic foam (DOE BENEFIT project award No. DE-EE0006715). During 2014‒16, Fraunhofer CSE led the research team to successfully develop phenolic foams with significantly reduced acidity. The pH level of the resulting phenolic foam leachate was over 4.5, even exceeding the project target. The corrosion potential of the novel formulations was found to be substantially reduced in comparison to the traditional phenolic foams.
As part of this DOE-sponsored work, we also developed novel biobased phenolic foam formulations that were derived from lignocellulose and bio-oil: