Fraunhofer CSE and Partners Develop New Bio-Based Phenolic Foam
Phenolic foams produced in the United States in the 1980s were highly acidic in nature (pH ~2.0‒3.0) because they used strong sulfonic acid catalyst in their chemistry. This led to a series of corrosion-related failures of metal roofs containing phenolic insulation when the insulation came in contact with the water, and ultimately phenolic foam was withdrawn from the U.S. building market by the early 1990s.
A project team comprising researchers from the University of Tennessee, Knoxville, Atlas Roofing Corporation, and Fraunhofer CSE has recently developed a non-corrosive, non-flammable, inexpensive phenolic foam derived from bio-based components to be used as a building insulation. The project is funded by the U.S. Department of Energy Building Technology Office.
The project team is targeting pH levels greater than 4.5 and a thermal conductivity of 0.018 W/m-K using novel foaming and foam-curing techniques: To reduce the foam acidity the researchers are substituting highly acidic sulfonic acid catalyst with less acidic, bio-based, and inexpensive organic compounds. Light-weight nanocellulose fibers are added to mechanically reinforce the foam matrix. In addition, the thermal performance has been improved by using inexpensive infrared opacifiers and reflective foil facing. If the full commercialization of recent developments is successful, a new bio-based foam with a higher pH value will provide the building industry with an innovative option for insulation applications. So far the results are promising: Recent samples boast a pH level of 4.5. Future work will include continued attempts to further improve the quality of the foam and its future price by lowering the amount of the blowing agent and nucleation catalysts, optimizing the foam density, and adjusting foam curing times.