This past January, Fraunhofer CSE was selected by the U.S. Energy Dept. Building Technology Office to develop a new bio-based phenolic foam to be used in building insulation.
Working with partners from the University of Tennessee, Knoxville and Atlas Roofing Corporation, Fraunhofer CSE researchers are in the process of developing a non-corrosive, non-flammable, inexpensive phenolic foam derived from bio-based components to be use in building applications (e.g. building insulation). To produce the proposed foam, the project team is making the following components a major part of the production strategy:
- Lignocellulose Structure: Light-weight nanocellulose fibers will be added to mechanically reinforce the foam matrix.
- Reduction of Foam Acidity: Minimize the use of highly acidic sulphonic acid catalyst by substitution with less acidic, bio-based, and inexpensive organic acid catalysts. Target a pH ≥ 4.5.
- Thermal Performance Enhancement: Thermal radiation to be suppressed by using inexpensive infrared opacifiers and reflective foil.
Currently, the project team has produced samples using a variety of catalysts, sufactants, curing times, blowing agents, and nanofillers (e.g. nanocellulose). The most recent samples have a pH ≈4.5-5, achieving the pH target set at the beginning of the project, and a thermal performance of R-4 per inch.
When phenolic foam was first in use, it had a pH ≈2-2.5, which made the foam more acidic and ultimately lead to the corrosion of metal roofs when the foam came in contact with moisture. If the project team is successful, a new bio-based foam with a higher pH value will provide the building industry with an innovative option for insulation applications.
Future work will include continued attempts to reduce the acidity of the foam by lowering the catalyst amount and adjusting curing times.