Biobased, Non-Corrosive, Nonflammable Phenolic Foam Insulation

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Research Motivation

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:

  • One of the highest thermal insulation of any building insulation
  • Only plastic foam insulation used in buildings that is inherently fire resistant
    • Excellent ignition resistance and low fire spread
    • Does not require an addition of high health-hazard fire retardants in its chemistry which are otherwise used in other conventional foam insulations
    • Does not produce toxic fumes when burnt

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 By late 1990s, the phenolic foam was completely withdrawn from the U.S. building insulation market.

A New, Non-Corrosive, Nonflammable Phenolic Foam

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.

Sustainable Production of Biobased Components for Phenolic Foam

As part of this DOE-sponsored work, we also developed novel biobased phenolic foam formulations that were derived from lignocellulose and bio-oil:

  • Lignin and pyrolytic oil as a source of phenol
  • Non-formaldehyde chemistry that gives advantage over formaldehyde-containing chemistry of mineral wool, polyisocyanurate etc.


Jan Kośny, Ph.D.
Director, Building Enclosures and Materials
Office +1 (617) 714-6525