Corrosion Potential Reduction of Phenolic-Based Cellular Plastic Insulation

J. Kosny
University of Massachusetts, Lowell,
United States

Keywords: cellular plastic foam, phenolic foam, building materials

Summary:

Cellular plastic foams are popular building and industrial thermal insulations around the world with well-established and cost-effective production methods. Among the conventional cellular plastics (such as expanded polystyrene (EPS), extruded polystyrene (XPS), polyurethane (PUR), polyisocyanurate (PIR)), phenolic foam is the only insulation that can reach a thermal resistivity greater than R-8 per inch (thermal conductivity < 0.0178 W/m-K). Furthermore, phenolic foams are inherently nonflammable, therefore, they satisfy the fire safety codes without the need for adding costly and high-health risk fire retardants. Sometimes, phenolic resins are also used as fire retarding additions in several other plastic products. Despite of many benefits, phenolic foam insulations are rarely used now in North American buildings, due to their corrosion potential, caused by a usage of strong acidic catalysts and poor mechanical characteristics, which led to nation-wide failures of metal roof decks during 1980-90s. This caused almost complete elimination of the phenolic foam from the North American building insulation market, with last production facility closed in 1991. It is important to notice that the acidity levels in phenolic foams produced in the past in the U.S., as well as in currently available foams in other countries worldwide, are quite high. This is reflected with low pH level in the range of 1.5-2.8. The above facts mobilized the joined research team from Fraunhofer CSE, University of Tennessee, Knoxville, Technical University of Lodz, Poland, and Atlas Roofing Corporation to develop, with financial support from U.S. DOE BTO and Fraunhofer USA, a new bio-based, less corrosive, mechanically stronger and less expensive type of phenolic foam. Our goal was to reduce the content of highly acidic catalysts (including sulphonic acid) in the phenolic foam and substitute them with less acidic and inexpensive catalysts. To address the corrosion issues associated with phenolic foam, the project team examined over 180 chemical formulations using variety of original acidic catalysts and additives. As a result, a novel phenolic foam formulation was developed with corrosion potential lower from the tap water. This presentation summarizes the development work, the results of laboratory and field exposure testing, and other outcomes of the series of works initiated in 2014 with the DOE BTO sponsored project “Development of a Bio-based, Inexpensive, Noncorrosive, Nonflammable Phenolic Foam for Building Insulation” performed under the Assistance Agreement No. DE-EE0006715, Building Energy Efficiency Frontiers and Incubator Technologies (BENEFIT).