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Field experience has shown that facer delamination, or more accurately, foam failure in the near facer region, occurs in polyisocyanurate insulated roofing systems. This paper examined the conditions which may lead to foam failure in the near-facer region, defined here as the first two to seven cell layers of foam from the facer. The study examines delamination in faced polyisocyanurate (PIR) foam boards. These boards were blown with blowing agents including CFC-11 and HCFC-141b. The samples were tested before and after in-service exposure. Tensile strength and Young's modulus were determined as was the site of foam failure. Light microscopy was used to analyze the near-facer region both before and after failure and to determine the aspect ratio in the foam. Failure was found to occur in the near-facer region in all faced samples tested. Failure occurred in the faced foams at one half the stresses found in the unfaced samples. Additionally, the samples were found to have distinctly different tensile strengths near the upper facer than in the bulk of the foam.
aspect ratio, building technology, blowing agents, field exposure, insulation, low-sloped roofs, mechanical properties, polyisocyanurate foam, roof, temperature exposures
Project Manager, Law Engineering, Inc., Chantilly, VA