A non-destructive technique, involving specimen encapsulation and determination of the dependence of thermal resistance on temperature, to measure the blowing agent pressure in cellular plastic insulation was recently presented. This technique was applied to a polyurethane foam manufactured with different blowing agents and the results were compared with those obtained from model calculations. The results indicate that the long-term solubility of the gas in the polymer matrix may differ from that determined from short-term experiments. The paper presents results for HCFC-123 and HCFC-141b as well as CFC-11 and discusses their im plication for long-term thermal resistance of polyurethane foams.
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