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Abstract
Clossed cell foams filled with high molecular weight blowing agents, e.g., CFCs have the highest thermal resistivity of any conventional insulation. When it is first manufactured, one half of the heat transfer is due to conduction through the gas in the cell interior. If the foam surface is not well sealed, air components diffuse into the foam over time and the blowing agent diffuse out. This aging process can cause a substantial reduction in the thermal performance of the insulation. The aging process of the foam can be predicted based on recent measurements by the authors of the diffusion coefficient for a range of polyurethane & polyisocyanurate foams. These measurements and subsequent predictions will be used to evaluate varoius techniques to rapidly determine the long term aging behavior of foams. The time required, as well as the accuracy of the techniques, will be dealt with. The advantages of advanced facers or seals for the principal surfaces of the foams will be demonstrated, e.g., a carbon dioxide-filed foam board protectyed by an ideal facer is shown to give a time-averaged behavior equivalent to a CFC- or HCFC-filled foam whose surfaces are unprotected.
Clossed cell foams filled with high molecular weight blowing agents, e.g., CFCs have the highest thermal resistivity of any conventional insulation. When it is first manufactured, one half of the heat transfer is due to conduction through the gas in the cell interior. If the foam surface is not well sealed, air components diffuse into the foam over time and the blowing agent diffuse out. This aging process can cause a substantial reduction in the thermal performance of the insulation. The aging process of the foam can be predicted based on recent measurements by the authors of the diffusion coefficient for a range of polyurethane & polyisocyanurate foams. These measurements and subsequent predictions will be used to evaluate varoius techniques to rapidly determine the long term aging behavior of foams. The time required, as well as the accuracy of the techniques, will be dealt with. The advantages of advanced facers or seals for the principal surfaces of the foams will be demonstrated, e.g., a carbon dioxide-filed foam board protectyed by an ideal facer is shown to give a time-averaged behavior equivalent to a CFC- or HCFC-filled foam whose surfaces are unprotected.
Date
12/1992
12/1992
Author(s)
L Glicksman; M Page
L Glicksman; M Page
Page(s)
81-90
81-90
Keyword(s)
closed cell insulation; CFC; thermal resistance; aging process
closed cell insulation; CFC; thermal resistance; aging process