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Abstract
Fluorocarbon blowing agents are used for the manufacture of thermoset and thermoplastic foam insulations. The effectiveness of the insulation depends upon several properties and the chemical type, density, cell size, number of closed cells and the chemical composition and concentration of the gases contained in the cells. In particular, the low thermal conductivity of the foam is dependent upon the concentration of the fluorocarbons captured by the closed cell structure. This thermal efficiency of the foam deteriorates with age by the ingress of air and slower engress of the fluorocarbon. Thus analytical procedure which quantify the fluorocarbon cell gas concentration (and that dissolved in the solid polymer phase) at any point in time, enalbes the thermal and mechanical performance of insulating foams to be better understood, leading to performance improvements which would extend the utility of the foam end-use applications. In addition to understanding insulation effectiveness and diffusion processes, the same data could assist in explaining other polymer-blowing agent interactions and improve process economics by material balance analysis. This paper describes two methods developed by DuPont Canada to determine the concentration of CFC and HCFC in thermoset and thermoplastic foams. One method suitable for thermoplastic foams only, has been used at DuPont for several years. The second method applicable to both thermoset and thermoplastic foams is in a development stage, but appears to give flurocarbon concentration results consistent with thermal conductivity measurements, especially for thermoset foams. Outlines of both procedures, appratus and some data are presented with future research to improve the techniques.
Fluorocarbon blowing agents are used for the manufacture of thermoset and thermoplastic foam insulations. The effectiveness of the insulation depends upon several properties and the chemical type, density, cell size, number of closed cells and the chemical composition and concentration of the gases contained in the cells. In particular, the low thermal conductivity of the foam is dependent upon the concentration of the fluorocarbons captured by the closed cell structure. This thermal efficiency of the foam deteriorates with age by the ingress of air and slower engress of the fluorocarbon. Thus analytical procedure which quantify the fluorocarbon cell gas concentration (and that dissolved in the solid polymer phase) at any point in time, enalbes the thermal and mechanical performance of insulating foams to be better understood, leading to performance improvements which would extend the utility of the foam end-use applications. In addition to understanding insulation effectiveness and diffusion processes, the same data could assist in explaining other polymer-blowing agent interactions and improve process economics by material balance analysis. This paper describes two methods developed by DuPont Canada to determine the concentration of CFC and HCFC in thermoset and thermoplastic foams. One method suitable for thermoplastic foams only, has been used at DuPont for several years. The second method applicable to both thermoset and thermoplastic foams is in a development stage, but appears to give flurocarbon concentration results consistent with thermal conductivity measurements, especially for thermoset foams. Outlines of both procedures, appratus and some data are presented with future research to improve the techniques.
Date
9/1989
9/1989
Author(s)
M R Ascough
M R Ascough
Page(s)
16
16
Keyword(s)
cellular plastic; blowing agent
cellular plastic; blowing agent