IMPROVEMENT OF FUNCTIONAL THERMAL CONDUCTIVITY OF POLYURETHANE FOAMS
Gas diffusion through the cell walls of rigid polyurethane foams, increases the K value of these products with time from about 18 mW/m degrees K after processing to nearly 29 mW/m degrees K. The research aims to achieve a significant improvement in the functional thermal conductivity of foams to 20 mW/m degrees K by inhibition of gas diffusion after reduction of the initial K value and without incurring a serious increase in manufacturing costs. The programme was in two parts. The first stage, using only commercial raw materials, studied the decrease in the initial thermal conductivity, lambda-o, measured 24 hours after processing, as well as the asymptotic value lambda-infinite. The influence of the type and amount of catalyst, surfactant, foaming gas, the amount of air, the polyol type was taken in account. In the second stage particular attention was given to modification of polyols to increase their diffusion barrier effect on polyurethane. Reductions of diffusion kinetics keeps the lambda-infinite value as a lower level. The minimal lambda-infinite got is 19.6 mW/m degrees K. Tests were made in industrial plants to check the results. Values of lambda-o and lambda-infinite can be reduced by formulation adjustment and by foaming process adaptation.
Bibliographic Reference: EUR 9226 FR (1984) MF, 58 P., BFR 120, BLOW-UP COPY BFR 290, EUROFFICE, LUXEMBOURG, POB 1003
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Record Number: 1989123119600 / Last updated on: 1987-01-01
Available languages: fr