ABSORPTION DESORPTION HISTORY OF WATER AT 100-DEGREES BY POLYURETHANE FOAM

Absorption-desorption history of water at 100-degrees by polyurethane (PU) foam is determined either by experiment or by calculation. The kinetics of absorption and desorption with a one-dimensional transport are drawn as they are obtained from experiments and calculation, and the profiles of concentration expanded through the thickness of the PU sheet are calculated. The stage of absorption is described by transient diffusion with simple conditions and analytical solutions are successfully tested. The stage of drying is a more complex and necessitates the use of a numerical model. Absorption-desorption histories can thus be predicted by calculation when the diffusional parameters are known. Moreover, the first stage of absorption was found to be quite different from the following ones, the kinetics of absorption being slower for the first stage than for the other. Not only the diffusivity is lower for the first immersion, but the coefficient of matter transfer on the surface is finite for this first stage while it tends to infinity for the following ones.