ABSORPTION DESORPTION HISTORY OF WATER AT 100-DEGREES BY POLYURETHANEFOAM

Absorption-desorption history of water at 100-degrees by polyurethane (PU) foam is determined either by experiment or by calculation. The ki netics of absorption and desorption with a one-dimensional transport a re drawn as they are obtained from experiments and calculation, and th e profiles of concentration expanded through the thickness of the PU s heet are calculated. The stage of absorption is described by transient diffusion with simple conditions and analytical solutions are success fully tested. The stage of drying is a more complex and necessitates t he 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 differe nt from the following ones, the kinetics of absorption being slower fo r the first stage than for the other. Not only the diffusivity is lowe r for the first immersion, but the coefficient of matter transfer on t he surface is finite for this first stage while it tends to infinity f or the following ones.