The Sorption of Water by Rubber

Abstract

In the absence of air the absorption of water by a vulcanized crepe rubber tends to an equilibrium value in accordance with an osmotic mechanism of absorption. An equation for absorption as a function of time, derived by consideration of such a mechanism, represents the experimental data adequately. A relationship may be derived from the basic rate equation, correlating equilibrium absorption with ambient vapor pressure. This equation also gives good agreement with the experimental data. The divergence from the theoretical relationship found for absorption in the presence of air may be attributed to oxidative aging of the rubber. This effect is most marked at elevated temperatures, where the results of absorption under nitrogen are very much lower than those for absorption in the presence of air.