Diffusion in Elastomers

Abstract

In this paper the various aspects of diffusion of matter in rubber are reviewed. Besides diffusion itself, attention has been given to the closely related subjects of solubility in and permeation through rubber of foreign matter. First, a survey is given of the fundamental background, including the most important mathematical equations required for an experimental approach to diffusion, the interpretation of measurements, and the application of available data to specific problems. The subjects discussed include furthermore: self-diffusion; diffusion, solubility, and permeation of gases, organic liquids, water, and solids such as sulfur and other compounding ingredients in and through rubber; temperature dependence of diffusion; effect of modification of the rubber by vulcanization, aging, crystallization, and addition of fillers; various technical problems such as diffusion in composite rubber or in porous rubber and separation by diffusion. It is shown that many facts concerning diffusion in rubber can be satisfactorily explained and even predicted from the molecular properties of rubber and the diffusing substance. Knowledge of diffusion moreover offers an opportunity of gaining an insight into the intermolecular forces of rubber and this may help to understand polymer behavior when other properties are concerned.