Water action on plastics

Water is part of our natural environment, and therefore of that of most of the materials we use. The effects of a humid environment on the corrosion of metals have been known for a long time, but when it comes to polymeric materials, the picture is often less clear: these effects can be more subtle and long-term (several years), and their mechanisms can be diverse (physical or chemical). We thought it would be interesting to take stock of this subject for at least two reasons. Firstly, the development of high-performance composite materials, particularly those with polyepoxide matrices, has led to the emergence of new, hitherto unknown problems associated with differential swelling under transient diffusion conditions, which call for new experimental and theoretical approaches. Secondly, we are beginning to gather the fruits of studies generally carried out in the 1970s on the long-term behavior of materials often referred to as engineering plastics, and featuring structures liable to undergo hydrolysis: polyamides, polyurethanes, linear polyesters and cross-linked polyesters, polycarbonates, poly(amide-imides), polyimides, and so on.

We'll look in turn at physical and chemical aging due to water.