Permeability of polymers in protective organic coatings

Metals like steel undergo corrosion over a period when exposed to atmosphere. Because of their low cost, versatility and aesthetic attributes, organic coatings are the natural choice for corrosion protection. The exact mechanism by which these coatings retard the corrosion reaction is not yet fully understood. However, it is the barrier nature of polymer to the passage of oxygen and water, which is responsible for corrosion protection. Barrier nature of a polymer and its relation to the structure of polymer is extensively studied and successfully exploited in other areas like membranes, packaging. However, such a systematic study in the area of coating is not yet reported. This article reviews the relationship between structure of polymer and its permeability to oxygen and water. Detailed study of such correlation will enable selection of the polymer for required protective action. (C) 2003 Elsevier B.V. All rights reserved.