AN INVESTIGATION INTO THE CATHODIC DELAMINATION OF UNPIGMENTED CHLORINATED RUBBER FILMS

A study of unpigmented chlorinated rubber protective coatings used under cathodic protection conditions in a simulated marine environment has been made. The generation of an alkaline environment at the coating-metal interface leading to a degradation of the coating and to subsequent failure as a protective film has been demonstrated. This degradation has been shown to be essentially mechanical in nature, arising from both inherent defects in the film and from accidental mechanical damage, rather than chemical. It has been shown that the transport pathways for ions through these films involve the ions moving through interconnected aqueous cracks and crevices rather than through the homogeneous bulk of the membrane.