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MORPHOLOGICAL CHANGES IN POLYURETHANE COATINGS ON EXPOSURE TO WATER. (R828081E01)
Citation:
Yang, X. F., D. E. Tallman, S. G. Croll, AND G. P. Bierwagen. MORPHOLOGICAL CHANGES IN POLYURETHANE COATINGS ON EXPOSURE TO WATER. (R828081E01). ANALYTICA CHIMICA ACTA. American Chemical Society, Washington, DC, 77(3):391-396, (2002).
Description:
When a polyurethane self-priming coating on a sol-gel treated aluminum panel was immersed in dilute Harrison's solution, subsequent change of the polyurethane coating surface was inspected with atomic force microscopy (AFM) and scanning electron microscopy (SEM). After immersion, filiform threads formed in the coating surface. The mechanism suggested for the formation of filiform structures is that when the solution penetrates into the coating, osmotic cells form under the surface layer of the coating. The formation of these osmotic cells may be caused by the existence of soluble impurities in the coating and these soluble impurities concentrate in the solution and promote water adsorption into the coating. As a result, blisters form on the surface, especially at flexible, loosely cross-linked locations. The combination of blisters appears as filiform structures on the coating surface.
Author Keywords: Coating degradation; AFM; SEM