A mechanistic study of degradation of a typical automotive clearcoat caused by bird droppings
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This study aims at investigating the degradation mechanism of an automotive clearcoat caused by bird droppings. Natural bird droppings and their synthetic equivalent (pancreatin) were utilized for this purpose. The presence of highly-etched areas on the surface of coatings and structural variations of clearcoat after being attacked by these materials corresponded to a catalyzed hydrolytic degradation. This finding was obtained using different analytical techniques. Based on these studies, three possible hypotheses were presented, including acid catalysis, metal ion catalysis, and enzymatic catalysis. The conditions required for the occurrence of each hypothesis were discussed. It was found that acid and metal ions have a weak contribution to catalyze the hydrolysis reaction of clearcoat, whereas enzymes existing in bird droppings were mainly responsible for this hydrolytic degradation.
KeywordsEnzymatic degradation Bird droppings Automotive coating Hydrolysis Pancreatin
The authors thank the Iran Khodro Co., for providing the coating samples.
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