Cycle of life: Estimating service life after film formation

PMSE 77

Stuart G. Croll, Stuart.Croll@ndsu.edu and Brian R. Hinderliter. Department of Coatings and Polymeric Materials, North Dakota State University, 1735 NDSU Research Park Drive, Fargo, ND 58105-5376
Once effort and control have been expended in applying a coating of the correct thickness and perfection, it must survive the rigors of the weather. Then the most difficult technological question becomes, - how long will it survive? Useful predictions of service lifetime have not previously been available and correlating performance in natural exposure using standardized, artificial exposures has proved problematic. Significant progress can be made through the realization that coating degradation occurs through many, repeated, random events. These are the incidence of ultraviolet photons, water molecules or polluting chemicals, etc. Thus one can use the statistics of random processes to generate estimates for degradation rate and use them in well-known and robust models for physical properties. In fact, one can separate the overall weathering degradation problem into smaller, component problems, i.e. unit processes, that may be addressed separately with suitable levels of detail.