Depth-resolved FTIR focal plane array (FPA) spectroscopic imaging of the loss of melamine functionality of polyester melamine coating after accelerated and natural weathering

Abstract

FTIR-ATR (Focal Plane Array) FPA spectroscopic imaging was used to obtain depth resolved information about degradation of a polyester melamine coating by performing measurements on drilled conical holes. The results of the FTIR-FPA imaging show that combined effect of UV and moisture resulted in larger degradation effects in the outermost parts of the coatings but loss of melamine functionality was detected to the depth of approximately 8–10 μm after 2163 h weathering in QUVA accelerated test and after 4 years exposure in a marine environment. Longer periods of accelerated weathering, up to 4000 h, resulted in degradation through the whole coating outer layer.