Characterization of Polymers and Corrosion Products by Raman Spectroscopy

Abstract

The Raman spectroscopy is a nondestructive lateral surface sensitive analytical technique aimed at characterizing newly developed coatings and examining the quality of corrosion resistance of surface modifications. Due to the small spatial detection volume of 1 μm3, the chemical microstructure of the surface and organic or inorganic layers can be identified. The crystallinity of coatings, the degree of molecular order, orientation and cross-linking, measurable by the stereo selectivity of the Raman spectroscopy was applied for the classification of Polyethylenetherephtalate (PET) coatings. For determining multilayer systems, the confocal measuring technology of the Raman microscope has been performed for depth profiling through transparent PET layers. Furthermore, this confocal measuring technique provided the best results for the local identification of corrosion products by monitoring the corrosion under transparent organic corrosion protection layers. Selected samples displayed the facilities of Raman spectroscopy to characterize the formation of organic surface coatings and inorganic contaminations by lateral and confocal detection properties. Therefore, Raman spectroscopy received special interest in coating and steel applications to analyse the degradation, processing history or interlacing of coatings and to reduce production sources of error.