4.5 Electron Spin Resonance Studies of Photo-Oxidation and Photo-Decomposition of Polymeric Coatings Used in the Conservation of Antiquities
University of London
The Getty Conservation Institute
G. V. Robins
William S. Ginell
Period of Activity: 6/86 to 6/87
Electron spin resonance was employed to examine the photochemical aging of poly(vinyl acetate) (PVAc) resins.A final report was submitted entitled "Studies of Poly(Vinyl Acetate) Coatings Used in the Conservation of Antiquities with Electron Spin Resonance Spectroscopy." These data were principally contracted for GCI in-house research on coatings.
Robins, G.V., "Studies of Poly(Vinyl acetate) Coatings Used in the Conservation of Antiquities with Electron Spin Resonance Spectroscopy," Final Report to the Getty Conservation Institute, June 1987.
ABSTRACT-Studies of the UV photolysis of PVA films with electron spin resonance (ESR) spectroscopy uncovered an extensive free radical growth and decay profile which preceded any chemical change such as photo-oxidation. This activity was centered around the production and decay of a strong quartet 'marker' signal which is tentatively assigned to a free radical formed by chain breaking. As evidenced by the lack of chemical change observed, the constraints of chain geometry indicate that radical recombination and regeneration on further UV excitation is more likely in the first place than combination with oxygen to form oxidation products.