The photooxidation and stabilisation of water-borne acrylic emulsions

The influence of light exposure on the photooxidative stability of aqueous acrylic based latices is examined by Fourier transform-infrared spectroscopy (FT-IR) and hydroperoxide analysis. These are based on emulsion polymerised formulations of methyl methacrylate and butyl acrylate. Hers acrylic latices based on different formulations are chosen as homo-polymers and copolymers. The nature of impurities and oxidation products generated during their manufacture are characterised and inter-related to their influence on subsequent photooxidative degradation. This involves the use of reflectance FT-IR spectroscopy to show functional group changes together with colorimetric UV analysis to determine photochemical generation of hydroperoxides, The early chemical changes and their subsequent influence on the physical and chemical properties of the latices during the later stages of photooxidation are found to exhibit a close inter-relationship. In terms of stabilisation co-reactive hindered piperidine stabilisers are found to be effective and none-extractable. However, the incorporation of simple terminal dialkyl acrylamide/methacrylamide groups are equally as effective. (C) 1997 Elsevier Science S.A.