Evaluation of accelerated weathering tests for three paint systems: a comparative study of their aging behaviour

The evolution of an epoxy-acrylurethane, alkyd and chlorinated rubber paint s was studied under five standard artificial tests. The chemical evolution was followed through IR spectra; the variation in physical properties was s tudied from Vickers microhardness readings and gloss measurements. It was s hown that the chemical evolution controls the loss of physical properties. However, the behaviour of the three paints towards the artificial weatherin g factors is tremendously different. While the chemical degradation of the alkyd and acrylurethane top coats were described in a previous paper [5], t he degradation of the chlorinated rubber paint was found to mainly involve chlorinated rubber and the chlorinated paraffins (plasticiser) through dehy drochlorination and photooxidative processes. Carbonyl growth is directly r elated to the UV light dose received by the samples. However, the standard NFT30049 test including SO2 atmosphere exposures causes degradation chemist ry that does not occur in the other test cycles. (C) 2001 Elsevier Science Ltd. All rights reserved.