Characterization and identification of synthetic paint materials used in modern and contemporary art : influence of UV light on the ageing process

Abstract

In this PhD thesis the chemical properties and UV ageing behavior of the most widely manufactured synthetic materials in the paint market and used in modern and contemporary art, i.e. as acrylic paints as well as two other types of polymeric materials such as polyvinyl acetates and alkyds were investigated. For this purpose a selection of pure synthetic materials but also mixed with different inorganic pigments, were properly prepared and arranged in the UV chamber for different periods of time.<br />For the identification and characterization of these samples before and after UV exposure, analyses with Pyrolysis gas chromatography mass spectrometry (Py-GC/MS) with the single-shot and double-shot mode were performed. Additionally, these analyses were complemented by Fourier transform infrared spectroscopy - attenuated total reflectance (FTIR-ATR), colour measurements, differential scanning calorimetry (DSC) and thermogravimetry (TG) analysis. Before UV exposure, the main composition of all synthetic materials was characterized by the complementation of all analytical techniques. By comparing UV-aged and non-aged samples clear variations as well as the formation of new peaks/products could be determined. For instance the double-shot technique of the Py-GC/MS allowed the detection of the effect of the photo-oxidative reactions in a more precise and detailed way than by the single-shot method. Additionally, with FTIR-ATR recorded newly formed products including unspecific aldehydes, lactones, and acidic oxidation products could be found and by colour measurements a substantial shifts of the a* and b* coordinates was detected. More pronounced differences were especially observed when the synthetic materials were in combination with pigments, i.e. paints.<br />