The photostability and peel strength of ethylene butyl acrylate copolymer blends for use in conservation of cultural heritage

Materials, both natural and synthetic, are used as adhesives or consolidants during the conservation of cultural objects. However, few adhesives have been formulated specifically for the needs of cultural heritage. This article describes a study of the stability of ethylene butyl acrylate copolymers as well as blends of these polymers with low molecular weight resins, which may be used as consolidating adhesives for flaking and fragile paint layers. The materials were aged under simulated museum conditions. Fourier-transform infrared spectroscopy and size exclusion chromatography were used to analyze changes in chemical structure and molecular weight distribution, respectively. The degree of degradation was found to be dependent on the specific blend composition. With the addition of a hindered amine light stabilizer, minimal changes occurred in the molecular weight distribution and no loss in polymer solubility were noted. Therefore, it is suggested to incorporate a stabilizer into ethylene butyl acrylate polymer blends to extend their life and safe use in cultural heritage. Differential scanning calorimetry was employed to investigate the miscibility of the binary blends and the temperature window of their application. Furthermore, adhesive peel strength for the individual components and the binary mixtures revealed values comparable to that of Paraloid™ B-72, a frequently used consolidant. Consolidation tests on the blends were done by professional conservators on mock up and dummy paintings.