Photodegradation of acrylic resins used in the conservation of stone

The photodegradative behaviour of a series of films of acrylic resins, unde r controlled conditions (RH = 50% and T = 25 degrees C) has been studied. F ilms of acrylic resins were applied both on a dolomitic white marble suppor t and on potassium bromide disks. The chemical evolution of the system has been followed by means of FT-IR spectra, HPLC-SEC, colour and water absorpt ion measurements. The main degradation pathway under ultraviolet irradiatio n is chain scission. The observed rates of photodegradation of the differen t resins may be related to the type of the ester group and to the presence of the alpha-methyl group in the main chain. (C) 1999 Elsevier Science Ltd. All rights reserved.