Spectroscopic study of acrylic resins in solid matrices

The degradation of the acrylic polymers, usually used as protective coatings in porous materials of artistic interest, determines depolymerization and/or cross-linking processes dangerous for the ‘protected’ materials. Three types of largely used commercially products have been applied as thin films on different specimens; their aging, induced with an exposition to a Xenon lamp, has been monitored with UV-VIS fluorimetry, microRaman and ATR (Attenuated Total Reflectance) techniques. The fluorimetric properties of the acrylic polymers make possible the application of the reflectance fluorescence for the control of cleaning procedures and for the monitoring of the conservation of the art objects. The microRaman technique is here used for the first time for the characterization of these coatings, giving the possibility to examine surfaces of order of magnitudes of microns. The comparison of the microRaman results with the ATR ones, gives a good, initial picture of the existing degradation processes, allowing to follow the evolution of some chosen vibrational bands, directly related to the changing of the molecular structure.