Paraloid ® is one of the most frequently used acrylic polymers, employed mainly for its adhesive and consolidating properties in the conservation of a wide range of materials. Appreciated for its reversibility, mechanical characteristics and ease of use, application of the polymer requires it to be simply dissolved in a solvent. Nevertheless, the chemical nature of the relevant solvent must be regarded as an essential parameter, due to its influence on the physico-chemical characteristics of the resulting adhesive film. The aim of this study was to evaluate the effect of the solvents used with Paraloid ® acrylic resin on adhesive film properties, and more specifically on their thermophysical characteristics. Two compounds used in conservation (Paraloid ® B72 and B44) and six solvents (ethanol, acetone, ethyl acetate, ethyl lactate, butyl acetate and toluene) were used to make adhesive film replicates. Thermogravimetry and differential scanning calorimetry (DSC) analyses allowed us to determine the value of the glass transition temperature (Tg) of solvent/Paraloid ® mixtures. Mass monitoring of the films enabled us to correlate Tg values with the quantity of residual solvent. Results showed that all the solvents remained present for a long time in Paraloid ® films when drying took place at room temperature. Moreover, DSC analysis highlighted the fact that residual solvent had a considerable impact on the value of film Tg. In fact, residual solvent significantly lowered the Tg value of Paraloid ® (by up to 30 °C below its theoretical value). This underlined the importance of taking the impact of solvent on resin properties into account.
International audienceThe use of the lasers Q-switched Nd:YAG to remove the dust of the stone monuments especially sculpture gradually replaces the more abrasive technique of sandblasting. This tendency made us consider the lasers as solution for the cleaning of ceramics and the plasters. Indeed in museums, these materials are often covered with dirty mark (dust, grease, etc.) which is difficult to remove without damaging the object. This paper deals with the impact of different types of lasers (Nd:YAG first and third harmonic) irradiation on plaster and with the effects on its morphology and its crystallography. Plaster is an interesting material because of its typical acicular crystals altered at low temperature. That is why synthesis samples were prepared, constrained in temperature then analysed by various processes (SEM, XRD, TGA. . . ). These results were compared with samples cleaned by laser. That enabled us to conclude that plasters cleaned by UV-laser (third harmonic of the Nd:YAG) underwent neither yellowing, nor morphological or crystallographic changes. It has to be opposed to the intense yellowing, and sometimes morphological destruction, which appears with an infrared wavelength (first harmonic of the Nd:YAG)
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.