Thermal Treatment of a Commercial Polycyanoacrylate Adhesive Addressed for Instant Glass Restoration, for Investigating Its Ageing Tolerance

Abstract

In the present study, the results of an experimental work on the thermal endurance and decomposition products of the commercial restorative adhesive Loctite® Super Attak Glass, being applied on glass surfaces, are presented. The clarity of the cyanoacrylate polymer and its rapid anionic polymerization reaction are outcomes of the chemistry of the monomer and its activity. First, evaluation of the reversibility of this glue was examined through the solubility tests. It was verified that the adhesive is reversible since it is diluted in several solvents. Later, by applying pyrolysis conjugated with gas chromatography and mass spectrometry (Py–GC/MS), the thermal profile of the polymer is recorded in its neat form and in its aged state (weathered under the influence of UV-irradiation or thermal treatment at 50 and 75 °C). The decomposition products are detected and identified and, finally, possible reactions are investigated. Emphasis is placed on those that could be considered harmful to cultural heritage materials and objects. The fragments by the pyrolytic reactions identified mainly concern esters, less aldehydes and alcohols, small nitrogen compounds, and in some cases unsaturated hydrocarbons with higher molecular weight. Additives such as radical polymerization inhibitors and stabilizers, as well as some plasticizers, were also detected.

Keywords

• cultural heritage
• anionic polymerization
• reversible restoration
• photooxidation
• pyrolysis
• Loctite^® Super Attak Glass