Reconstruction and repair of ceramic and glass artifacts has long been a central part of art conservation in museums around the world. Rejoining fragments into whole artifacts is important to understanding the original function of artifacts and for providing meaningful displays with which to educate the public. Polymeric adhesives, such as acrylics and epoxies, can be successfully used to join fragments together, but are difficult to remove making correction of reconstructive errors difficult and leaving polymeric contamination to interfere with future microscopic and chemical analyses of the artifacts. The objective of this project is to study the use of thermally- and photochemically reversible epoxies as adhesives that can be use to bond fragments together, but that can be reworked or even removed entirely with minimal adverse affects. These epoxies are composed of a liquid epoxy resin and a liquid curing agent that react to afford a highly cross-linked polymer with the same mechanical properties of traditional epoxies. However, whereas traditional epoxies irreversibly cure into an intractable material, these epoxies will have thermal or photochemical weak-links built into every resin component that will allow for their triggered conversion with exposure to heat (> 90 °C) or ultraviolet light back into liquid constituents. The thermal weak-link will be the Diels Alder cycloadduct of a maleimide and furan that is known to form at room temperature but reverts to its constituents at temperatures above 90 °C. The photochemical weak-link will be the cyclodimer of a coumarin derivative that forms with exposure to long wave ultraviolet and is cleaved by shortwave ultraviolet light. The epoxy adhesives built with these weak-links will be used to bond glass or ceramic fragments together. Mechanical testing will be conducted to compare these materials with commercial epoxy adhesives then the thermal or photochemical degradation of the adhesive bonds and the efficacy of removing the oligomeric residues will be evaluated.
NON-TECHNICAL SUMMARY:
This project is directed at development and application of new adhesives that can be used to repair artifacts or assemble fragments into whole pieces, but can be readily removed by heating above 90 °C or with exposure to ultraviolet light. Restoration and preservation of art and artifacts often requires adhesives, but many are difficult, if not impossible to remove without damaging the artwork that it was meant to preserve or repair. This project will include the development of the thermally or photochemically removable adhesives and testing their application as adhesives to join ceramics and glass and demonstration the reversibility of the adhesive bonding with the application of heat or light. Success will provide a new, important tool for conservators and museums for repairing or reconstructing artifacts. These removable adhesives will also prove valuable to any application needing a high performance adhesive that can readily removed or reset, including microelectronics manufacturing, aerospace composites, and medical prostheses.
