Researcher(s)
- Gavin Brownstein, Chemical Engineering, University of Delaware
Faculty Mentor(s)
- Norman Wagner, Chemical and Biomolecular Engineering, University of Delaware
Abstract
Gels can facilitate controlled solvent release when working with moisture sensitive media in art restoration and conservation. Hydrogels consist of a solid polymeric network phase swollen by an aqueous solution. Agar is a polysaccharide that can form a brittle gel that has previously been used in art conservation. Xanthan gum and konjac glucomannan are polysaccharides that exhibit synergistic gelation to form a highly elastic gel. Xanthan-konjac-agar (XKA) mixed gels form an interpenetrating network of the two previously mentioned gels which shows promise as a strong elastic gel capable of removing contaminants from surfaces. The objective of this research is to measure the mechanical properties of XKA gels and relate them to the effectiveness of these gels in art conservation. Yield stress and dynamic modulus values were measured using oscillatory strain and frequency sweeps and their gelling and melting behavior were explored through monitoring the moduli during heating and cooling. Contaminant removal and residues left by the gels were tested on paper, ceramic, and painted media and measured visually with UV luminescence. Relative to the composition of polymeric components in the gels, the yield stress at high frequencies and the elastic modulus decreased when the concentration of agar increased. The effects of ionic bonding through the addition of calcium acetate were also investigated. Adding 0.4 g/L calcium acetate resulted in a decrease in elastic modulus, a decrease in the temperature at which the gels begin to melt, and an increase in yield stress. While XKA hydrogels demonstrated syneresis on paper media after being left for extended times, soaking the XKA gels in a dilute acetone solution proved capable of removing common adhesives and varnishes from target areas of ceramic and painted pieces.