Effect of glycerol triglycidyl ether on the dimensional stability and flexibility of photographic gelatine films

AbstractThe gelatine emulsions used in historical photographs can shrink and become brittle under alternating dry–wet environmental conditions, which would result in curling and fracture of the gelatin paper photographs, thereby degrading their quality and threatening the long-term inheritance of such cultural heritage. To improve the stability and flexibility of gelatine films under dry–wet cycling, glycerol triglycidyl ether (GPE) was employed as a synergistic crosslinking and plasticising agent. The plasticising effect of GPE on the dimensional stability and flexibility of gelatine films in alternating dry–wet environments was firstly studied. Gelatine films with different contents of GPE were prepared and their dimensional changes during dry–wet cycling were investigated. The results indicate that GPE greatly enhances the dimensional stability of the films during cycling. By analysing the swelling behaviour, molecular structure, mechanical strength, fracture cross-sections, and other properties of the gelatine–GPE films, it was confirmed that the addition of GPE greatly reduces the moisture absorption and swelling of gelatine and improves its moisture stability. Furthermore, benefiting from GPE as a crosslinking agent, the mechanical strength and flexibility of the gelatine films were both enhanced. In this study, the modification of gelatin film by GPE provides experimental evidence for the subsequent research on the application of restoration and conservation for the gelatin paper photographs.