Evaluation of cellulose paper degradation irradiated by an electron beam for conservation treatment

Abstract

In this study, we investigate the chemical, physical and optical properties of cellulose paper irradiated by an electron beam for disinfection. Cellulose chain scission and oxidation induced by radiation increased considerably at 25 kGy irradiation, whereas folding endurance, morphology, and crystallinity did not undergo significant changes. The cellulose chain scission rate of paper irradiated under air-dried and wet conditions showed no difference; however, cellulose oxidation increased to a higher degree in paper irradiated under wet conditions than under air-dried conditions. Electron beam irradiation did not significantly affect changes in paper color, which is associated with oxidation. However, when irradiated papers were aged, the color difference increased according to the irradiation dose, as the oxidized functional groups of cellulose can act as a trigger for color change. A linear relationship between the cellulose chain scission rate and irradiation dose was found; thus, the cellulose chain scission rate can be predicted for a specific dose. The degree of polymerization was calculated from the predicted cellulose chain scission rate using the Ekenstam equation. According to the prediction, the degree of polymerization decreased to 74% at a dose of 5 kGy, a suitable dose for paper disinfection. In the low-dose range, electron beam irradiation did not adversely affect the physical properties of paper, but significant changes occurred in both the chemical and optical properties of paper. Thus, electron beam irradiation may be of use in disinfecting severely degraded paper due to biological factors; however, the irradiation process diminishes paper permanence. Graphic abstract: [Figure not available: see fulltext.].