Study of free radicals in gamma irradiated cellulose of cultural heritage materials using Electron Paramagnetic Resonance

• Gamma irradiation is a safe option to stop fungi and insect attack of books.
• Proposed model fits statistically well.
• Model is useful to calculate order of reaction through EPR signal decay.
• Life of cellulose free radical can be predicted.
• CaCO3 presence did not affect EPR spectra of cellulose, neither the proposed model.
• Further studies of cultural heritage paper should consider low absorbed doses.

Main subject of this article was to study room temperature stable radicals in Co-60 gamma irradiated contemporary paper using Electron Paramagnetic Resonance spectrometer (EPR). XRD was used to study the effect of ionizing radiation on the morphology of book paper. SEM images presented regions with cellulose fibers and regions with particles agglomeration on the cellulose fibers. Those agglomerations were rich in calcium, observed by EDS. XRD analysis confirmed presence of calcium carbonate diffraction peaks. The main objective of this study was to propose a method using conventional kinetics chemical reactions for the observed radical formed by ionizing radiation. Therefore, further analyses were made to study the half-life and the kinetics of the free radical created. This method can be suitably applied to study radicals on cultural heritage objects.