Treatment and Processing of Leather Materials Using Gamma Radiation

This paper presents a review on the functionalization methods of leather materials using gamma radiation. There are few studies regarding the effects of gamma irradiation on leather materials while the majority of studies are on the irradiation of collagen for medical purposes, decontamination and preservation of heritage leather objects and parchment documents. Recent studies on leather and parchment treated with bigger doses then the sterilization or decontamination doses and on gamma irradiated collagen, new information about the solubility of collagen, crystalline structure, shrinkage temperature and mechanical properties were obtained. The relation between the shrinkage temperature and the gamma radiation dose absorbed by the material were investigated with the MHT (Micro Hot Table) method. Evidences of cross-linking of the collagen were found at doses up to 25 kGy while for doses of 50 kGy and more the principal process was the scission of the peptide chains. The mechanical properties of tanned leather and parchment such as tensile strength and elongation at break were studied. The parchment tensile strength decreases with the increase of absorbed dose, for doses bigger than 10 kGy. The behaviour of tanned leather is different, an increase in the tensile strength at doses up to 25 kGy which can be a threshold for collagen cross-linking. More evidence of cross–linking of the collagen fibrils in leather materials were shown with the SEM-EDX and TG investigations. There were no substantial modifications in the structure of collagen for doses of 5, 10 and 15 kGy as shown by the SEM and TG analysis, but a slightly smaller loss of mass in the case of the dose of 25 kGy which can prove the cross-linking of collagen in the tanned leather material. Based on literature review a conceptual application model for gamma irradiation on leather materials was elaborated.