Dose-Dependent Effects of Gamma Irradiation on Collagen in Vegetable Tanned Leather by Mobile NMR Spectroscopy

The dose dependent effect of gamma irradiation on collagen in vegetable tanned leather was studied by unilateral nuclear magnetic resonance (NMR). Examination of the irradiated samples after 1 week of treatment revealed variations of both spin-lattice (T1) and spin-spin (T2) proton relaxation times. To evaluate the long-term effects of gamma irradiation, the irradiated samples were further exposed to accelerated ageing at 40°C and weekly alternate 30% and 75% relative humidity (RH) for 12 weeks. The synergistic action of temperature and relative humidity caused distinct variations of both T1 and T2 relaxation times suggesting distinct modifications within the collagen fibril structure. Structural variations were attributed to cross-linking, the prevalent pattern at 25 kGy dose, while polypeptide chain scission was shown to be prevailing at higher doses.