Some aspects of the crosslinking and degradation of gelatin molecules in aqueous solution irradiated by ⁶⁰Co γ‐rays

Abstract

Abstract When an aqueous gelatin solution was irradiated by γ‐rays from a Co 60 source, crosslinking occurred if nitrogen gas was passed through the solution, while degradation occurred with irradiation in an oxygen atmosphere. Empirical equations for the changes of the viscosity and the number of inter‐ or intramolecular crosslinks were obtained in each case and the phenomena were explained on the basis of an assumed reaction mechanism. The general equation for crosslinking is [η] = [η] O e kar , where [η] represents intrinsic viscosity of the solution and r is the γ‐radiation dose. The number of inter‐molecular cross links [R‐R] inter is given by [R‐R] inter = N 0 (1 ‐ e ‐kr ), and the number of intramolecular cross links by [R‐R] intra = N 0 (kr + e ‐kr ‐ 1), where N 0 is the initial number of gelatin molecules. In the case of degradation, the variation at intrinsic viscosity and the number of intermolecular cross links with radiation dose is given by the equations: [η] = [η] 0 [ N 0 /( N 0 + k ′ r )] a and [R—R] inter = − k′r .