GAMMA-RAY-INDUCED MODIFICATIONS OF THE CHEMICAL-STRUCTURE OF AN ION-EXCHANGE RESIN

Gamma-ray irradiation of ion exchange resins used for processing nucle ar effluent may lead to considerable modifications of the molecular st ructure and macroscopic properties. In the present study, crosslinked poly(4-vinylpyridine) (P4VP), irradiated by a Cs-137 gamma-source up t o an integrated dose of 14 400 kGy, has been investigated. The particl e-induced desorption-mass spectrometry (PDMS) technique is able to det ect the radiation-induced structural degradation of such an infusible and insoluble material. From the results of PDMS, a coherent descripti on of the production of specific radical fragments and modified chains is proposed. Both the nature of these fragments as well as their form ation, as a function of the dose of irradiation, correlate with result s of electron paramagnetic resonance spectrometry and Fourier transfor m infrared spectroscopy, and with thermogravimetric and dynamical mech anical analysis. In addition, analysis of the soluble and insoluble fr actions helps to discriminate between different possible processes. In particular, it is shown that the loss of pyridine fragments correlate s well with chemical measurements like the loss of protonatable sites. (C) 1997 Elsevier Science Limited.