STRUCTURE-PROPERTY BEHAVIOR OF GAMMA-IRRADIATED PHOSPHINIC ACID RESINS

The effect of high dose (1000-6000 kGy) gamma radiation on the chemica l and physical properties of the ionic polymer phosphinic acid resin h as been investigated. It was found that the resin irradiated to a dose of 1000 kGy shows a decrease in the acid capacity of about 8%, reachi ng 25% at 6000 kGy. In addition, the grain size of the resin particles was found to decrease with increasing irradiation dose, as was shown by SEM. The decrease in acid capacity was, however, accompanied by an improvement in the swelling properties. Furthermore, the effect of gam ma irradiation on the uptake of three different divalent metals, viz. Sr(II), Co(II) and Ni(II), by phosphinic resin was investigated and th e results were correlated in the usual manner of the distribution coef ficient (D). IR analysis of the resin confirms the occurrence of oxida tive degradation during gamma irradiation. Thermogravimetric analysis (TGA) of the resin showed that the thermal stability was affected by i rradiation. The kinetics of the thermal decomposition of the resin sho ws that the unirradiated resin and that irradiated to 2000 kGy follow a zero-order reaction, while the resin irradiated to doses up to 6000 kGy follows a first-order mechanism. The overall activation energies o f the different resin samples irradiated to different radiation doses were also determined. (C) 1997 Elsevier Science Limited.