Structure—property behaviour of gamma irradiated phosphinic acid resins

Abstract

The effect of high dose (1000–6000 kGy) gamma radiation on the chemical and physical properties of the ionic polymer phosphinic acid resin has 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%, reaching 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 gamma irradiation on the uptake of three different divalent metals, viz. Sr(II), Co(II) and Ni(II), by phosphinic resin was investigated and the results were correlated in the usual manner of the distribution coefficient ( D). IR analysis of the resin confirms the occurrence of oxidative degradation during gamma irradiation. Thermogravimetric analysis (TGA) of the resin showed that the thermal stability was affected by irradiation. The kinetics of the thermal decomposition of the resin shows that the unirradiated resin and that irradiated to 2000 kGy follow a zeroorder reaction, while the resin irradiated to doses up to 6000 kGy follows a first-order mechanism. The overall activation energies of the different resin samples irradiated to different radiation doses were also determined.