Radiation Kinetics in Anthracene-Silicone Mixtures

The yield of radicals produced in radiation-induced reactions in simple organic compounds has frequently been studied by incorporating low concentrations of an additive capable of acting as a trap for the radicals produced. The present paper extends previous work on compounds of low molecular weight into the field of polymers. The removal of anthracene in polydimethyl siloxane fluids is studied as a function of concentration, dose and intensity. The results obtained show a fundamental difference from those previously found in anthracene-cyclohexane solutions in that there is little dependence on radiation intensity. The earlier theory, according to which there is competition between radical-radical and radical-anthracene combination is therefore not tenable in the present system. An alternative theory according to which reactions of active centres occur, either with the neutral environment or with anthracene molecules, is consistent with the observed data. Values for the reaction constants are derived.