ESR Study of Free-Radical Production in the Irradiation of Additive-Containing Polymethylmethacrylate

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Abstract
The free-radical density produced in polymethylmethacrylate under x-ray and γ-ray irradiation has been measured as a function of the amount and kind of organic additive substances present in the polymer. The ratio of radical density produced in the pure polymer by a given radiation dose to that produced in polymers containing additives exhibits a strong dependence upon radiation dose, unlike the similarly defined ratio for the protection against radiation damage by polymer chain scission. The time rate of decay of free-radical density was also found to depend upon the additives present. The existence of a radiation-dependent free-radical annihilation process is postulated.