Trapping and detrapping of radiation-induced charge carriers in polymethylmethacrylate (PMMA), polyvinyl chloride (PVC), and several other polymers were investigated. Thermoelectric currents were generated in the polymers after irradiation by thermally stimulating the release of the trapped charges and subjecting them to a temperature gradient. Heating similarly irradiated samples in the absence of a temperature gradient produced a tenfold reduction in the observed current. The charge carriers were determined to be positive from the polarity of the colder electrode. To observe thermoelectric currents, electrons liberated during irradiation had to be trapped to prevent recombination with trapped positive charges. This trapping is not done by the polymer matrix of PMMA at 25°C but by added impurities. PVC contains a built-in trap in the polymer chain at the C-C1 group. The electron trap in commercial PMMA (Lucite) is benzoyl peroxide or another chemical initiator. Electron traps were also internally generated in pure PMMA polymer by radiation followed by heating to 120°C.

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