AbstractThe effect of N‐methyl dithiocarbamate substitution on the radiation stability of poly‐(vinyl chloride) (PVC) films was studied. PVC containing between 2 and 11 mole‐ N‐methyl dithiocarbamate (PMD) was irradiated with γ‐rays from a60Co source at 40°C and the evolved gaseous products were measured and analyzed with a mass spectrometer. The apparentGvalues for gas evolution for PMD decreased remarkably. For example, aGvalue of 0.28 was obtained for a PMD which contains 11 mole‐ dithiocarbamate group compared with aGvalue of 10.8 for unmodified poly(vinyl chloride). Furthermore, the mass spectrum of the evolved gas from the same PMD sample (PMD‐44) with 10 Mrad irradiation showed no hydrogen chloride to be present. The external protection was studied using polymer‐blended films of PVC and PMD‐44. The stabilization coefficients for internal protection and external protection in polymer blends were calculated. The ESR spectrum of the irradiated PMD‐44 showed a strong anisotropy with highgvalues which differed significantly from the spectrum of the irradiated PVC. A suggested mechanism for radiation protection of PVC against γ‐rays irradiation by the N‐methyl dithioca
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