Greffage du methacrylate de methyle et de l'acrylonitrile sur des films de poly (chlorure de vinyle) preirradies

Grafting of MAM and ANon PVC films which have previously been irradiated under vacuum or in the presence of air have been studied. After irradiation under vacuum the PVC films occlude some entrapped radicals which start the grafting and which do not give rise to any homopolymerization. The rate of grafting attains a limit at an amount of pre-irradiation of about 1 Mrad. Grafting is a maximum when the reaction is carried out at 30–40°. Irradiation in the presence of air leads to some entrapped radicals but also to some peroxides. The reaction continues for a very long time at constant velocity. The velocity of grafting increases at first with the amount of pre-irradiation, but shows a sharp maximum towards 3 Mrads and then decreases. This phenomenon is attributed to induced decomposition of the peroxides formed. The results as a whole suggest that irradiation of PVC in the presence of air leads to a peroxidation in a short chain with the formation of hydroperoxides.