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Electron spin resonance studies on graft copolymerization of gaseous styrene onto preirradiated polypropylene. III. Preirradiation under vacuum followed by exposure to oxygen at −78°C
Author(s) -
Nunome Keichi,
Eda Bunzo,
Iwasaki Machio
Publication year - 1974
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1974.070180914
Subject(s) - radical , polypropylene , oxygen , photochemistry , hydrogen atom abstraction , electron paramagnetic resonance , styrene , chemistry , irradiation , copolymer , hydrogen , polymer chemistry , materials science , organic chemistry , polymer , nuclear magnetic resonance , physics , nuclear physics
Grafting of styrene vapor was carried out onto polypropylene γ‐irradiated under vacuum followed by exposure to oxygen at −78°C. A comparison with the results on polypropylene irradiated in an oxygen atmosphere leads to an interesting result. Two samples were irradiated at room temperature under vacuum and in an oxygen atmosphere, respectively, the former being followed by exposure to oxygen. Although irradiation was carried out at room temperature for either sample and nearly the same amounts of the peroxy radicals are trapped, the former showed more grafting than the latter. The origin of this difference was investigated by means of electron spin resonance. Significant differences were observed in ESR spectra as well as in isothermal decays of the trapped peroxy radicals. In the former sample, the trapped peroxy radicals had a higher mobility, and consequently a significant hydrogen abstraction by the peroxy radicals was observed during storage at 40°C. This result supports the conclusion of the previous paper that the radicals effective in the grafting reaction of polypropylene preirradiated in an oxygen atmosphere are the carbon radicals which are produced by hydrogen abstraction by the peroxy radicals.