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Photosensitized degradation of polyolefins
Author(s) -
Cernia E.,
Mantovani E.,
Marconi W.,
Mazzei M.,
Palladino N.,
Zanobi A.
Publication year - 1975
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.1975.070190102
Subject(s) - photodegradation , polyethylene , degradation (telecommunications) , photochemistry , benzophenone , polymer , polymer degradation , singlet oxygen , chemistry , oxygen , materials science , hydrogen atom abstraction , excited state , reaction mechanism , polymer chemistry , organic chemistry , hydrogen , catalysis , photocatalysis , telecommunications , physics , computer science , nuclear physics
The effect of aromatically substituted dienes such as 1,1,4,4‐tetraphenylbutadiene (TPB) as sensitizers of the accelerated oxidative photodegradation of polyethylene has been studied. The mechanism of photosensitization has been investigated by ESR and IR spectroscopy, while the degradation rate has been monitored by following the change of the mechanical properties during accelerated indoor and outdoor weathering tests. It was found that TPB is an efficient sensitizer for the oxidative degradation of polyethylene. The degradation of the polymer takes place via 1 O 2 formation, and it was interpreted on the basis of two simultaneous processes. In the first, excited singlet oxygen ( 1 O 2 ) is produced by TPB itself or by ketonic impurities present in the polymer. In the second, 1 O 2 reacts with TPB giving benzophenone, peroxides, and other oxygenated products which in turn can promote the degradation of polyethylene. Irradiation carried out in the absence of air seems to rule out the possibility of a photodegradation mechanism via excitation of TPB to an upper excited state capable of hydrogen abstraction from the polymer.