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Some aspects of polyethylene photooxidation
Author(s) -
Gugumus François
Publication year - 1989
Publication title -
makromolekulare chemie. macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 0258-0322
DOI - 10.1002/masy.19890270104
Subject(s) - photochemistry , chemistry , polyethylene , decomposition , quenching (fluorescence) , intramolecular force , hydrogen peroxide , oxygen , photodissociation , peroxide , radical , amine gas treating , charge transfer complex , homolysis , low density polyethylene , reaction mechanism , organic chemistry , catalysis , fluorescence , physics , quantum mechanics
The hydroperoxides produced by thermal oxidation of LDPE films were used to study their photolysis. Product analysis, kinetics of hydroperoxide decomposition and product formation as well as experiments with model compounds point to new mechanisms of hydroperoxide photolysis. Intermolecular as well as intramolecular decomposition mechanisms are proposed. In polyethylene, these reactions are essentially non‐initiating. In addition, it is confirmed that ketones such as those formed by oxidation of polyethylene do not have a significant initiating effect. Reactions of excited charge‐transfer complexes polyethylene‐oxygen are proposed to account for initiation of photo‐oxidation. One of these reactions yields trans‐vinylene groups and hydrogen peroxide whose direct decomposition or subsequent photolysis will generate hydroxyl radicals. It is found that this reaction is quenched very efficiently by small amounts of HALS (Hindered Amine Light Stabilizers) and by amines in general. It is postulated that quenching is due to energy transfer from the charge‐tranfer complex polymer‐oxygen to a charge‐transfer complex HALS‐oxygen or amine‐oxygen. The data available so far support such a mechanism.