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Thermooxidative ageing of polyoxymethylene, part 1: Chemical aspects
Author(s) -
Fayolle B.,
Verdu J.,
Bastard M.,
Piccoz D.
Publication year - 2007
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.26648
Subject(s) - depolymerization , formate , polyoxymethylene , decomposition , thermal decomposition , kinetic energy , oxygen , chemistry , mass spectrometry , activation energy , polymer chemistry , materials science , organic chemistry , polymer , catalysis , physics , chromatography , quantum mechanics
The thermal oxidation of unstabilised POM homopolymer has been studied at 90, 110, and 130°C under various oxygen pressures ranging from 0 to 2.0 MPa by gravimetry and IR spectrometry. This latter reveals essentially the formation of formate (F) groups and alcohols in smaller quantities. The formate growth and mass loss rates increase pseudo hyperbolically with oxygen pressure, the asymptotic level being reached at pressures up to 0.5 MPa. These results lead to propose a mechanistic scheme of radical chain oxidation in which depolymerization is initiated by hydroperoxide unimolecular decomposition, one formate and one chain scission being formed per decomposition event whereas the kinetic chain length of the depolymerization zip is of the order of 100. A kinetic model derived from the mechanistic scheme, taking into account substrate consumption, simulates correctly the shape of kinetic curves and the effect of temperature and oxygen pressure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008