Oxidation of unvulcanized, unstabilized polychloroprene: a kinetic study

Type Article
Date 2014-11
Language English
Author(s) Le Gac Pierre YvesORCID1, Roux Gerard2, Verdu Jacques3, Davies PeterORCID1, Fayolle Bruno3
Affiliation(s) 1 : IFREMER, Ctr Bretagne, Marine Struct Lab, F-29280 Plouzane, France.
2 : Thales Underwater Syst, F-06903 Sophia Antipolis, France.
3 : Arts & Metiers ParisTech, PIMM, F-75013 Paris, France.
Source Polymer Degradation And Stability (0141-3910) (Elsevier Sci Ltd), 2014-11 , Vol. 109 , P. 175-183
DOI 10.1016/j.polymdegradstab.2014.06.019
WOS© Times Cited 12
Keyword(s) Polychloroprene, Oxidation, Radical chain, Kinetics
Abstract Thermal oxidation in air at atmospheric pressure, in the 80-140°C temperature range and in oxygen at 100°C in the 0.02-3 MPa pressure range, of unvulcanized, unstabilized, unfilled polychloroprene (CR) has been characterized using FTIR and chlorine concentration measurement. The kinetic analysis was focused on double bond consumption. A mechanistic scheme involving unimolecular and bimolecular hydroperoxide decomposition, oxygen addition to alkyl radicals, hydrogen abstraction on allylic methylenes, alkyl and peroxyl additions to double bonds and terminations involving alkyl and peroxy radicals was elaborated. The corresponding rate constants were partly extracted from the literature and partly determined from experimental data using the kinetic model derived from the mechanistic scheme in an inverse approach. Among the specificities of polychloroprene, the following were revealed: The rate of double bond consumption is a hyperbolic function of oxygen pressure that allows a law previously established for the oxidation of saturated substrates to be generalized. CR oxidation is characterized by the absence of an induction period that reveals the instability of hydroperoxides. The kinetic analysis also reveals that peroxyl addition is faster than hydrogen abstraction but slower in CR than in common hydrocarbon polydienes.
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