Oxidation of unvulcanized, unstabilized polychloroprene: A kinetic study
Article dans une revue avec comité de lecture
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.
Showing items related by title, author, creator and subject.
Role of strain induced crystallization and oxidative crosslinking in fracture properties of rubbers Article dans une revue avec comité de lectureLE GAC, Pierre Yves; BROUDIN, Morgane; ROUX, Gérard; VERDU, Jacques; DAVIES, Peter; FAYOLLE, Bruno (Elsevier, 2014)Tensile properties and crack propagation properties, especially critical strain energy release rate in mode I, GIC, have been used to investigate fracture properties of elastomers and their relationships with microstructure. ...
Article dans une revue avec comité de lectureLE GAC, Pierre Yves; ROUX, Gérard; DAVIES, Peter; FAYOLLE, Bruno; VERDU, Jacques (Elsevier, 2014)Water sorption has been studied gravimetrically for polychloroprene rubber samples, first at a fixed hygrometric ratio (98% HR) and several temperatures (25, 40, 60 and 80 °C) for samples of 1.8 and 3.8 mm thickness (Constant ...
Article dans une revue avec comité de lectureLE GAC, Pierre Yves; CELINA, Mathew C.; ROUX, Gérard; VERDU, Jacques; DAVIES, Peter; FAYOLLE, Bruno (Elsevier, 2016)The oxidative ageing in the range of 60 °C–140 °C of sulfur vulcanized polychloroprene has been studied by FTIR spectroscopy (double bond consumption), modulus changes and oxygen absorption measurements. Experiments were ...
Relationship between macromolecular network and fatigue properties of unfilled polychloroprene rubber Article dans une revue avec comité de lectureLE GAC, Pierre-Yves; ALBOUY, Pierre-Antoine; FAYOLLE, Bruno; VERDU, Jacques (Elsevier, 2021)Fatigue life of unfilled polychloroprene rubber is characterized in fully relaxing (R = 0) and non-relaxing conditions (R = 0.2) for more than 15 network structures. Network changes are induced by thermal oxidation ageing ...
Article dans une revue avec comité de lectureRICHAUD, Emmanuel; LE GAC, Pierre Yves; VERDU, Jacques; LE GAC, Pierre Yves (Elsevier, 2014)Thermal aging of thin ﬁlms of unstabilized polydicyclopentadiene (pDCPD) at several temperatures ranging from 120 to 30 C was investigated by means of carbonyl build up by FTIR with ammonia derivatization, double bond ...