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| Le Gac, Pierre Yves; Roux, Gerard; Verdu, Jacques; Davies, Peter; Fayolle, Bruno. |
| 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... |
| Tipo: Text |
Palavras-chave: Polychloroprene; Oxidation; Radical chain; Kinetics. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00199/31010/29413.pdf |
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| Tchalla, Siwavi Tatiana; Le Gac, Pierre-yves; Maurin, R.; Creac'Hcadec, R.. |
| Polychloroprene rubbers are widely used in marine structures and often filled with silica in order to increase mechanical properties. The presence of silica fillers leads to a complex degradation of the material. This study aims to understand the deeper degradation mechanisms involved when a silica filled polychloroprene is used in sea water. To do so, 4 polychloroprene rubbers filled with different amounts of silica (from 0 to 45 phr) were aged in natural sea water for 6 months at temperatures ranging from 25 to 60 °C. Moreover, a natural rubber with similar formulation was also considered in order to evaluate the role of the chlorine atom in the degradation. . The chemistry and mechanics of the rubber degradation were also studied. In the presence of... |
| Tipo: Text |
Palavras-chave: Polychloroprene; Seawater; Silica filler; Hydrolysis. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00376/48689/49020.pdf |
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| Le Gac, Pierre Yves; Albouy, Pierre-antoine; Sotta, Paul. |
| It is shown in the present paper how the addition of a moderate amount of carbon black filler to a polychloroprene gum modifies the local strain state and alters the ability of the polymer to strain-crystallize. The study combines mechanical and X-ray diffraction performed during classical mechanical cycling and tensile impact tests. It highlights the fact that the strain modification induced by the filler addition is highly inhomogeneous: the crystallization behavior and the local draw ratio state are affected differently. The partial relaxation of the amorphous fraction by the strain-induced crystallization peviously evidenced in the pure gum is still present and should play a protective role. The effect of temperature on the crystallization correlates... |
| Tipo: Text |
Palavras-chave: Polychloroprene; Strain-induced crystallization; X-ray. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00488/60003/63239.pdf |
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| Le Gac, Pierre-yves; Albouy, Pierre-antoine; Petermann, Denis. |
| Polychloroprene rubber is often quoted as an example of strain-crystallizing elastomer; however, this fundamental property, known to impart good mechanical properties and fatigue resistance, has received much less attention in this class of compounds than natural rubber. The present paper relates systematic investigations combining mechanical and X-ray diffraction measurements. Crystallization kinetics are first investigated based on tensile impact tests. An approximately logarithmic time-dependence is found for the crystalline content and the time-constants are estimated at various temperatures. The impact of strain-induced crystallization on stress-strain curves under mechanical cycling conditions is further assessed. It is demonstrated that one main... |
| Tipo: Text |
Palavras-chave: Polychloroprene; Strain-induced crystallization; X-ray. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00433/54467/55842.pdf |
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| Le Gac, Pierre-yves; Roux, Gerard; Davies, Peter; Fayolle, Bruno; Verdu, Jacques. |
| 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 1.9 and 3.8 mm thickness (Constant Temperature and Hygrometry, CTH experiments), then at fixed temperature (40°C) and several hygrometric ratios ranging from 0 to 95% HR on samples of 0.1 mm thickness (DVS experiments). CTH experiments reveal an abnormal sorption behavior: after an apparently fickian transient period, the water absorption continues at almost constant rate, no equilibrium is observed after more than 2500 hours, whatever the temperature. DVS experiments reveal a very low Henry’s solubility but the formation of clusters at water activities higher than 40%.... |
| Tipo: Text |
Palavras-chave: Polychloroprene; Water sorption; Clustering. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00188/29903/28350.pdf |
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