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| Registros recuperados: 30 | |
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| Le Gac, Pierre-yves; Davies, Peter; Choqueuse, Dominique. |
| Polymers and composites are very attractive for underwater applications, but it is essential to evaluate their long term behaviour in sea water if structural integrity of offshore structures is to be guaranteed. Accelerated test procedures are frequently required, and this paper will present three examples showing how the durability of polymers, in the form of fibres, matrix resins in fibre reinforced composites for structural elements, and thermal insulation coatings of flow-lines, have been evaluated for offshore use. The influence of the ageing medium, temperature, and hydrostatic pressure will be discussed first, then an example of the application of ageing test results to predict long term behavior of the thermal insulation coating of a flowline will... |
| Tipo: Text |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00199/30978/29356.pdf |
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| Le Gac, Pierre-yves; Arhant, Mael; Le Gall, Maelenn; Davies, Peter. |
| This paper considers the effect of water content on mechanical properties of polyamide 6 when used in a humid environment. First an experimental section presents the tensile behavior of polyamide with different amounts of water, with and without a through-thickness water gradient. Water profiles are introduced by immersion in sea water at 25 °C. The effect of testing temperature is also investigated in order to consider the influence of macromolecular chain mobility on the mechanical behavior. Then, in a second section, modelling of yield stress is proposed based on physical considerations. This can be used for life time prediction of PA6 in humid environment when plasticization is the main degradation mechanism. |
| Tipo: Text |
Palavras-chave: Yield stress; Water; Polyamide; Plasticization; Prediction. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00371/48208/48321.pdf |
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| Le Gac, Pierre-yves; Arhant, Mael; Davies, Peter; Muhr, Alan. |
| Natural rubber has been successfully used in a marine environment for many years. However, most applications involve low dynamic loadings. Due to the emergence of marine energy recovery, wave and tidal energy converters are being developed. In some such devices, rubbers are subjected to severe cyclic loadings, very different from their previous use in air or water. Such rubbers must therefore be qualified for long-term use in sea water with high fatigue loading. This paper presents a study using a new fatigue machine that allows the fatigue behaviour of rubber in sea water to be compared to that in air. The results show that the benefit of non-relaxing conditions on fatigue lifetime of natural rubber can be significantly reduced when it is used in sea... |
| Tipo: Text |
Palavras-chave: Natural Rubber; Water; Fatigue; Stabilisation. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00211/32240/32195.pdf |
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| Richaud, Emmanuel; Le Gac, Pierre-yves; Verdu, Jacques. |
| Thermal ageing 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 titration, mass uptake measurement, hydroperoxides titration by iodometry and DSC coupled with sulfur dioxide treatment. In the temperature range under investigation, pDCPD is in glassy state and it oxidizes faster than common polymers oxidized at rubbery state (e.g. polydienic elastomers). Using the kinetic analysis, these results were ascribed to increased initiation rate due to catalyst residues, some possible intramolecular processes favoring propagation, or a very low termination rate of oxidation radical chains because of the control... |
| Tipo: Text |
Palavras-chave: Polydicyclopentadiene; Thermal oxidation; Kinetics; Molecular mobility. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00175/28646/27073.pdf |
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| Deroine, Morgan; Le Duigou, Antoine; Corre, Yves-marie; Le Gac, Pierre-yves; Davies, Peter; Cesar, Guy; Bruzaud, Stephane. |
| The aim of this study is to establish a baseline for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) lifetime prediction in a marine environment, by means of mechanical and physico-chemical characterization of specimens immersed in continuously renewed and filtered natural seawater in the laboratory at different temperatures (4, 25 and 40°C). Samples were also aged at sea in Lorient harbour in order to compare laboratory and natural degradation mechanisms and kinetics. Due to its morphology, hydrolysis of PHBV in natural seawater is quite slow, and samples were observed to undergo preferentially an enzymatic surface degradation. Increasing the aging temperature in the laboratory promotes the water uptake and causes hydrolysis. As two degradation... |
| Tipo: Text |
Palavras-chave: Poly(3-hydroxybutyrate-co-3-hydroxyvalerate); Accelerated ageing; Hydrothermal degradation; Seawater. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00188/29972/28425.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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| Ilioni, Alin; Le Gac, Pierre-yves; Badulescu, Claudiu; Thévenet, David; Davies, Peter. |
| This article describes an approach to predict the behaviour of an epoxy adhesive in bulk form in a marine environment. First, the material, the experimental conditions and the predictive framework are described. Then the experimental results are presented, which indicate that the effects on yield stress of either a uniform water profile or elevated testing temperature can be shown to be equivalent when plotted versus T-Tg. Moreover, a discussion of these results shows how they can be used to predict changes in the mechanical properties of the adhesive. Prediction results for yield stress are in good agreement when they are compared with experimental results for the case of a water profile gradient, in order to evaluate the relevance and limitations of the... |
| Tipo: Text |
Palavras-chave: Epoxide; Water ageing; Glass transition temperature; Mechanical properties of adhesives; Plasticisation. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00419/53052/54052.pdf |
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| Defauchy, Virginie; Le Gac, Pierre-yves; Guinault, Alain; Verdu, Jacques; Recher, Gilles; Drozdzak, Renata; Richaud, Emmanuel. |
| The in situ thermal oxidation of thin unstabilized polydicyclopentadiene was studied by TGA to monitor mass gain, and DSC to characterize hydroperoxides concentration. Results were discussed using kinetic analysis, which allowed the estimation of activation energies for key reactions of the oxidation process. Activation energy for termination was shown to be higher than in hydrocarbon liquids, which was discussed from the theory of diffusion controlled reactions, and a possible link with local motions associated with sub-glassy transition. Activation energy of thermal decomposition of hydroperoxides was found lower than for model hydroperoxides, suggesting an accelerating effect of organometallic catalysts. Despite those two results that indicate a poor... |
| Tipo: Text |
Palavras-chave: Polydicyclopentadiene; Thermal oxidation; Segmental mobility; Catalysis; Diffusion limited oxidation. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00388/49904/50476.pdf |
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| Le Gac, Pierre-yves; Le Saux, V.; Paris, M; Marco, Y.. |
| Polymers are widely used in marine environments due to their excellent properties and good weathering resistance. Despite this extensive use, their long term behaviour in such an aggressive environment is still not well known. To assess the polymer durability within reasonable durations, it is essential to perform accelerated ageing tests to accelerate the degradation kinetics but without any modification of the degradation process. This study therefore proposes and validates accelerated ageing tests to study marine ageing of a silica-filled chloroprene rubber (CR) used for offshore applications. Several accelerated ageing protocols are investigated for temperatures ranging from 20 to 80 degrees C in renewed natural seawater. The ageing consequences are... |
| Tipo: Text |
Palavras-chave: Chloroprene rubber; Degradation; Sea water; Silica; Accelerated ageing; Natural ageing. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00073/18429/20232.pdf |
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| Davies, Peter; Le Gac, Pierre-yves; Le Gall, Maelenn. |
| A new matrix resin was recently introduced for composite materials, based on acrylic resin chemistry allowing standard room temperature infusion techniques to be used to produce recyclable thermoplastic composites. This is a significant advance, particularly for more environmentally-friendly production of large marine structures such as boats. However, for such applications it is essential to demonstrate that composites produced with these resins resist sea water exposure in service. This paper presents results from a wet aging study of unreinforced acrylic and glass and carbon fibre reinforced acrylic composites. It is shown that the acrylic matrix resin is very stable in seawater, showing lower property losses after seawater aging than those of a... |
| Tipo: Text |
Palavras-chave: Acrylic; Thermoplastic; Infusion; Seawater; Immersion. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00347/45815/45541.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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| Le Gac, Pierre-yves; Broudin, Morgane; Roux, Gérard; Verdu, Jacques; Davies, Peter; Fayolle, Bruno. |
| 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. These investigations were mainly based on a series of comparisons: first, the behaviour of polychloroprene rubber (CR), undergoing stress hardening due to strain induced crystallization (SIC) and oxidative crosslinking (OCL) was compared with that of chlorinated polyethylene (CPE), which undergoes SIC but not OCL, and with a polyurethane based on hydroxyl terminated polybutadiene (PU) which undergoes OCL but not SIC. Comparisons were also made on CR between fracture behaviour at ambient temperature, where SIC occurs and at 100°C where... |
| Tipo: Text |
Palavras-chave: Fracture; Rubber; Oxidation. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00184/29546/27872.pdf |
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| Le Gac, Pierre-yves; Choqueuse, Dominique; Melot, D.. |
| Polymers are widely used for passive thermal insulation coatings on steel pipe in offshore oil and gas production. In this industry, structures used in deep sea have to be reliable, as they are in service for more than 20 years in a very severe environment: sea water, hydrostatic pressure and temperature gradient. One of the main questions is how to test and predict the lifetime of such structures in the laboratory? This study presents one approach that has been developed to characterize and predict the degradation of polymers used as thermal insulation materials. This paper is dedicated to polyurethane (polyether based) degradation in sea water at high temperature. Ageing has been performed in natural sea water under hydrostatic pressure at temperatures... |
| Tipo: Text |
Palavras-chave: Polyurethane; Hydrolysis; Accelerated ageing; Sea water; Coating; Offshore. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00160/27132/25330.pdf |
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| Le Gac, Pierre-yves; Choqueuse, Dominique; Melot, D.; Melve, B.; Meniconi, L.. |
| Polymers are widely used for passive thermal insulation coatings on steel pipe in offshore oil and gas production. In this industry, structures used in deep sea have to be reliable as they are in service for more than 20 years in a very severe environment: sea water, hydrostatic pressure, temperature. One of the main questions is how to test and predict the lifetime of such structures in the laboratory. This study presents one approach that has been developed to characterize and predict the degradation of polyurethanes used as thermal insulation materials. Based on results obtained during accelerated ageing of the PU in sea water, a prediction of degradation through the thickness has been set up taking into account the temperature profile in the coating,... |
| Tipo: Text |
Palavras-chave: Polyurethane; Life time prediction; Hydrolysis; Offshore; Thermal insulation; Durability. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00174/28572/26957.pdf |
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| Registros recuperados: 30 | |
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