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| Registros recuperados: 30 | |
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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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| Broudin, M.; Le Gac, Pierre-yves; Le Saux, V.; Champy, C.; Robert, G.; Charrier, P.; Marco, Y.. |
| Diffusion of water in polyamide 6.6 has been characterized for a wide range of temperatures (from 25 to 80 °C) and various humidities using dynamic vapor sorption machine. The decrease in glass transition temperature (Tg) has also been measured using DMA tests. As usually observed, PA66 absorbs a large amount of water (up to 5% at 90%RH) with a Fickian behavior with a diffusion coefficient that depends on water activity for all temperatures. Moreover, it appears that the diffusion coefficient for tests performed below Tg is almost independent of the water activity whereas a strong dependency is observed above Tg. This behavior is to be compared to a large decrease of Tg with the absorption of water. The increase of the water diffusion can therefore be... |
| Tipo: Text |
Palavras-chave: Water absorption; Free volume; Polyamide; Modeling. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00260/37148/35794.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; 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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| 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; Choqueuse, Dominique; Paris, Marc; Recher, G.; Zimmer, Celine; Melot, D.. |
| In the offshore industry polymer coatings are widely used to ensure thermal insulation of steel pipes, and to avoid over-cooling of the hot oil inside. Because of very severe service conditions (i.e. high temperature, high pressure and presence of seawater) and an expected life time of 20 years, durability of these coatings is a major issue for this industry. Polypropylene and polyurethane are often used for this application, nevertheless these polymers have some limitations in terms of processing time for polypropylene and maximum service temperature for polyurethane. Polycyclopentadiene (pDCPD) shows good processing characteristics and low thermal conductivity, so this polymer could be a good alternative coating in the offshore industry, but the... |
| Tipo: Text |
Palavras-chave: Polydicyclopentadiene; Seawater; Accelerated ageing; Oxidation; Offshore; Field joint. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00114/22534/20233.pdf |
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| Le Guen-geffroy, Antoine; Le Gac, Pierre-yves; Diakhate, Malick; Habert, Bertrand; Davies, Peter. |
| Composite propellers are a major new development in the marine transport industry. The use of composite materials in seawater turbines is also of great interest to the marine renewable energy industry. Those systems present similarities being both constantly immersed in seawater, under fatigue loadings, of large dimensions, and they are often designed using Carbon Fibre Reinforced Polymer (CFRP). Previous studies have shown sensitivity of some composite materials to the seawater environment mainly in the quasi-static loading domain. However, investigations now need to be performed on the behaviour of CFRP under seawater environment and fatigue loadings. In this study, CFRP samples were aged in natural seawater until saturation, in order to investigate the... |
| Tipo: Text |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00441/55262/56756.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; 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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| 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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| 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. |
| Accelerated ageing was performed in distilled water at different temperatures (25, 30, 40 and 50°C) on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), which is a biodegradable biopolymer, in order to estimate its lifetime in aqueous environment. In a first part, degradation mechanisms were followed by gravimetry, tensile tests and steric exclusion chromatography. Both immersion and relative humidity have been examined. In a second part, the strain at break was used as an indicator for lifetime prediction with an Arrhenius extrapolation. The study revealed the presence of only one irreversible degradation mechanism, i.e. hydrolytic degradation, which is temperature dependant. So, within the approach assumptions, the lifetime in distilled water of PHBV... |
| Tipo: Text |
Palavras-chave: Poly(3-hydroxybutyrate-co-3-hydroxyvalerate); Accelerated ageing; Hydrothermal degradation; Lifetime prediction. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00203/31396/29785.pdf |
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| Le Gall, Maelenn; Choqueuse, Dominique; Le Gac, Pierre-yves; Davies, Peter; Perreux, Dominique. |
| Syntactic foams, used in submersibles and in pipelines for deep sea oil wells, must be resistant to the severe conditions of the deep sea environment. As these foams will be in service for at least 20 years, their qualification testing is crucial. However, their mechanical characterization under real conditions of use is a challenge. In deep sea, the main loading is hydrostatic compression, however there is no standard procedure for testing material under pure hydrostatic pressure. The aim of this paper is to present a new characterization technique based on buoyancy loss measurement under hydrostatic pressure. To validate the method, two different syntactic foams (one brittle and one ductile) have been tested. Their behaviours under hydrostatic pressure... |
| Tipo: Text |
Palavras-chave: Hydrostatic compression; Syntactic foam; Deep sea; Mechanical characterization. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00201/31191/29590.pdf |
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| Deroine, Morgan; Le Duigou, Antoine; Corre, Yves-marie; Le Gac, Pierre-yves; Davies, Peter; Cesar, Guy; Bruzaud, Stephane. |
| Pollution of nature by plastics is a major environmental problem and the challenge for the future is to manage the lifetime of polymers better. The aim of this study is to establish a baseline on degradation mechanism and degradation kinetics for lifetime prediction of polylactide (PLA) in a marine environment. The ageing of PLA was accelerated by raising temperature in distilled water, filtered and renewed seawater and natural seawater. Samples were immersed in distilled water for six months at different temperatures (25, 30, 40 and 50°C) in order to evaluate the influence of temperature on PLA degradation kinetics and to predict lifetime. Then, samples were immersed in seawater both in the laboratory and at sea, in order to compare the effects of... |
| Tipo: Text |
Palavras-chave: PLA; Accelerated ageing; Hydrothermal ageing; Degradation. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00173/28376/26689.pdf |
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| Registros recuperados: 30 | |
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