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Water diffusivity in PA66: Experimental characterization and modeling based on free volume theory ArchiMer
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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Moisture sorption in polyamide 6.6: experimental investigation and comparison to four physical-based models ArchiMer
Broudin, Morgane; Le Saux, V.; Le Gac, Pierre-yves; Champy, C.; Robert, G.; Charrier, P.; Marco, Y..
Water sorption in polyamide 6.6 has been characterized for a wide range of temperature (25°C to 80°C) and various water activities using a Dynamic Vapor Sorption testing machine. Complex sorption mechanisms govern the water uptake in the material. The competition between two main temperature dependant mechanisms has been observed: a Henry’s sorption mechanism that mainly governs the sorption curve at low water activities, and a second mechanism at high water activities that could be related to the formation of water clusters. It is observed that the temperature dependency can mainly be attributed to the Henry’s contribution. Four physically based models are then used and identified thanks to the extended experimental database. It is shown that a simple...
Tipo: Text Palavras-chave: Polyamide 6.6; Water sorption; Temperature; Relative humidity; Physically-based models.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00252/36371/34911.pdf
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Ageing mechanism and mechanical degradation behaviour of polychloroprene rubber in a marine environment: Comparison of accelerated ageing and long term exposure ArchiMer
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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Limits in the validity of Arrhenius predictions for field ageing of a silica filled polychloroprene in a marine environment ArchiMer
Le Saux, V.; Le Gac, Pierre-yves; Marco, Y.; Calloch, S..
Accelerated ageing in natural sea water at different temperatures from 20°C to 80°C was performed on a silica filled polychloroprene rubber. Degradation when monitored with mechanical properties at both macroscopic and microscopic scale led to a large increase of the modulus coupled with a strong decrease of strain and stress at break. Data from tensile tests were used for lifetime prediction with an Arrhenius extrapolation for modulus, strain and stress at break. The validity of this lifetime prediction was evaluated using a 23 year-old sample aged in natural conditions. Strain at break could be predicted using an Arrhenius extrapolation with an activation energy of 50 kJ/mol. However, an extrapolation based on linear Arrhenius behavior did not apply for...
Tipo: Text Palavras-chave: Polychloroprene rubber; Accelerated and natural ageing tests; Arrhenius extrapolation; Lifetime prediction; Sea water.
Ano: 2014 URL: http://archimer.ifremer.fr/doc/00164/27523/25679.pdf
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