The Experts below are selected from a list of 16791 Experts worldwide ranked by ideXlab platform
Olivier Lame - One of the best experts on this subject based on the ideXlab platform.
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1d strain rate dependent constitutive model of uhmwpe from Crystalline Network to fibrillar structure behavior
Mechanics of Materials, 2019Co-Authors: Tiana Deplancke, Marc Fivel, Olivier LameAbstract:Abstract A combined experimental and analytical investigation has been performed to understand and predict the mechanical behavior of UHMWPE with different molecular weights: 0.6; 3.9 and 10.5 Mg.mol−1. These materials were tested to a wide range of strain rates using uniaxial compression tests on a servo-hydraulic testing machine (10−4 to 10 s−1). A hyperelastic-viscoplastic approach based on a relevant physical basis was adopted to predict the mechanical behavior of UHMWPE. The key point of the proposed model is to capture the huge microstructural evolution which occurs during fibrillation (Crystalline Network collapse) through a mechanical coupling parameter between the confined amorphous phase and the crystal stacks. The description of the amorphous phase is split in two parts, confined and global macromolecular Networks in order to account for experimental results such as the huge strain recovery observed even after large plastic deformation of UHMWPE. It is found that this model successfully describes the compressive hyperelastic-viscoplastic behavior of sintered UHMWPE for different molecular weights over a wide range of strain rates and can be qualitatively extended to high strain rate and tensile loading.
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micro macro stress relationship and local stress distribution in polyethylene spherulites upon uniaxial stretching in the small strain domain
Polymer, 2018Co-Authors: Bijin Xiong, Olivier Lame, Roland SeguelaAbstract:Abstract Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the Crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of Crystalline Network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-Crystalline polymers via micromechanical approaches.
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Micro/macro-stress relationship and local stress distribution in polyethylene spherulites upon uniaxial stretching in the small strain domain
Polymer, 2018Co-Authors: Bijin Xiong, Olivier Lame, Roland Seguela, Yongfeng MenAbstract:Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the Crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of Crystalline Network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-Crystalline polymers via micromechanical approaches. (C) 2018 Elsevier Ltd. All rights reserved.
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Micro/macro-stress relationship and local stress distribution in polyethylene spherulites upon uniaxial stretching in the small strain domain
Polymer, 2018Co-Authors: Bijin Xiong, Olivier Lame, Roland Seguela, Yongfeng MenAbstract:Abstract Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the Crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of Crystalline Network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-Crystalline polymers via micromechanical approaches.
Bijin Xiong - One of the best experts on this subject based on the ideXlab platform.
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micro macro stress relationship and local stress distribution in polyethylene spherulites upon uniaxial stretching in the small strain domain
Polymer, 2018Co-Authors: Bijin Xiong, Olivier Lame, Roland SeguelaAbstract:Abstract Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the Crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of Crystalline Network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-Crystalline polymers via micromechanical approaches.
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Micro/macro-stress relationship and local stress distribution in polyethylene spherulites upon uniaxial stretching in the small strain domain
Polymer, 2018Co-Authors: Bijin Xiong, Olivier Lame, Roland Seguela, Yongfeng MenAbstract:Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the Crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of Crystalline Network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-Crystalline polymers via micromechanical approaches. (C) 2018 Elsevier Ltd. All rights reserved.
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Micro/macro-stress relationship and local stress distribution in polyethylene spherulites upon uniaxial stretching in the small strain domain
Polymer, 2018Co-Authors: Bijin Xiong, Olivier Lame, Roland Seguela, Yongfeng MenAbstract:Abstract Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the Crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of Crystalline Network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-Crystalline polymers via micromechanical approaches.
Yongfeng Men - One of the best experts on this subject based on the ideXlab platform.
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Micro/macro-stress relationship and local stress distribution in polyethylene spherulites upon uniaxial stretching in the small strain domain
Polymer, 2018Co-Authors: Bijin Xiong, Olivier Lame, Roland Seguela, Yongfeng MenAbstract:Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the Crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of Crystalline Network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-Crystalline polymers via micromechanical approaches. (C) 2018 Elsevier Ltd. All rights reserved.
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Micro/macro-stress relationship and local stress distribution in polyethylene spherulites upon uniaxial stretching in the small strain domain
Polymer, 2018Co-Authors: Bijin Xiong, Olivier Lame, Roland Seguela, Yongfeng MenAbstract:Abstract Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the Crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of Crystalline Network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-Crystalline polymers via micromechanical approaches.
Roland Seguela - One of the best experts on this subject based on the ideXlab platform.
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micro macro stress relationship and local stress distribution in polyethylene spherulites upon uniaxial stretching in the small strain domain
Polymer, 2018Co-Authors: Bijin Xiong, Olivier Lame, Roland SeguelaAbstract:Abstract Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the Crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of Crystalline Network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-Crystalline polymers via micromechanical approaches.
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Micro/macro-stress relationship and local stress distribution in polyethylene spherulites upon uniaxial stretching in the small strain domain
Polymer, 2018Co-Authors: Bijin Xiong, Olivier Lame, Roland Seguela, Yongfeng MenAbstract:Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the Crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of Crystalline Network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-Crystalline polymers via micromechanical approaches. (C) 2018 Elsevier Ltd. All rights reserved.
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Micro/macro-stress relationship and local stress distribution in polyethylene spherulites upon uniaxial stretching in the small strain domain
Polymer, 2018Co-Authors: Bijin Xiong, Olivier Lame, Roland Seguela, Yongfeng MenAbstract:Abstract Local stress of polyethylene spherulites under uniaxial stretching in small strain domain has been investigated by in-situ wide angle X-ray diffraction (WAXD) in comparison with macroscopic stress. Particular attention is paid to the elastic strain range. The local stress in equatorial and polar regions both increase in absolute value and follow a linear relation versus macroscopic stress. However, local stress turns out to be heterogeneous over the whole spherulites volume. The polar region shows higher local stress than equatorial region. Moreover, local stress along the a and b crystallographic axes in the Crystalline lamellae enable determining the local stress triaxiality which is heterogenous. The increase of crystallinity promotes stress distribution heterogeneity throughout the spherulites. The origin of these phenomenon are discussed in terms of Crystalline Network percolation and effect of amorphous layer that modifies the local mechanical behavior. The present study provides a useful means for achieving the scale transition between the micro and the macro structural levels that is necessary for the modeling of the mechanical behavior of semi-Crystalline polymers via micromechanical approaches.
Nicolas Keller - One of the best experts on this subject based on the ideXlab platform.
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Synergy effect between photocatalysis and heterogeneous photo-Fenton catalysis on Ti-doped LaFeO 3 perovskite for high efficiency light-assisted water treatment
Catalysis Science & Technology, 2020Co-Authors: Patricia Garcia-muñoz, Fernando Fresno, Christophe Lefèvre, Didier Robert, Nicolas KellerAbstract:A strategy combining both heterogenized photo-Fenton and photocatalysis advanced oxidation processes in a single dual catalyst is developed for simultaneously benefiting from the higher reaction rate of photo-Fenton and the higher mineralization yield of photocatalysis in water treatment, while overcoming the strong drawbacks still limiting their viability as single processes. We prepared via a facile Pechini sol-gel route a highly efficient and stable Ti-substituted LaFeO3 dual catalyst, active simultaneously as reusable photo-Fenton solid catalyst and photocatalyst in water treatment. The partial substitution of La by Ti ions in the Crystalline Network led to pure heterogeneous surface reactions with an increase in the catalyst robustness by more than two orders of magnitude, symbolized by the absence of any Fe release and the stability of catalytic performance with test cycles. It further strongly enhanced the reaction rates, due to both an increased availability of the photogenerated charge carriers at the surface and the electronic enrichment of surface Fe, and allowed full mineralization of the pollutant to be achieved at circumneutral pH through combined advanced oxidation processes.
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synergy effect between photocatalysis and heterogeneous photo fenton catalysis on ti doped lafeo3 perovskite for high efficiency light assisted water treatment
Catalysis Science & Technology, 2020Co-Authors: Patricia Garciamunoz, Fernando Fresno, Christophe Lefèvre, Didier Robert, Nicolas KellerAbstract:A strategy combining both heterogenized photo-Fenton and photocatalysis advanced oxidation processes for a single dual catalyst is developed simultaneously benefiting from the higher reaction rate of photo-Fenton and the higher mineralization yield of photocatalysis in water treatment, while overcoming the strong drawbacks still limiting their viability as single processes. We prepared via a facile Pechini sol–gel route a highly efficient and stable Ti-substituted LaFeO3 dual catalyst, acting simultaneously as a reusable photo-Fenton solid catalyst and a photocatalyst in water treatment. The partial substitution of La by Ti ions in the Crystalline Network led to pure heterogeneous surface reactions with an increase in the catalyst robustness by more than two orders of magnitude, indicating the absence of any Fe released and the stability of catalytic performance with test cycles. It further strongly enhanced the reaction rates, due to both increased availability of the photogenerated charge carriers at the surface and the electronic enrichment of surface Fe, and allowed full mineralization of a pollutant to be achieved at circumneutral pH through combined advanced oxidation processes.