The Experts below are selected from a list of 402 Experts worldwide ranked by ideXlab platform
H Abiri - One of the best experts on this subject based on the ideXlab platform.
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eddy current and total power loss separation in the iron phosphate Polyepoxy soft magnetic composites
Materials & Design, 2009Co-Authors: Amir Hossei Taghvaei, H Shokrollahi, K Janghorba, H AbiriAbstract:Abstract This work investigates the magnetic properties of iron–phosphate–Polyepoxy soft magnetic composite materials. FTIR spectra, EDX analysis, distribution maps, X-ray diffraction pattern and density measurements show that the particles surface layer contains a thin layer of nanocrystalline/amorphous phosphate with high coverage of powders surface. In this paper, a formula for calculating the eddy current loss and total loss components by loss separation method is presented and finally the different parts of power losses are calculated. The results show that, the contribution of eddy current in the bulk material for single coating layer (kb = 0.18) is higher in comparison with double coating layer (kb = 0.09). Moreover, iron–phosphate–Polyepoxy composites (P = 0.000004f2) have lower power loss in comparison with iron–phosphate composites (P = 0.00002f2).
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Eddy current and total power loss separation in the iron–phosphate–Polyepoxy soft magnetic composites
Materials & Design, 2009Co-Authors: Amir Hossei Taghvaei, H Shokrollahi, Kamal Janghorban, H AbiriAbstract:Abstract This work investigates the magnetic properties of iron–phosphate–Polyepoxy soft magnetic composite materials. FTIR spectra, EDX analysis, distribution maps, X-ray diffraction pattern and density measurements show that the particles surface layer contains a thin layer of nanocrystalline/amorphous phosphate with high coverage of powders surface. In this paper, a formula for calculating the eddy current loss and total loss components by loss separation method is presented and finally the different parts of power losses are calculated. The results show that, the contribution of eddy current in the bulk material for single coating layer (kb = 0.18) is higher in comparison with double coating layer (kb = 0.09). Moreover, iron–phosphate–Polyepoxy composites (P = 0.000004f2) have lower power loss in comparison with iron–phosphate composites (P = 0.00002f2).
Amir Hossei Taghvaei - One of the best experts on this subject based on the ideXlab platform.
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eddy current and total power loss separation in the iron phosphate Polyepoxy soft magnetic composites
Materials & Design, 2009Co-Authors: Amir Hossei Taghvaei, H Shokrollahi, K Janghorba, H AbiriAbstract:Abstract This work investigates the magnetic properties of iron–phosphate–Polyepoxy soft magnetic composite materials. FTIR spectra, EDX analysis, distribution maps, X-ray diffraction pattern and density measurements show that the particles surface layer contains a thin layer of nanocrystalline/amorphous phosphate with high coverage of powders surface. In this paper, a formula for calculating the eddy current loss and total loss components by loss separation method is presented and finally the different parts of power losses are calculated. The results show that, the contribution of eddy current in the bulk material for single coating layer (kb = 0.18) is higher in comparison with double coating layer (kb = 0.09). Moreover, iron–phosphate–Polyepoxy composites (P = 0.000004f2) have lower power loss in comparison with iron–phosphate composites (P = 0.00002f2).
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Eddy current and total power loss separation in the iron–phosphate–Polyepoxy soft magnetic composites
Materials & Design, 2009Co-Authors: Amir Hossei Taghvaei, H Shokrollahi, Kamal Janghorban, H AbiriAbstract:Abstract This work investigates the magnetic properties of iron–phosphate–Polyepoxy soft magnetic composite materials. FTIR spectra, EDX analysis, distribution maps, X-ray diffraction pattern and density measurements show that the particles surface layer contains a thin layer of nanocrystalline/amorphous phosphate with high coverage of powders surface. In this paper, a formula for calculating the eddy current loss and total loss components by loss separation method is presented and finally the different parts of power losses are calculated. The results show that, the contribution of eddy current in the bulk material for single coating layer (kb = 0.18) is higher in comparison with double coating layer (kb = 0.09). Moreover, iron–phosphate–Polyepoxy composites (P = 0.000004f2) have lower power loss in comparison with iron–phosphate composites (P = 0.00002f2).
Colette Lacabanne - One of the best experts on this subject based on the ideXlab platform.
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Electrical conductivity improvement of aeronautical carbon fiber reinforced Polyepoxy composites by insertion of carbon nanotubes
Journal of Non-Crystalline Solids, 2012Co-Authors: Antoine Lonjon, Philippe Demont, Eric Dantras, Colette LacabanneAbstract:An increase and homogenization of electrical conductivity is essential in epoxy carbon fiber laminar aeronautical composites. Dynamic conductivity measurements have shown a very poor transversal conductivity. Double wall carbon nanotubes have been introduced into the epoxy matrix to increase the electrical conductivity. The conductivity and the degree of dispersion of carbon nanotubes in epoxy matrix were evaluated. The epoxy matrix was filled with 0.4 wt.% of CNTs to establish the percolation threshold. A very low value of carbon nanotubes is crucial to maintain the mechanical properties and avoid an overload of the composite weight. The final carbon fiber aeronautical composite realized with the carbon nanotubes epoxy filled was studied. The conductivity measurements have shown a large increase of the transversal electrical conductivity. The percolative network has been established and scanning electron microscopy images confirm the presence of the carbon nanotube conductive pathway in the carbon fiber ply. The transversal bulk conductivity has been homogenized and improved to 10−1 S*m−1 for a carbon nanotubes loading near 0.12 wt.%.
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Influence of Vacuum and Temperature During Simulated Aging on Properties of a Polyepoxy Adhesive Used in Spacecraft Applications
53rd AIAA ASME ASCE AHS ASC Structures Structural Dynamics and Materials Conference<BR>20th AIAA ASME AHS Adaptive Structures Conference<BR&g, 2012Co-Authors: Nicolas Caussé, Colette Lacabanne, Claire Tonon, Eric Dantras, Pascale Guigue, Hélène Combes, Mathieu ChevalierAbstract:Adhesively bonded joints used on spacecraft are subject to thermal cycling in orbit. Effect of this ageing is investigated in terms of Polyepoxy adhesive properties and corresponding assemblies. A simplified isothermal ageing model is used to understand effect of temperature and secondary vacuum. Vacuum involves the same ageing phenomena than an ageing under neutral gaseous environment at atmospheric pressure. Temperature induces a post-curing of the adhesive. For the highest ageing temperature, a plasticization phenomenon is observed (glass transition temperature decrease). Thermal cycling leads to adhesive’s properties modifications similar to those monitored after an isothermal ageing. The effect of thermal cycle mainly depends on maximum temperature reached during a thermal cycle.
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Physical properties of CNTs-Polyepoxy nanocomposites: Influence of CNTs surface treatments
Revue internationale de génie électrique, 2009Co-Authors: Antoine Lonjon, Sophie Barrau, Eric Dantras, Philippe Demont, Colette LacabanneAbstract:Polymeric matrix nanocomposites provide great opportunities to overcome macroscopic properties of polymers. The shape factor of nanofillers is a key parameter, so carbon nanotubes (CNTs) have attracted much interest. To avoid aggregation, mechanical stirring has been used. In those conditions, the percolation threshold of conductivity is reached at 0.15 wt % for CNTs. To improve the shape factor, amphiphilic molecules have been successfully used: in this case, the percolation threshold is at 0.04 wt % for CNTs. After the percolation threshold, such nanocomposites allow the elimination of electric charges, while keeping the same mechanical properties than the polymeric matrix.
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Propriétés physiques de nanocomposites NTC-Polyepoxy: influence du traitement de surface des NTC
2009Co-Authors: Antoine Lonjon, Sophie Barrau, Eric Dantras, Philippe Demont, Colette LacabanneAbstract:Polymeric matrix nanocomposites provide great opportunities to overcome macroscopic properties of polymers. The shape factor of nanofillers is a key parameter, so carbon nanotubes (CNTs) have attracted much interest. To avoid aggregation, mechanical stirring has been used. In those conditions, the percolation threshold of conductivity is reached at 0.15 wt % for CNTs. To improve the shape factor, amphiphilic molecules have been successfully used: in this case, the percolation threshold is at 0.04 wt % for CNTs. After the percolation threshold, such nanocomposites allow the elimination of electric charges, while keeping the same mechanical properties than the polymeric matrix. RESUME : Les nanocomposites a matrice polymere offrent de nouvelles opportunites pour ameliorer les proprietes macroscopiques des polymeres. Le facteur de forme des nanocharges est un parametre cle, ce qui constitue le grand interet des nanotubes de carbone (NTC). Afin d’eviter les phenomenes d’agregation un melange mecanique a ete utilise. Dans ces conditions, le seuil de percolation electrique est de 0.15% en masse. Pour augmenter le facteur de forme, des molecules amphiphiles ont ete utilisees : dans ce cas le seuil de percolation est de 0.04% en masse. Au dessus du seuil de percolation, ces nanocomposites permettent l’ecoulement des charges electrostatiques tout en conservant les proprietes mecaniques de la matrice.
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DC and AC Conductivity of Carbon Nanotubes−Polyepoxy Composites
Macromolecules, 2003Co-Authors: Sophie Barrau, Christophe Laurent, Alain Peigney, Philippe Demont, Colette LacabanneAbstract:The dc and ac conductivities of carbon nanotubes−Polyepoxy composites have been investigated from 20 to 110 °C in the frequency range 10-2−106 Hz as a function of the conductive weight fraction p ranging from 0.04 to 2.5 wt %. The frequency dependence of the measured conductivity obeys the universal dynamic response (UDR): a dc plateau followed, above a critical frequency ωc, by the ωs power law with exponent s 0.6−1. The dc conductivity follows a percolation scaling law: σdc (p − pc)t with pc = 0.3 wt % and t = 1.4−1.8, according to the temperature. σdc reached 10-4 S/cm for 2.5 wt % CNTs content and increases with increasing temperature. Considering a biased random walk in three dimensions approach, we may explain the scaling law of ωc with p and its proportionality to σdc. The universality of ac conduction in carbon nanotubes−polymer composites is examined by the construction of master curves.
M Okada - One of the best experts on this subject based on the ideXlab platform.
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Modified Human Ureter and Human Saphenous Vein Grafts Tanned with a Polyepoxy Compound or Glutaraldehyde for Small-Diameter Arterial Substitution An Experimental Study
Vascular Surgery, 2000Co-Authors: Masahisa Uematsu, M OkadaAbstract:The Polyepoxy compound is a new cross-linking agent that is now replacing glutaraldehyde, and human ureter is a new potential substitute for small-caliber arterial prostheses. The present study was performed to compare the use of human ureter grafts tanned with a Polyepoxy compound, human ureter grafts tanned with glutaraldehyde, and human saphenous vein grafts tanned with a Polyepoxy compound for small-diameter arterial substitutions. Human ureter grafts tanned with a Polyepoxy compound (n=eight), human ureter grafts tanned with glutaraldehyde (n=six), and human saphenous vein grafts tanned with a Polyepoxy compound (n=eight) were implanted in the carotid arteries of Japanese white rabbits. These grafts were sacrificed after either 1 month's or 6 months' observation. There was no evidence of rejection, aneurysmal formation, and/or infection. Human ureter grafts tanned with a Polyepoxy compound after 1 month's observation (n=six) showed excellent patency without stenosis at the anastomotic sites as well as function, and the histologic findings revealed monolayer endothelial-like cells covering the surface of the graft. Human ureter grafts tanned with glutaraldehyde after 1 month's observation (n=six) were completely occluded with severe intimal hyperplasia. Human saphenous vein grafts tanned with a Polyepoxy compound after 1 month's observation (n= six) were patent at the time of explantation, but moderate stenosis caused bv intimal hyperplasia at the anastomotic sites was observed. The preliminary data also suggest that, with longer observation of up to 6 months, human ureter grafts tanned with a Polyepoxy compound (n=two) showed excellent patency. However, a longer observation of up to 6 months for human saphenous vein grafts tanned with a Polyepoxy compound (n=two) revealed severe intimal hyperplasia with intramural thrombosis and/or severe calcification. This study suggests that human ureter grafts tanned with a Polyepoxy compound could serve as more satisfactory bioprostheses for the reconstruction of small-caliber vessels than human ureter grafts tanned with glutaraldehyde or human saphenous vein grafts tanned with a Polyepoxy compound.
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A modified human ureter graft tanned by a new crosslinking agent Polyepoxy compound for small diameter arterial substitutions: an experimental preliminary study.
Artificial Organs, 1998Co-Authors: Masahisa Uematsu, M OkadaAbstract:The effectiveness of human ureter grafts tanned by Polyepoxy compound for small diameter arterial substitution was examined in 8 carotid arteries of rabbits, followed by an observation period of either 1 month (n = 6) or 6 months (n = 2). In this model there was no evidence of rejection, aneurysm formation, or infection. The modified human ureter showed excellent patency in all cases as well as excellent function, and the histological evaluation revealed monolayer endothelial-like cells covering all of the surface of the graft as was expected. No intimal hyperplasia was demonstrated at either anastomotic site. This study suggests that our newly designed Polyepoxy compound fixed human ureter could serve as a satisfactory blood conduit with good long-term patency for substitution.
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Experimental studies on modified human ureter as an arterial substitution for reconstruction of small caliber vessels.
The Kobe journal of medical sciences, 1996Co-Authors: Mitsugu Uematsu, M OkadaAbstract:Human ureters were experimentally employed as vascular biografts for small-caliber vessels. They were produced by tanning with Polyepoxy compound or glutaraldehyde, and also were compared with saphenous veins tanned by Polyepoxy compound and/or ready-made vascular graft of polytetrafluoroethylene (e-PTFE). These produced grafts, which had enough elasticity and excellent durability were successfully implanted to the carotid arteries in Japanese white rabbits. The grafts were sacrificed after 1 month observation. In this model there were no evidence of rejection, aneurysmal formation and/or infection. Polyepoxy compound fixed human ureter (n = 6), Polyepoxy compound fixed saphenous vein (n = 6) and e-PTFE (n =3) showed good patency, but all glutaraldehyde fixed human ureters (n = 3) were completely occluded with severe intimal hyperplasia. Especially, Polyepoxy compound fixed human ureter showed excellent patency as well as function, and the histological findings revealed monolayer endothelial cells covering the surface of the graft. No intimal hyperplasia was demonstrated at the anastomotic site. This study suggested that the Polyepoxy compound fixed human ureter could serve as a satisfactory blood conduit of reconstruction for the small caliber vessels. Our preliminary data also suggests that longer observation up to 6 months in Polyepoxy compound fixed human ureter graft and 18 months in Polyepoxy compound fixed saphenous vein graft after surgery, arteriovenous shunt (A-V shunt), long bypass with a graft length of 2 to 5 cm), Y-graft model, sequential model and reinforcement graft by dacron cloth give good results.
Hamid Kaddami - One of the best experts on this subject based on the ideXlab platform.
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Short date palm tree fibers/Polyepoxy composites prepared using RTM process: effect of tempo mediated oxydation of the fibers.
Bioresources, 2010Co-Authors: Adil Sbiai, Abderrahim Maazouz, Etienne Fleury, Henry Sautereau, Hamid KaddamiAbstract:Short date palm tree lignocellulosic fibers were used as a reinforcing phase in a Polyepoxy thermoset commodity resin. Unmodified fibers as well as counterparts chemically oxidized using TEMPO catalyst mediation were used as fillers for composite materials prepared in a Resin Transfer Molding process. The preparation was facilitated in the case of the composites based on oxidized fibers. During the process, the front displacement of injected resin was more regular, more homogeneous, and faster in the case of oxidized fibers. The morphology, thermal and mechanical properties of the resultant composites were characterized by SEM, DSC, DMA, as well as three-point bending and Charpy impact tests. An elevated reinforcing capability of the oxidized fibers as compared to their unmodified counterparts was demonstrated, particularly by a high strain test in the glassy state. This confirmed the enhanced filler/matrix interface observed in such materials during the process and in the final composite as analyzed by SEM. No significant difference in reinforcing capability of the two kinds of filler was observed in the DMA analysis.
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SHORT DATE PALM TREE FIBERS Polyepoxy COMPOSITES PREPARED USING RTM PROCESS: EFFECT OF TEMPO MEDIATED OXYDATION OF THE FIBERS
Bioresources, 2010Co-Authors: Adil Sbiai, Abderrahim Maazouz, Etienne Fleury, Henry Sautereau, Hamid KaddamiAbstract:Short date palm tree lignocellulosic fibers were used as a reinforcing phase in a Polyepoxy thermoset commodity resin. Unmodified fibers as well as counterparts chemically oxidized using TEMPO catalyst mediation were used as fillers for composite materials prepared in a Resin Transfer Molding process. The preparation was facilitated in the case of the composites based on oxidized fibers. During the process, the front displacement of injected resin was more regular, more homogeneous, and faster in the case of oxidized fibers. The morphology, thermal and mechanical properties of the resultant composites were characterized by SEM, DSC, DMA, as well as three-point bending and Charpy impact tests. An elevated reinforcing capability of the oxidized fibers as compared to their unmodified counterparts was demonstrated, particularly by a high strain test in the glassy state. This confirmed the enhanced filler/matrix interface observed in such materials during the process and in the final composite as analyzed by SEM. No significant difference in reinforcing capability of the two kinds of filler was observed in the DMA analysis.
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SHORT DATE PALM TREE FIBERS / Polyepoxy COMPOSITES PREPARED USING RTM PROCESS: EFFECT OF TEMPO MEDIATED OXIDATION OF THE FIBERS
North Carolina State University, 2010Co-Authors: Adil Sbiai, Abderrahim Maazouz, Etienne Fleury, Henry Sautereau, Hamid KaddamiAbstract:Short date palm tree lignocellulosic fibers were used as a reinforcing phase in a Polyepoxy thermoset commodity resin. Unmodified fibers as well as counterparts chemically oxidized using TEMPO catalyst mediation were used as fillers for composite materials prepared in a Resin Transfer Molding process. The preparation was facilitated in the case of the composites based on oxidized fibers. During the process, the front displacement of injected resin was more regular, more homogeneous, and faster in the case of oxidized fibers. The morphology, thermal and mechanical properties of the resultant composites were characterized by SEM, DSC, DMA, as well as three-point bending and Charpy impact tests. An elevated reinforcing capability of the oxidized fibers as compared to their unmodified counterparts was demonstrated, particularly by a high strain test in the glassy state. This confirmed the enhanced filler/matrix interface observed in such materials during the process and in the final composite as analyzed by SEM. No significant difference in reinforcing capability of the two kinds of filler was observed in the DMA analysis