References of "Thomassin, Jean-Michel"
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See detailHybrid material for electromagnetic absorption
Detrembleur, Christophe ULg; Huynen, Isabelle; Thomassin, Jean-Michel ULg et al

Patent (2012)

The present invention relates to a hybrid material (10) for absorbing electromagnetic radiation (60) and a method for making such a material. The hybrid material (10) comprises at least one grid panel (20 ... [more ▼]

The present invention relates to a hybrid material (10) for absorbing electromagnetic radiation (60) and a method for making such a material. The hybrid material (10) comprises at least one grid panel (20) of thickness t 1 having holes (25) traversing said thickness t 1 , at least one polymer composite material (30) of thickness t 2 filling at least partially the holes (25) of the at least one grid panel (20), said at least one polymer composite material (30) including a polymer matrix (40) and conductive particles (50) dispersed into said polymer matrix (40), characterized in that the internal surface of the holes (25) of the at least one grid panel (20) is metallic. [less ▲]

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See detailProcess for preparing electromagnetic interference shileding materials
Thomassin, Jean-Michel ULg; Jérôme, Christine ULg; Detrembleur, Christophe ULg et al

Patent (2012)

The present invention relates to a process for preparing an electromagnetic interference shielding material, or a precursor thereof, comprising a first polymer matrix and carbon conductive loads, said ... [more ▼]

The present invention relates to a process for preparing an electromagnetic interference shielding material, or a precursor thereof, comprising a first polymer matrix and carbon conductive loads, said process comprises the steps of: (a) Forming a reaction mixture comprising carbon conductive loads and a polymerizable medium said polymerizable medium comprising one or more monomers dissolved in a solvent, (b) Exposing the reaction mixture to polymerization conditions to polymerize said polymerizable medium and thus form a polymer, and (c) Forming a precipitate or an agglomerate of an electromagnetic interference shielding material made of less than 50 wt.% carbon conductive loads dispersed in the first polymer matrix formed in step (b), characterized in that, said polymer is insoluble in said solvent and in that a fraction of the polymer chains thus formed are grafted on part of the surface of the carbon conductive loads. [less ▲]

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See detailProcess for preparing electromagnetic interference shileding materials
Thomassin, Jean-Michel ULg; Jérôme, Christine ULg; Detrembleur, Christophe ULg et al

Patent (2012)

The present invention relates to a process for preparing an electromagnetic interference shielding material, or a precursor thereof, comprising a first polymer matrix and carbon conductive loads, said ... [more ▼]

The present invention relates to a process for preparing an electromagnetic interference shielding material, or a precursor thereof, comprising a first polymer matrix and carbon conductive loads, said process comprises the steps of: (a) Forming a reaction mixture comprising carbon conductive loads and a polymerizable medium said polymerizable medium comprising one or more monomers dissolved in a solvent, (b) Exposing the reaction mixture to polymerization conditions to polymerize said polymerizable medium and thus form a polymer, and (c) Forming a precipitate or an agglomerate of an electromagnetic interference shielding material made of less than 50 wt.% carbon conductive loads dispersed in the first polymer matrix formed in step (b), characterized in that, said polymer is insoluble in said solvent and in that a fraction of the polymer chains thus formed are grafted on part of the surface of the carbon conductive loads. [less ▲]

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See detailElectromagnetic absorption properties of carbon nanotube nanocomposite foam filling honeycomb waveguide structures
Quiévy, Nicolas; Bollen, Pierre; Thomassin, Jean-Michel ULg et al

in IEEE Transactions on Electromagnetic Compatibility (2012), 24(1), 43-51

Carbon nanotube reinforced polymer foams filling a metallic honeycomb were processed and characterized for the production of hybrid materials with high electromagnetic absorption potential ... [more ▼]

Carbon nanotube reinforced polymer foams filling a metallic honeycomb were processed and characterized for the production of hybrid materials with high electromagnetic absorption potential. Electromagnetic modeling and experimental characterization of the hybrids proved that the honeycomb, acting as a hexagonal waveguide, improves the absorption properties in the gigahertz range above the cutoff frequency. The electromagnetic absorption can be tuned by changing the hybrid material properties. The required levels of electrical conductivity are attained owing to the dispersion of low amounts (1–2 wt%) of carbon nanotubes inside the polymermatrix. The combination of the foam and honeycomb architecture contributes to decrease the real part of the relative effective permittivity Re{εr,eff }. Varying the cell shape of the honeycomb changes the frequency range for high absorption. An analytical model for the absorption has been developed, showing good agreement with the experimental results. [less ▲]

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See detailA convenient route for the dispersion of carbon nanotubes in polymers: Application to the preparation of electromagnetic interference (EMI) absorbers
Thomassin, Jean-Michel ULg; Vuluga, Daniela; Alexandre, Michaël ULg et al

in Polymer (2012), 53(1), 169-174

A new dispersion technique has been implemented which consists in the polymerization of a monomer in the presence of CNTs in a bad solvent of the polymer. During its formation, the polymer precipitates ... [more ▼]

A new dispersion technique has been implemented which consists in the polymerization of a monomer in the presence of CNTs in a bad solvent of the polymer. During its formation, the polymer precipitates and entraps all the CNTs. Thanks to the establishment of a suitable CNTs dispersion, this method promotes much higher electrical conductivity in the resulting nanocomposite than more conventional techniques, i.e. melt-mixing and co-precipitation. Moreover, the quantity of solvent required is much lower than in the co-precipitation method that makes this process industrially viable. One potential application of these nanocomposites has been demonstrated by the preparation of foams using the supercritical CO2 technology that present very high electromagnetic interference (EMI) absorbing properties since more than 90% of the incoming power being absorbed in the foam. [less ▲]

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See detailThermo-reversible reactions for the preparation of smart materials: recyclable covalently-crosslinked shape memory polymers
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

in Macromolecular Symposia (2011), 309/310(1), 154-161

[4+2] thermoreversible Diels-Alder cycloaddition has been used to crosslink star-shaped poly(ε-caprolactone) in order to produce networks based on strong carbon-carbon covalent bondings. Depending on the ... [more ▼]

[4+2] thermoreversible Diels-Alder cycloaddition has been used to crosslink star-shaped poly(ε-caprolactone) in order to produce networks based on strong carbon-carbon covalent bondings. Depending on the nature of the Diels-Alder reactants, these bonds can be thermoreversibly broken, allowing re-processing of the polymer matrix. [less ▲]

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See detailCaractérisation microstructurale de mousses polymères nanocomposites par microtomographie à rayons X
Plougonven, Erwan ULg; Tran, Minh Phuong ULg; Marchot, Pierre ULg et al

Poster (2011, November 29)

Les circuits électriques, fonctionnant à des fréquences de plus en plus élevées, sont responsables de l’augmentation de la pollution électromagnétique, et justifient le développement de blindages ... [more ▼]

Les circuits électriques, fonctionnant à des fréquences de plus en plus élevées, sont responsables de l’augmentation de la pollution électromagnétique, et justifient le développement de blindages efficaces. De nombreuses applications sont concernées, que ce soit dans les systèmes électroniques commerciaux, industriels, ou militaires, ou les systèmes antennaires. Récemment, des blindages sous forme de composites polymère/charges carbonées ont été largement développés pour leur nombreux avantages : plus légers, moins chers, plus absorbants, et plus facilement moulables. Une charge carbonée prometteuse est le nanotube de carbone car de par son facteur de forme, une concentration moindre est nécessaire pour une conductivité équivalente [1]. Afin d’améliorer l’absorption de l’énergie électromagnétique de ces composites (par rapport à leur réflectivité), ils sont moussés pour réduire leur constante diélectrique. Cette étape de moussage doit être rigoureusement contrôlée pour atteindre le niveau d’absorption ciblé. Deux techniques de moussage sont envisagées dans cette étude, à savoir le moussage en CO2 supercritique (par imprégnation de CO2 en condition supercritique, avant une dépressurisation rapide) et le freeze-drying (dissolution dans un solvant, suivi d’une lyophilisation de celui-ci). Ces deux méthodes génèrent des structures de porosité bien distinctes, avec une anisotropie apparente marquée dans le second cas. L’objectif est de caractériser ces structures par tailles moyennes de pores et mesures d’anisotropie, et leur lien avec l’efficacité de blindage. Dans cette optique, la caractérisation est effectuée par microtomographie à rayons X, une technique d’imagerie 3D non-destructive. Des acquisitions sont faites sur chaque échantillon, et la microstructure est analysée par traitement d’images. Vu la très faible atténuation des rayons X dans ce type de matériaux, et la limite de résolution de cette technique par rapport à la taille des pores et à l’épaisseur des parois, la séparation précise des pores par rapport à la matrice polymère s’avère difficile. Une segmentation classique n’étant pas applicable en préalable à des mesures quantitatives, la fonction d’autocorrélation est utilisée. Cette technique, habituellement utilisée en traitement du signal, est une méthode performante de mesure globale de l’anisotropie d’un matériau [2]. Elle permet également d’extraire une longueur caractéristique qui peut être liée à la taille des cellules. Les résultats mettent en évidence l’impact de la technique et des conditions de moussage sur la microstructure des mousses composites. [less ▲]

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See detailInfluence of nanoparticle-polymer interactions on the apparent migration behaviour of carbon nanotubes in an immiscible polymer blend
Tao, Fangfang; Nysten, Bernard; Baudouin, Anne-Christine et al

in Polymer (2011), 52(21), 4798-4805

We investigate the influence of nanoparticle–polymer interactions on the apparent migration behavior of multiwall carbon nanotubes (CNTs) in an immiscible polymer blend of ethylene-acrylate copolymer (EA ... [more ▼]

We investigate the influence of nanoparticle–polymer interactions on the apparent migration behavior of multiwall carbon nanotubes (CNTs) in an immiscible polymer blend of ethylene-acrylate copolymer (EA) and polyamide 12 (PA). The polymer-CNTs interaction is tuned by using different surface modification strategies, comprising grafting and coating. Poly(methyl methacrylate) (PMMA) and polystyrene (PS) are chosen as surface modifiers. The nanocomposite materials are prepared by melt-blending polymer-modified-CNTs in EA and PA. Polymer-grafted-CNTs tend to concentrate at the PA/EA interface, even if predispersed in PA, as opposed to pristine CNTs, which stay inside PA under the same circumstances. This new behavior is consistent with the morphology of PA/EA/(PMMA or PS) ternary blends and suggest a dominance of interfacial thermodynamics on CNTs localization. If we use polymer-coated-CNTs instead, the behavior depends on molar mass of the coating polymer. For low molar mass, it is similar to that of pristine CNTs and indicates desorption of the coating, owing to the weak interaction with the CNTs surface. Interestingly, we observe that long PS chains do not desorb and can drive the CNTs to the interface of the PA/EA blend. Moreover, the influence of kinetics is clearly observed through the dependence of CNTs interfacial confinement on dispersed droplet size. [less ▲]

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See detailPMMA/ carbon nanotube nanocomposite foams for EMI shielding application
Thomassin, Jean-Michel ULg; Vuluga, Daniela; Huynen, Isabelle et al

Conference (2011, August 30)

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See detailDesign of cross-linked semicrystalline poly(ε-caprolactone)-based networks with one-way and two-way shape-memory properties through Diels–Alder
Raquez, Jean-Marie; Vanderstappen, Sophie; Meyer, Franck et al

in Chemistry : A European Journal (2011), 17(36), 10135-10143

Cross-linked poly(ε-caprolactone) (PCL)-based polyesterurethane (PUR) systems have been synthesized through Diels–Alder reactions by reactive extrusion. The Diels–Alder and retro-Diels–Alder reactions ... [more ▼]

Cross-linked poly(ε-caprolactone) (PCL)-based polyesterurethane (PUR) systems have been synthesized through Diels–Alder reactions by reactive extrusion. The Diels–Alder and retro-Diels–Alder reactions proved to be useful for enhancing the molecular motion of PCL-based systems, and therefore their crystallization ability, in the design of cross-linked semicrystalline polymers with one-way and two-way shape-memory properties. Successive reactions between alpha,omega-diol PCL (PCL2), furfuryl alcohol, and methylene diphenyl 4,4′-diisocyanate straightforwardly afforded the alpha,omega-furfuryl PCL-based PUR systems, and subsequent Diels–Alder reactions with N,N-phenylenedimaleimide afforded the thermoreversible cycloadducts. The cross-linking density could be modulated by partially replacing PCL-diol with PCL-tetraol. Interestingly, the resulting PUR systems proved to be semicrystalline cross-linked polymers, the melting temperature of which (close to 45 °C) represented the switching temperature for their shape-memory properties. Qualitative and quantitative measurements demonstrated that these PUR systems exhibited one-way and two-way shape-memory properties depending on their cross-linking density. [less ▲]

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See detailPMMA/carbon nanotube nanocomposites foams for EMI shielding application
Thomassin, Jean-Michel ULg; Molenberg, Isabel; Huynen, Isabelle et al

Conference (2011, June 27)

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See detailAn efficient biphasic synthesis of polymer-grafted reduced graphite oxide based nanocomposites
Vuluga, Daniela ULg; Thomassin, Jean-Michel ULg; Molenberg, Isabel et al

Conference (2011, June 01)

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See detailProgress in cobalt-mediated radical polymerization
Debuigne, Antoine ULg; Hurtgen, Marie ULg; Piette, Yasmine ULg et al

Poster (2011, May 12)

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See detailMultifunctional hybrids for electromagnetic absorption
Huynen, Isabelle; Quievy, N.; Bailly, Christian et al

in Acta Materialia (2011), 59(8), 3255-3266

Electromagnetic (EM) interferences are ubiquitous in modern technologies and impact on the reliability of electronic devices and on living cells. Shielding by EM absorption, which is preferable over ... [more ▼]

Electromagnetic (EM) interferences are ubiquitous in modern technologies and impact on the reliability of electronic devices and on living cells. Shielding by EM absorption, which is preferable over reflection in certain instances, requires combining a low dielectric constant with high electrical conductivity, which are antagonist properties in the world of materials. A novel class of hybrid materials for EM absorption in the gigahertz range has been developed based on a hierarchical architecture involving a metallic honeycomb filled with a carbon nanotube-reinforced polymer foam. The waveguide characteristics of the honeycomb combined with the performance of the foam lead to unexpectedly large EM power absorption over a wide frequency range, superior to any known material. The peak absorption frequency can be tuned by varying the shape of the honeycomb unit cell. A closed form model of the EM reflection and absorption provides a tool for the optimization of the hybrid. This designed material sets the stage for a new class of sandwich panels combining high EM absorption with mass efficiency, stiffness and thermal management. [less ▲]

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