References of "Thomassin, Jean-Michel"
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See detailCarbon nanotubes/polypropylene nanocomposites foams for EMI shielding applications
Tran, Minh Phuong ULg; Detrembleur, Christophe ULg; Thomassin, Jean-Michel ULg et al

Conference (2013, September 12)

In order to reduce the undesired effect of the electromagnetic interference, the developing of the materials with high capacity of electromagnetic interference (EMI) shielding has attracted a great ... [more ▼]

In order to reduce the undesired effect of the electromagnetic interference, the developing of the materials with high capacity of electromagnetic interference (EMI) shielding has attracted a great attention to scientific and industrial communities during last two decades.Indeed, polymer carbon nanotubes (CNTs) nanocomposites foams are addressed due to their high electrical conductivity and a great potential applications in electrostatic dissipation (ESD) and in electromagnetic interferences (EMI) shielding. However, the shortcoming of the addition of CNTs is that it usually leads to an increase of permittivity which results in enhancing undesirably the electromagnetic reflectivity due to the mismatch between the wave impedances for the signal propagating into air and into the absorbing material, respectively. To solve this problem, the introduction of air into these nanocomposites by the formation of foam will be favorable in order to reduce the permittivity of conductive composites. A good understanding of the influence of the foam structural parameters on the electrical properties of the foam will ultimately enable the optimum design of these materials for the targeted applications. A wide range of poly (propylene)/CNTs nanocomposites foams were synthesized using the supercritical CO2 technology. Different foaming parameters, such as the temperature, impregnation pressure will be controlled to modify the foam structure. Nanocomposite foams show higher electrical conductivity than non-foamed nanocomposites at the same volume content of CNTs. Effects of foam morphology such as cell density, pore size, volume expansion, and cell-wall thickness on electrical conductivity were comprehensively assessed. Similarly to our previous study on PMMA foam nanocomposites, the electrical conductivity of foams show higher value when the volume expansion is increased and when the average pore size is decreased. The preliminary EMI performances have highlighted that PP/CNTs foams containing 0.1 vol%CNTs are able to absorb about 90% of the incident radiation in the 25 to 40 GHz frequency range. [less ▲]

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See detailMorphology and electrical conductivity of poly(propylene)/multi-walled carbon nanotubes nanocomposites foams compatibilized by poly(propylene) -graft-maleic anhydride (PP-g-MA)
Tran, Minh Phuong ULg; Detrembleur, Christophe ULg; Alexandre, Michaël et al

Poster (2013, September 09)

The agglomerate of carbon nanotubes (CNTs) in poly(propylene) (PP) matrix often results in low electrical conductivity and poor mechanical properties. In order to improve the dispersion of CNTs, different ... [more ▼]

The agglomerate of carbon nanotubes (CNTs) in poly(propylene) (PP) matrix often results in low electrical conductivity and poor mechanical properties. In order to improve the dispersion of CNTs, different amounts of compatibilizer based on poly(propylene-graft-maleic anhydride) (PP-g-MA) were added in the PP matrix. Carbon nanotubes materbatches pre-dispersed at a high loading in the compatibilizer were used to create the samples used in this study. The nanocomposites of PP/PP-g-MA/CNTs were then foamed in supercritical carbon diozide (scCO2) followed by analysis of the foam morphology and the electrical conductivity. The presence of PPgMA did not significantly change the foam morphology, which exhibits good homogeneity and highly uniform closed-cells with penta-heptagonal cell-form. The expansion volume of the foams is not adversely affected by the addition of the compatibilizer; very high expansion volume (around 15 - 25 times) was achieved. The most interesting point is that the PP-PPgMA - 4wt%CNTs foams show a significantly higher electrical conductivity than the uncompatibilized PP-4wt%CNTs at the same volume percent content of CNTs [less ▲]

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See detailCharacterization and optimization of GMO-based gels with long term release for intraarticular administration
Réeff, J.; Gaignaux, A.; Goole, J. et al

in International Journal of Pharmaceutics (2013), 451(1-2), 95-103

Osteoarthritis is characterized by slow degenerative processes in the articular cartilage within synovial joints. It could be interesting to develop a sustained-release formulation that could be effective ... [more ▼]

Osteoarthritis is characterized by slow degenerative processes in the articular cartilage within synovial joints. It could be interesting to develop a sustained-release formulation that could be effective on both pain/inflammation and restoration of mechanical integrity of the joint. Recently, an injectable system based on glycerol monooleate (GMO), containing clonidine as a model hydrophilic analgesic/anti-inflammatory drug and hyaluronic acid as a viscoelastic scaffold, showed promising potential as a biodegradable and biocompatible preparation to sustain the drug activity. However, drug release from the system is relatively fast (complete within 1 week) and the underlying drug release mechanisms not fully understood. The aims of this study were: (i) to significantly improve this type of local controlled drug delivery system by further sustaining clonidine release, and (ii) to elucidate the underlying mass transport mechanisms. The addition of FDA-approved inactive ingredients such as sodium oleate or purified soybean oil was found to be highly effective. The release rate could be substantially reduced (e.g., 50% release after 10 days), due to the increased hydrophobicity of the systems, resulting in slower and reduced water uptake and reduced drug mobility. Interestingly, Fick's second law of diffusion could be used to quantitatively describe drug release. [less ▲]

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See detailPolymer/carbon based composites as electromagnetic interference (EMI) shielding materials
Thomassin, Jean-Michel ULg; Jérôme, Christine ULg; Pardoen, Thomas et al

in Materials Science & Engineering : R (2013), 74(7), 211-232

The extensive development of electronic systems and telecommunications has lead to major concerns regarding electromagnetic pollution. Motivated by environmental questions and by a wide variety of ... [more ▼]

The extensive development of electronic systems and telecommunications has lead to major concerns regarding electromagnetic pollution. Motivated by environmental questions and by a wide variety of applications, the quest for materials with high efficiency to mitigate electromagnetic interferences (EMI) pollution has become a mainstream field of research. This paper reviews the state-of-the-art research in the design and characterization of polymer/carbon based composites as EMI shielding materials. After a brief introduction, in Section 1, the electromagnetic theory will be briefly discussed in Section 2 setting the foundations of the strategies to be employed to design efficient EMI shielding materials. These materials will be classified in the next section by the type of carbon fillers, involving carbon black, carbon fiber, carbon nanotubes and graphene. The importance of the dispersion method into the polymer matrix (melt-blending, solution processing, etc.) on the final material properties will be discussed. The combination of carbon fillers with other constituents such as metallic nanoparticles or conductive polymers will be the topic of Section 4. The final section will address advanced complex architectures that are currently studied to improve the performances of EMI materials and, in some cases, to impart additional properties such as thermal management and mechanical resistance. In all these studies, we will discuss the efficiency of the composites/devices to absorb and/or reflect the EMI radiation. [less ▲]

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See detailThe influence of foam morphology of multi-walled carbon nanotubes/poly(methyl methacrylate) nanocomposites on electrical conductivity
Tran, Minh Phuong ULg; Detrembleur, Christophe ULg; Alexandre, Michaël ULg et al

in Polymer (2013), 54(13), 3261-3270

Polymer/multi-walled carbon nanotubes (PMMA/MWNTs) nanocomposites foams are widely investigated during the last decade thanks to their potential applications as electromagnetic interferences shielding ... [more ▼]

Polymer/multi-walled carbon nanotubes (PMMA/MWNTs) nanocomposites foams are widely investigated during the last decade thanks to their potential applications as electromagnetic interferences shielding (EMI) materials. Electrical conductivity of the nanocomposite is a key parameter for these applications. In the frame of this work, we aim at establishing relationships between the foams morphology and their electrical conductivity. We therefore first design nanocomposite foams of various morphologies using supercritical carbon dioxide (scCO2) as physical foaming agent. The nanocomposites based on poly(methyl methacrylate) (PMMA) and different carbon nanotubes loadings are prepared by melt-mixing and foamed by scCO2 in various conditions of pressure, temperature and soaking time. The influence of these foaming conditions on the morphology of the foams (volume expansion, pore size, cell density, cell-wall thickness) is discussed. After measuring the electrical conductivity of the foams, we establish structure/properties relationships that are essential for further optimizations of the materials for the targeted application. [less ▲]

Detailed reference viewed: 81 (27 ULg)
See detailUse of supercritical carbon dioxide to elaborate drug-loaded polymeric implants
Champeau, Mathilde; Thomassin, Jean-Michel ULg; Jérôme, Christine ULg et al

Poster (2013, April 25)

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See detailDielectric and rheological characterization of polymer/graphene oxide nano composites
Thomassin, Jean-Michel ULg; Trifkovic, Milana; Jérôme, Christine ULg et al

Conference (2013, April 05)

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See detailUse of supercritical carbon dioxide to elaborate drug-loaded polymeric implants
Champeau, Mathilde; Thomassin, Jean-Michel ULg; Jérôme, Christine ULg et al

Poster (2013, March 17)

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See detailMultifunctional architectured materials for electromagnetic absorption
Bollen, P.; Quiévy, N.; Huynen, I. et al

in Scripta Materialia (2013), 68(1), 50-54

A sandwich structure involving a honeycomb core filled with a carbon nanotube-reinforced polymer foam and glass fiber-reinforced composite face sheets has been developed in order to combine high ... [more ▼]

A sandwich structure involving a honeycomb core filled with a carbon nanotube-reinforced polymer foam and glass fiber-reinforced composite face sheets has been developed in order to combine high electromagnetic absorption and high mechanical performance. The large electromagnetic absorption is attained by simultaneously minimizing the reflection and transmission, which, in terms of effective material properties, requires a low dielectric constant and a conductivity around 1 S m−1. The sandwich offers also high stiffness versus density performance. [less ▲]

Detailed reference viewed: 52 (2 ULg)
See detailImprégnation de polymères par voie CO2 supercritique: suivi in situ par microscopie FTIR
Champeau, Mathilde; Thomassin, Jean-Michel ULg; Jérôme, Christine ULg et al

Conference (2012, September 15)

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See detailEffects of cellular morphology on electricalconductivity of carbon nanotubes containing nanocomposites foams
Tran, Minh Phuong ULg; Detrembleur, Christophe ULg; Thomassin, Jean-Michel ULg et al

Conference (2012, September 13)

In the last few years, polymer carbon nanotubes (CNTs) nanocomposites foams have received increasing attention due to their potential applications in electrostatic dissipation (ESD) and in electromagnetic ... [more ▼]

In the last few years, polymer carbon nanotubes (CNTs) nanocomposites foams have received increasing attention due to their potential applications in electrostatic dissipation (ESD) and in electromagnetic interferences (EMI) shielding. To be efficient, these foams must exhibit appropriate electrical conductivity (> 1 S/m) and dielectric constant. A good understanding of the influence of the foam structural parameters on the electrical properties of the foam will ultimately enable the optimum design of these materials for the targeted applications. A wide range of poly(methyl methacrylate) (PMMA)/CNTs nanocomposites foams were synthesized using the supercritical CO2 technology. Different foaming parameters, such as the temperature, impregnation pressure, time and rate of depressurization were varied to modify the foam structure. The amount of carbon nanotubes in PMMA plays the most important role in increasing the electrical conductivity. Nanocomposite foams show higher electrical conductivity than non-foamed nanocomposites at the same volume content of CNTs. Effects of foam morphology such as cell-density; pore size, volume expansion, and cell-wall thickness on electrical conductivity were comprehensively assessed. High electrical conductivity can be achieved with nanocomposite foams that have high volume expansion, small pore size, high cell density, and thin cell-walls [less ▲]

Detailed reference viewed: 39 (4 ULg)
See detailEffects of cellular morphology on electricalconductivity of carbon nanotubes containing nanocomposites foams
Tran, Minh Phuong ULg; Thomassin, Jean-Michel ULg; Alexandre, Michaël et al

Conference (2012, June 07)

In the last few years, polymer carbon nanotubes (CNTs) nanocomposites foams have received increasing attention due to their potential applications in electrostatic dissipation (ESD) and in electromagnetic ... [more ▼]

In the last few years, polymer carbon nanotubes (CNTs) nanocomposites foams have received increasing attention due to their potential applications in electrostatic dissipation (ESD) and in electromagnetic interferences (EMI) shielding. To be efficient, these foams must exhibit appropriate electrical conductivity (> 1 S/m) and dielectric constant. A good understanding of the influence of the foam structural parameters on the electrical properties of the foam will ultimately enable the optimum design of these materials for the targeted applications. A wide range of poly(methyl methacrylate) (PMMA)/CNTs nanocomposites foams were synthesized using the supercritical CO2 technology. Different foaming parameters, such as the temperature, impregnation pressure, time and rate of depressurization were varied to modify the foam structure. The amount of carbon nanotubes in PMMA plays the most important role in increasing the electrical conductivity. Nanocomposite foams show higher electrical conductivity than non-foamed nanocomposites at the same volume content of CNTs. Effects of foam morphology such as cell-density; pore size, volume expansion, and cell-wall thickness on electrical conductivity were comprehensively assessed. High electrical conductivity can be achieved with nanocomposite foams that have high volume expansion, small pore size, high cell density, and thin cell-walls [less ▲]

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See detailCrosslinking of star-shape PCLs through Diels-Alder reactions for the preparation of shape memory polymers
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

Poster (2012, May 10)

Poly(ε-caprolactone) (PCL), a semi-crystalline polymer, is one of the most widely studied polymers for the development of shape memory materials when chemically cross-linked. PCL presents several ... [more ▼]

Poly(ε-caprolactone) (PCL), a semi-crystalline polymer, is one of the most widely studied polymers for the development of shape memory materials when chemically cross-linked. PCL presents several advantages such as a melting transition temperature close to human body temperature, a high biocompatibility and is (bio)degradable. So, this polymer is highly relevant for both biomedical devices such as stents or resorbable suture wires and also for degradable packaging. However, after cross-linking, the material can not be reprocessed, preventing any reuse/recycling of the material. One of the purposes of this work is to find a solution to this major drawback, which would then allow, for example, to reshape packaging films after use or to recycle trimmings remaining after fabrication. Amongst current trends in the design of new polymer and composite materials, the use of organic reactions that are able to create and reversibly disrupt chemical bonds upon an external stimulus (temperature, irradiation,…) is currently gaining more and more attention as it can lead to applications in various areas such as remendable materials, drug delivery systems, stimulus-degrading materials or recyclable materials. This contribution aims at reporting a new concept for the preparation of well defined and recyclable PCL based reversibly cross-linked shape memory polymer by the formation of reversible carbon-carbon bonds. Amongst all the reversible links described in the literature, thermally (4+2) reversible cycloadditions present interesting features such as the creation of robust bonds and well defined reversibility conditions. As an example, the application of furan/maleimide adducts as covalent link, which cycloreversion is largely favored in the range of temperature (90-120°C), is widely reported. For this purpose, commercially-available star-shaped PCL precursors have been selected and selectively modified at their chain ends either by a diene (furan, anthracene) or a dienophile (maleimide). Typically, PCL-based shape memory materials have been prepared by mixing a stoichiometric amount of diene-bearing and maleimide-bearing PCLs in a twin-screw mini-extruder at a temperature which favors cycloreversion. The polymer blend is then cured at 65°C (just above PCL melting temperature), with the purpose to increase chains mobility and improve the formation of the adducts. Cross-linked PCLs were obtained, as evidenced by swelling experiments. The shape memory properties of the materials have been studied by cyclic tensile thermomechanical analysis. The influence of the nature of the Diels-Alder moieties on the cross-linking rate and on the shape memory properties has been studied. Reversibility of the network formation in the case of furan, used as diene, has been assessed by rheology and by recycling experiment. [less ▲]

Detailed reference viewed: 92 (6 ULg)