References of "Urbanczyk, Laetitia"
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See detailBatch foaming of SAN/clay nanocomposites with scCO2: A very tunable way of controlling the cellular morphology
Urbanczyk, Laetitia ULg; Calberg, Cédric ULg; Detrembleur, Christophe ULg et al

in Polymer (2010), 51(15), 3520-3531

This paper aims at elucidating some important parameters affecting the cellular morphology of poly(styrene-co-acrylonitrile) (SAN)/clay nanocomposite foams prepared with the supercritical CO2 technology ... [more ▼]

This paper aims at elucidating some important parameters affecting the cellular morphology of poly(styrene-co-acrylonitrile) (SAN)/clay nanocomposite foams prepared with the supercritical CO2 technology. Prior to foaming experiments, the SAN/CO2 system has first been studied. The effect of nanoclay on CO2 sorption/desorption rate into/from SAN is assessed with a gravimetric method. Ideal saturation conditions are then deduced in view of the foaming process. Nanocomposites foaming has first been performed with the one-step foaming process, also called depressurization foaming. Foams with different cellular morphology have been obtained depending on nanoclay dispersion level and foaming conditions. While foaming at low temperature (40 °C) leads to foams with the highest cell density (1012–1014 cells/cm3), the foam expansion is restricted (d0.7–0.8 g/cm3). This drawback has been overcome with the use of the two-step foaming process, also called solid-state foaming, where foam expansion occurs during sample dipping in a hot oil bath (d0.1–0.5 g/cm3). Different foaming parameters have been varied, and some schemes have been drawn to summarize the characteristics of the foams prepared – cell size, cell density, foam density – depending on both the foaming conditions and nanoclay addition. This result thus illustrates the huge flexibility of the supercritical CO2 batch foaming process for tuning the foam cellular morphology. [less ▲]

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See detailPreparation of fire-resistant poly(styrene-co-acrylonitrile) foams using supercritical CO2 technology
Urbanczyk, Laetitia ULg; Bourbigot, Serge; Calberg, Cédric ULg et al

in Journal of Materials Chemistry (2010), 20

This work deals with the preparation and characterization of fire-resistant poly(styrene coacrylonitrile) (SAN) foams containing (organo)clays and/or melamine polyphosphate (MPP) as fire retardants using ... [more ▼]

This work deals with the preparation and characterization of fire-resistant poly(styrene coacrylonitrile) (SAN) foams containing (organo)clays and/or melamine polyphosphate (MPP) as fire retardants using supercritical CO2 as the foaming agent. The additives dispersion was first characterized with X-ray and transmission electron microscopy (TEM) analyses. Their presence clearly affected the cellular morphology, as observed by scanning electron microscopy (SEM). Then, the peak of heat release rate (PHRR) and total heat evolved (THE) were determined with a cone calorimetry test, performed on each foamed sample as a function of the foam density. Incorporation of clay (3 and 5 wt%) in the exfoliated state into the SAN foam clearly led to a significant decrease of PHRR, while intercalated and aggregated clay had a lower effect. Similar results were obtained with 10 and 20 wt% of MPP. The best results were obtained when exfoliated clay and MPP were combined, with a PHRR drop as large as 75%, thanks to the synergistic action of both additives. The magnitude of PHRR drop, related to the fire resistance, was found to be in direct relationship with the cohesiveness of the protective carbonaceous layer formed at the sample surface during combustion. Clay and MPP, when added together, are thus believed to favour the formation of a highly cohesive protective layer able to act as an efficient shield against the flame, despite the fact that the sample is originally composed of ~90% of voids. [less ▲]

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See detailMorphology and properties of SAN-clay nanocomposites prepared principally by water-assisted extrusion
Mainil, Michaël; Urbanczyk, Laetitia ULg; Calberg, Cédric ULg et al

in Polymer Engineering & Science (2010), 50(1), 10-21

An efficient extrusion process involving the injection of water while processing was used to prepare poly(styrene-co-acrylonitrile) (SAN) / clay nanocomposites with a high degree of nanoclay delamination ... [more ▼]

An efficient extrusion process involving the injection of water while processing was used to prepare poly(styrene-co-acrylonitrile) (SAN) / clay nanocomposites with a high degree of nanoclay delamination. The usefulness of water-assisted extrusion is highlighted here, in comparison with classical extrusion and roll mill processes. Cloisite® 30B (C30B), a montmorillonite clay organomodified with alkylammonium cations bearing 2-hydroxyethyl chains, and pristine montmorillonite were melt blended with SAN (25wt% AN) in a semi-industrial scale extruder specially designed to allow water injection. XRD analysis, visual and TEM observations were used to evaluate the quality of clay dispersion. The relationship between the nanocomposite morphology and its mechanical and thermal properties was then investigated. The superiority of the SAN/C30B nanocomposite extruded with water has been evidenced by cone calorimetry tests and thermogravimetric measurements (TGA). These analyses showed a substantial improvement of the fire behavior and the thermal properties, while a 20% increase of the Young modulus was recorded. [less ▲]

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See detailFoams of polyurethane/MWNT nanocomposites for efficient EMI reduction
Chen, Y. Y.; Urbanczyk, Laetitia ULg; Thomassin, Jean-Michel ULg et al

Poster (2009, September 16)

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See detailProduction of polymer/clay nanocomposite foams with improved fire behaviour using supercritical fluid technology
Urbanczyk, Laetitia ULg; Calberg, Cédric ULg; Detrembleur, Christophe ULg et al

Poster (2009, June 19)

In this study, supercritical CO2 is successfully used as foaming agent to prepare poly(styrene-co-acrylonitrile) (SAN) foams containing a low amount of well-dispersed nanoclay (5wt%). This kind of ... [more ▼]

In this study, supercritical CO2 is successfully used as foaming agent to prepare poly(styrene-co-acrylonitrile) (SAN) foams containing a low amount of well-dispersed nanoclay (5wt%). This kind of nanofiller has an influence both on material cellular morphology and fire property. In fact, SAN foam filled with nanoclay has smaller cells and higher density compared to unfilled foam. Moreover, the nanocomposite foam burns more slowly and without producing any burning droplets, which is highly desirable when considering housing applications. [less ▲]

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See detailUse of the supercritical fluid technology to prepare efficient nanocomposite foams for environmental protection purpose
Urbanczyk, Laetitia ULg; Thomassin, Jean-Michel ULg; Huynen, Isabelle et al

Conference (2009, May 19)

This work reports on the preparation of novel nanocomposite foams that are efficient broadband microwave absorbers. Carbon nanotubes are first successfully dispersed into PCL and PMMA by melt blending ... [more ▼]

This work reports on the preparation of novel nanocomposite foams that are efficient broadband microwave absorbers. Carbon nanotubes are first successfully dispersed into PCL and PMMA by melt blending. Then, foaming is promoted by supercritical CO2 by depressurization. Regular cellular structures are obtained in both cases with cells size around 10-50µm. The electromagnetic interference (EMI) shielding efficiency of these materials are then evaluated and compared to the non-foamed nanocomposites. [less ▲]

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See detailSynthesis of polylactide/clay nanocomposites by in situ intercalative polymerization in supercritical carbon dioxide
Urbanczyk, Laetitia ULg; Ngoundjo, Fred; Alexandre, Michaël ULg et al

in European Polymer Journal (2009), 45(3), 643-648

Polylactide (PLA)/clay nanocomposites have been prepared by in situ ring-opening polymerization in supercritical carbon dioxide. Depending on the type of organoclay used, polylactide chains can be grafted ... [more ▼]

Polylactide (PLA)/clay nanocomposites have been prepared by in situ ring-opening polymerization in supercritical carbon dioxide. Depending on the type of organoclay used, polylactide chains can be grafted onto the clay surface, leading to an exfoliated morphology. Nanocomposites with high clay contents (30–50 wt.%), called masterbatches, have also been successfully prepared and were recovered as fine powders thanks to the unique properties of the supercritical fluid. Dilution of these masterbatches into commercial l-polylactide by melt blending has led to essentially exfoliated nanocomposites containing 3 wt.% of clay. The mechanical properties of these materials have been assessed by flexion and impact tests. Significant improvements of stiffness and toughness have been observed for the PLA/clay nanocomposites compared to the pure matrix, together with improved impact resistance. [less ▲]

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See detailSynthesis of PCL/clay masterbatches in supercritical carbon dioxide
Urbanczyk, Laetitia ULg; Calberg, Cédric ULg; Stassin, Fabrice et al

in Polymer (2008), 49(18), 3979-3986

Pre-exfoliated nanoclays were prepared through a masterbatch process using supercritical carbon dioxide as solvent and poly(epsilon-caprolactone) as organic matrix. In situ polymerization of epsilon ... [more ▼]

Pre-exfoliated nanoclays were prepared through a masterbatch process using supercritical carbon dioxide as solvent and poly(epsilon-caprolactone) as organic matrix. In situ polymerization of epsilon-caprolactone in the presence of large amount of clay was conducted to obtain these easily dispersible nanoclays, collected as a dry and fine powder after reaction. Dispersion of these pre-exfoliated nanoclays in chlorinated polyethylene was also investigated. All the results confirm the specific advantages of supercritical CO2 towards conventional solvents for filler modification. [less ▲]

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See detailPoly(caprolactone)/clay masterbatches prepared in supercritical CO2 as efficient clay delamination promoters in poly(styrene-co-acrylonitrile)
Urbanczyk, Laetitia ULg; Calberg, Cédric ULg; Benali, Samira et al

in Journal of Materials Chemistry (2008), 18(39), 4623-4630

Poly(styrene-co-acrylonitrile) (SAN)/clay nanocomposites with a high degree of clay exfoliation were prepared upon melt blending of pre-exfoliated poly(-caprolactone) (PCL)/organoclay masterbatches in a ... [more ▼]

Poly(styrene-co-acrylonitrile) (SAN)/clay nanocomposites with a high degree of clay exfoliation were prepared upon melt blending of pre-exfoliated poly(-caprolactone) (PCL)/organoclay masterbatches in a Brabender-type internal mixer. These highly filled masterbatches were synthesized by a one-pot process using supercritical carbon dioxide as a polymerization medium. During their dispersion into SAN, PCL is expected to act as a compatibilizer at the polymer–clay interface as it is miscible with the host matrix under these conditions. Reference nanocomposites based on direct melt mixing of the commercial organoclay were also prepared for the sake of comparison. The superiority of the masterbatch route in term of clay delamination efficiency has been evidenced by XRD analysis, visual and TEM observations. The effect of the nanocomposite morphology on the polymer properties was then investigated. A substantial improvement of the fire behaviour and a decrease in gas permeability have been observed for the nanocomposite containing the highest level of clay exfoliation, accompanied with a higher brittleness as evidenced by traction and impact tests. [less ▲]

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See detailSupercritical carbon dioxide, a tool for the dispersion ROP of lactone and PCL foaming: Part A
Grignard, Bruno ULg; Urbanczyk, Laetitia ULg; Stassin, Fabrice et al

Poster (2008, June 02)

Aliphatic polyesters, namely polylactide (PLA) and poly-ε-caprolactone (PCL) are biodegradable and biocompatible materials that find applications as resorbable suture (PLA) and drugs delivery vectors (PCL ... [more ▼]

Aliphatic polyesters, namely polylactide (PLA) and poly-ε-caprolactone (PCL) are biodegradable and biocompatible materials that find applications as resorbable suture (PLA) and drugs delivery vectors (PCL). Nevertheless, these polymers were mainly prepared by ring opening polymerization using aluminum alkoxide or tin alkoxide initiators in organic media. Recently, the use of supercritical carbon dioxide as polymerization medium was proposed as a potential alternative to the use toxic organic solvents. Nevertheless, due to the non-solubility of PCL in this medium, the growing chains rapidly precipitate during their synthesis leading to the formation of a bulky material that is typical of a precipitation polymerization. This work aims at investigating the dispersion ring-opening polymerization (ROP) of ε-caprolactone in the presence of fluoropolymer-based stabilizers, that were prepared by combining the ring opening polymerization of ε-caprolactone and atom transfer radical polymerization of heptadecafluorodecylacrylate (AC8) and so, stabilizing PCL micrometric particles in supercritical carbon dioxide. In practice, the ROP of CL was initiated by dibutyltin dimethoxide in the presence of PCL-b-PAC8 diblock stabilizers of differents molecular weight and composition. After 24h at 40°C, PCL was collected as a powder that consists of small-sized microspheres. Finally, post-polymerization purification of PCL (removal of tin catalyst that may lead to toxicological problems) was demonstrated to be quite feasible by supercritical fluid extraction (SFE) leading to the preparation of PCL with low catalytic residues. The second goal of this work aims at reporting on the use of sc CO2 for the preparation of foams of poly(epsilon-caprolactone) (PCL), that could be useful in the packaging sector and/or the biomedical sector as potential scaffolds for tissue engineering but also as substitutes for polystyrene thermoformed trays. The method that consists of saturating a polymer with a compressed or supercritical fluid, such as carbon dioxide followed by depressurization and polymer expansion was investigated. Indeed, no residual product is left in the foam, no toxic gas is produced and no resort to hydrocarbon solvents is required. Moreover, CO2 is cheap, non-toxic, recyclable, non-flammable and the technology of CO2-assisted foaming can be used in either a batch mode or in a continuous mode within a high-pressure extruder. [less ▲]

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See detailXRD and NMR characterization of synthetic hectorites and the corresponding surfactant-exchanged clays
Gertsmans, André; Urbanczyk, Laetitia ULg; Jérôme, Robert ULg et al

in Clay Minerals (2008), 43

Detailed reference viewed: 80 (39 ULg)