Papers by Jacques Persello
Molecules, 2019
Polytetrafluoroethylene (PTFE) is a polymer that displays exceptional properties. This synthetic ... more Polytetrafluoroethylene (PTFE) is a polymer that displays exceptional properties. This synthetic fluoropolymer is also known to crystallize very fast upon cooling. The present work highlights for the first time the influence of nanosilica clusters on PTFE crystallization at fast cooling rates (up to 5000 K·s−1). The silica was synthesized from aqueous silicate solution and the surface modification was performed using TriEthoxyFluoroSilane (TEFS). In order to understand the crystallization behavior of PTFE/silica nanocomposite at a fast cooling rate, the measurements were carried out by Fast Scanning Calorimetry (FSC). The data were consequently combined with the measurements performed by conventional Differential Scanning Calorimetry (DSC). Interestingly, the results displayed variation of the crystallization behavior for the nanocomposite at fast cooling rates compared to slow cooling rates. The differences in crystal morphologies were then observed by Scanning Electron Microscopy ...
The Journal of Physical Chemistry C, 2017
Nanocomposite materials present attractive properties and are widely employed in various applicat... more Nanocomposite materials present attractive properties and are widely employed in various applications. Most of the time, the insertion of nanoparticles in a polymer matrix induces an enhancement of its performances, yet the effect of the filler on the polymerization mechanisms and the glass transition is less often investigated. In the present study, the PFA/silica nanocomposite was studied to highlight the variation of its polymerization behavior, thermomechanical properties and glass transition induced by the presence of a clustered silica nanoparticles network. The structure of nanosilica clusters was studied by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR). The furfuryl alcohol (FA) polymerization was studied via its activation energy variation in the presence of nanosilica clusters and anhydride maleic (MA) that led to some modifications of the polymerization mechanism. An enhancement of thermal stability and an increase of glass transition temperature have been put in relief by dynamic mechanical analysis (DMA) and were correlated to the presence of silica. Finally, the activation energy associated with the glass transition highlighted a change of the polymer chain motion process in the presence of silica.
Phys. Chem. Chem. Phys., 2014
Crystallization of PDMS and PDMS silica nanocomposites was studied both from the melt and from th... more Crystallization of PDMS and PDMS silica nanocomposites was studied both from the melt and from the glassy state.
Langmuir, 2011
We present a comparison of experimentally and theoretically determined osmotic pressures for vari... more We present a comparison of experimentally and theoretically determined osmotic pressures for various colloidal dispersions. Experimental data is collected from several different silica and polystyrene dispersions. The theoretical pressure determinations are based on the Primitive Model combined with the Cell Model and the physical quantities are calculated exactly using Monte Carlo simulations in the canonical and grand canonical ensemble. The input to the simulations in terms of colloidal particle size, surface charge density etc are taken directly from experiments and the approach does not contain any adjustable parameters. The agreement between theory and experiment is excellent without any fitting parameters showing that the simplifications behind the primitive model and the cell model are physically sound. For one of the silica dispersions we have also investigated how various monovalent counterions influence the swelling properties. Within experimental errors, we are unable to detect any ion specificity, which is another support for the theoretical models used.
Pure and Applied Chemistry, 2005
Solid-liquid separation is an operation that starts with a dispersion of solid particles in a liq... more Solid-liquid separation is an operation that starts with a dispersion of solid particles in a liquid and removes some of the liquid from the particles, producing a concentrated solid paste and a clean liquid phase. It is similar to thermodynamic processes where pressure is applied to a system in order to reduce its volume. In dispersions, the resistance to this osmotic compression depends on interactions between the dispersed particles. The first part of this work deals with dispersions of repelling particles, which are either silica nanoparticles or synthetic clay platelets, dispersed in aqueous solutions. In these conditions, each particle is surrounded by an ionic layer, which repels other ionic layers. This results in a structure with strong short-range order. At high particle volume fractions, the overlap of ionic layers generates large osmotic pressures; these pressures may be calculated, through the cell model, as the cost of reducing the volume of each cell. The variation of...
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Papers by Jacques Persello