VERGNES , Bruno

This paper presents an experimental characterization of the volume defects in polystyrene extrusion. In a first step, these defects are quantified in capillary rheometry. In a second step, a transparent slit die, fed by an extruder, is used to perform birefringence experiments and to visualize stress transients during the instability....

The flow behavior of two molten linear high-density polyethylenes (HDPE) is carefully studied using a single screw extruder equipped with a transparent slit die. Flow curves are drawn for both resins and compared. Slit die experiments are performed using birefringence technique to obtain stress fields, and image analysis is developed to...

The oscillating flow instability of a molten linear high-density polyethylene is carefully studied using a single screw extruder equipped with a transparent slit die. Experiments are performed using laser Doppler velocimetry in order to obtain the local velocities field across the entire die width. At low flow rate, the extrusion is stable and...

No description

The spurt how behavior of a linear high-density polyethylene was carefully studied in capillary experiments. Depending on the flow conditions, new types of complex transients were observed. The study pointed out a second oscillating area, described by a second hysteresis cycle, close to or inside the classical one. In one case, the second...

L'étude cinétique et rhéocinétique d'un système polyuréthane est réalisée pour déterminer les modèles théoriques les mieux adaptés, l'objectif final étant la simulation du remplissage d'un moule par injection. Le paramètre le plus important est la viscosité et son évolution avec le temps et la température. Pour un système réactif, l'évolution...

The cross-linking kinetics and the rheological behavior of a polyurethane system during curing are investigated by DSC and small amplitude oscillatory shear rheometry. In this study, isoconversional methods are applied to understand the reaction complexity. The activation energy depends on the extent of conversion. It can be shown that three...

International audience

International audience

Graphene nanoplatelets (GNP) of various sizes were mixed with polypropylene (PP) in an internal mixer to prepare composites. The effects of mixing conditions, GNP size and concentration in composites were investigated. The composites were characterized at different scales, using electron microscopy, X-ray diffraction, thermogravimetric...

International audience

Polypropylene (PP)-based nanocomposites reinforced with three different organoclays (Dellite© 67 G, Cloisite© 20, and Cloisite© 30B) were prepared via melt-mixing in an internal mixer. The three organoclays differ essentially via their organic modifier and interlamellar distance. The nanocomposites microstructure was characterized at different...

No description

In the present work, a prototype was developed to observe the flow behavior of viscous fluids (10^3 to 10^5 Pa.s) under free surface shear. The geometry of the prototype is an eccentric Couette cell where both cylinders can rotate in the same or opposite directions. Transparent windows permit in-situ observations during flow. The design,...

Abstract In the present work, a prototype was developed to observe the flow behavior of viscous fluids under free surface shear and determine an adhesion energy in this flow geometry. The geometry consists of an eccentric Couette cell (outer cylinder radius of 89.5 mm, inner cylinder radius of 43.75 mm and minimal gap of 3 mm) that can be used...

The aim of this work is to assess the potential of graphene nanoplatelets (GNP) according to their production method to improve properties of composites based on polypropylene and elaborated by melt mixing. The effects of GNP size on structural, thermal, rheological and mechanical properties of composites were investigated. Three grades of...