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The elaboration of new hybrid polymer/metal composite materials depends on the development of innovative polymer matrices with improved mechanical properties and high effective adhesion behaviour with metal surfaces. This way, a new type of polyolefin was developed based on a peculiar crosslinking reaction. For this elaboration, an iPP-g-MAH with 1 wt% of MAH was crosslinked with polyether triamine molecules by twin screw reactive extrusion. The evolution of the crosslinking reaction, the microstructure and the mechanical behaviour of the different materials were studied as a function of the NH2:MAH molar ratio in the range of 0:1 and 1.5:1. Gel content determination and FTIR analysis were performed to characterise the material at the molecular scale, when differential scanning calorimetry, wide angle X-rays scattering and self-successive auto-nucleation techniques were used for a deep microstructure analysis. Brillouin spectroscopy showed an interesting evolution of the elastic constants at the microscopic scale and results were in good agreement with those obtained at the macroscopic scale by a video-controlled uniaxial tensile test. Moreover, it was demonstrated that the true mechanical behaviours switch from brittle to ductile illustrating an important improvement of the resilience ability of the synthetized materials as a function of the NH2:MAH molar ratio even for molar ratio other than an equimolar ratio, with remaining MAH or NH2 chemical groups for further chemical reaction.

International audience; The gas-liquid swirl flow in a gas-liquid cylindrical cyclone separator has been characterized first qualitatively by flow visualizations. The emerged findings were then confirmed quantitatively by Laser Doppler Velocimetry measurements. The vortex core presents a very complex hydrodynamics, characterized by an alternation between a laminar and a turbulent state. The laminar regime is associated with velocities pointing in the same direction as the mean flow, while the turbulent state induces velocities in the opposite direction, i.e. a flow reversal. These observations give a first understanding of the origin of the double flow reversal regime that is encountered in swirl flows. It is shown that this flow structure appears for high swirl intensities, and results from a frequent laminarization of the vortex core. Results show that, contrary to the commonly assumed hypothesis, this flow structure is associated with good separation performance of the cyclone. Accordingly, we propose the use of multiple tangential inlets to generate the swirl motion in the cyclone, which is supposed to favor the double flow reversal regime, and thus, improve the separation efficiency.

International audience; This paper constitutes an experimental study of the separation performances of a gas-liquid cylindrical cyclone (GLCC) separator that interests the oil industry. The global hydrodynamics behavior in the GLCC is characterized by flow visualization under various inflow operating conditions. The effect of the inlet nozzle design on the performances of the separator is studied by using three different nozzles, and it proves to be a key parameter. With an insufficient nozzle restriction, low swirl intensity is imparted to the flow. Due to inadequate centrifugal effects, liquid is prematurely carried over by the gas as flooding occurs in the separator upper part. High amounts of gas are also carried under by the liquid stream. On the other hand, with a too severe nozzle convergence, the important drag applied by the gas leads to liquid "short circuiting'' the cyclone toward the gas outlet. In addition to the nozzle design, the separator performances are influenced by phenomena such as liquid bridging or the occurrence of the slug flow regime at the cyclone inlet. This paper leads to a better understanding of the links between the hydrodynamics in the GLCC and its operational limits, which is necessary to enable reliable scaling up tools.

Silane grafting and water cross-linking of polypropylene (PP) are a recent method to modify its properties, such as melt strength, heat, and chemical resistance. This work aims at grafting silanes onto PP by reactive extrusion. The occurrence of the grafting of silane onto PP was confirmed by Fourier transform infrared (FTIR) and a method based on FTIR was developed to quantify the amount of polymerized silane and that of silane grafted onto PP. The molar mass of the silane-grafted PP and its melt viscosity were also measured. A multiobjective optimization strategy was used to study the effects of processing conditions on the quality of the silane-modified PP. It was concluded that to maximize the amount of silane grafted on PP and minimize the amount of polymerized silane and the decrease in PP chain scission, screw speed and barrel temperature should be low and feed rate high. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers