This research work deals with the effect of rare earth oxides on the PP matrix with respect to the thermal and mechanical properties and to the photo-degradation under UV irradiation exposure. The rare earth oxides are used as tracers for the identification of polymer materials, in order to have an economically efficient recycling and high speed automatic sorting of plastic wastes. The addition of 0.1 wt% of such particles of a micrometric size has a minor effect on the mechanical and thermal properties of the traced materials, as well as on the photo-degradation of the polymer after UV irradiation exposure. For 1 wt% tracer content, before UV irradiation treatment, the melting and crystallization temperatures as well as the thermal stability of the PP matrix are slightly increased, whereas the elongation at break decreases from 10 to 50% for a cross-head speed of 250 mm/min. However, the addition of 1 wt% of CeO2 improves the photo-degradation resistance of the PP matrix to UV exposure due to the UV light screening effects offered by these particles. The SEM images together with the results obtained from image processing show a homogenous dispersion of tracers in the PP matrix.This research work deals with the effect of rare earth oxides on the PP matrix with respect to the thermal and mechanical properties and to the photo-degradation under UV irradiation exposure. The rare earth oxides are used as tracers for the identification of polymer materials, in order to have an economically efficient recycling and high speed automatic sorting of plastic wastes. The addition of 0.1 wt% of such particles of a micrometric size has a minor effect on the mechanical and thermal properties of the traced materials, as well as on the photo-degradation of the polymer after UV irradiation exposure. For 1 wt% tracer content, before UV irradiation treatment, the melting and crystallization temperatures as well as the thermal stability of the PP matrix are slightly increased, whereas the elongation at break decreases from 10 to 50% for a cross-head speed of 250 mm/min. However, the addition of 1 wt% of CeO2 improves the photo-degradation resistance of the PP matrix to UV exposure due to the UV light screening effects offered by these particles. The SEM images together with the results obtained from image processing show a homogenous dispersion of tracers in the PP matrix

The rare earth oxides can be used as tracers forthe identification of polymer materials. This study focusedon the detection of these particles and their effects on themechanical and thermal properties of polypropylene (PP).A new method was carried out to increase the sortingselectivity of PP during end of life recycling process and toimprove the efficiency of sorting and its high speed identification.The tests were realized in a test system devicewhich allows the collection of static measurements of thesamples spectrum through the use of energy dispersiveX-ray fluorescence technology. Five of the seven tracerstested are clearly visible and distinguishable from thebackground sample by their Ka1 energy line at concentrationlevels of 0.1 and 0.145 wt%. For the two remainingtracers, their Ka1 energy lines come out at the same domainof energy as the source. Dispersion of rare earth oxides at0.1 and 1 wt% do not have a significant impact on thecrystallization and melting temperature as well as on thetemperature of maximum decomposition rate. The additionof 1 wt% of rare earth oxides leads to a slight increase ofthe flexural modulus, whereas the addition of 0.1 and 1wt% causes a decrease of the elongation at break. SEMimages show a homogenous dispersion of tracers in the PPmatrix.International audienceAbstract The rare earth oxides can be used as tracers forthe identification of polymer materials. This study focusedon the detection of these particles and their effects on themechanical and thermal properties of polypropylene (PP).A new method was carried out to increase the sortingselectivity of PP during end of life recycling process and toimprove the efficiency of sorting and its high speed identification.The tests were realized in a test system devicewhich allows the collection of static measurements of thesamples spectrum through the use of energy dispersiveX-ray fluorescence technology. Five of the seven tracerstested are clearly visible and distinguishable from thebackground sample by their Ka1 energy line at concentrationlevels of 0.1 and 0.145 wt%. For the two remainingtracers, their Ka1 energy lines come out at the same domainof energy as the source. Dispersion of rare earth oxides at0.1 and 1 wt% do not have a significant impact on thecrystallization and melting temperature as well as on thetemperature of maximum decomposition rate. The additionof 1 wt% of rare earth oxides leads to a slight increase ofthe flexural modulus, whereas the addition of 0.1 and 1wt% causes a decrease of the elongation at break. SEMimages show a homogenous dispersion of tracers in the PPmatrix

International audienceElectrostatic rotary bell sprayers (ERBS) are widely used in automotive painting applications. These processes involve complex airflows to shape paint sprays and transport droplets toward automotive parts to be coated. Despite the importance of shaping airflow on global spray characteristics, a detailed characterization of this aerodynamic flow is still missing. For this purpose, an experimental study was conducted on the influence of some ERBS operating parameters on the development and characteristics of shaping airflow. Results show that, for low swirl numbers, the flow behavior is close to that of annular swirling jets and a good agreement is found between ERBS flow characteristics and data available in literature. When rotational speed of the bell cup is sufficiently fast, a change of regime is observed with a shift in the longitudinal flow development and an increase of recirculation zone length. This change of regime is attributed to vortex breakdown instability, known to occur when high swirl strength is beyond a critical value. Experimental results obtained in this study put forward a clear link between the shaping air flow rate and the rotation frequency on the aerodynamics and also provide valuable leads to design shaping air flow in modern ERBS

In injection moulding or in extrusion, plastication is the step during which polymer pellets are melted by the means of mechanical dissipation provided by a rotating screw and by thermal conduction coming from a heated metallic barrel. This step is crucial for melt thermal homogeneity, charge dispersion and fibre length preservation. Although there have been a large number of theoretical and experimental studies of plastication during the past decades, mostly on extrusion and mostly using the screw extraction technique, extremely few of them have dealt with trying to visualise plastication, let alone measuring the plastication profile in real-time. As a matter of fact, designing such an equipment is an arduous task. We designed an industry-sized metallic barrel, featuring 3 optical glass windows, each window possessing 3 plane faces itself to allow for visualisation and record by synchronised cameras and lightening by lasers. The laser can be used in a laser induced fluorescence or in a particle imaging velocity measurement framework. The images recorded can be further analysed by digital image processing. Preliminary results confirm the plastication theory and show a compacted solid bed and a melt pool side by side. The total plastication length is a direct function of screw rotation frequency as it is obvious from results on the melt pool width, which increases when the screw rotation frequency decreases. However, some evidence of solid bed breakage has been recorded, whereby the solid bed does not diminish continuously along the screw but is fractured in the compression zone These experimental findings are compared to predictions by a one-dimensional model of plastication

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