Remote atmospheric pressure plasma for improving acid-base surface properties of PEEK polymer: relevance to coating adhesion

Our study focuses on a remote atmospheric pressure plasma for the improvement of polymer surface reactivity. From the perspective of linking surface modifications to adhesives performances, wettability measurements are made using two models (Owens-Wendt-Rabel-Kaelble and Van Oss-Good-Chaudhury). This study is a contribution to correlate wettability with adhesion results obtained with three-point bending test. Acid-base properties of the treated polymeric surfaces are discussed according to the Lewis’s theory

Corrosion rate determination of rare-earth Mg alloys in a Na2SO4 solution by electrochemical measurements and inductive coupled plasma-optical emission spectroscopy

The corrosion resistance of three Mg alloys containing rare-earth elements (WE43, EV31 and ZE41) was studied and compared to that of two Mg– Al alloys (AZ31 and AZ91) and of pure Mg (99.95 wt.%). Current-voltage curves and electrochemical impedance measurements were performed with rotating disk electrodes in an aerated 0.1 M Na 2 SO 4 solution. For all the alloys, it was confirmed that the intermetallic particles acted as local cathodes and that more protective films were formed on the alloys surface by comparison with the pure Mg. Corrosion rates were determined from inductive coupled plasma-optical emission spectroscopy measurements and from the electrochemical measurements. Higher corrosion rates were observed for the rare-earth Mg alloys compared to the AZ series alloys. These data allowed the corrosion mechanisms to be discussed

On the stability of the oxides film formed on a magnesium alloy containing rare-earth elements

The electrochemical behaviour of a commercial magnesium alloy containing rare-earth elements, the WE43, was investigated by electrochemical techniques in both sulphate and chloride solutions and compared to that of pure magnesium (99.95 wt %). A particular attention was paid to the oxides film that formed during the corrosion process. Electrochemical impedance data analysis allowed the oxides films thickness to be determined. The film was thinner and more protective for the WE43 Mg alloy than for the pure Mg. ToF-SIMS analysis showed the incorporation of alloying elements, mainly yttrium and zirconium in the corrosion products layer. A higher compactness due to a higher Pilling-Bedworth ratio can explain the electrochemical results

Fine-tuning of chemical and physical polymer surface modifications by atmospheric pressure post-discharge plasma and its correlation with adhesion improvement

Our study focuses on the use of a remote atmospheric pressure plasma process for the improvement of polymer surface reactivity. Indeed, surface activation of carbon-fiber-reinforced polymers that use a polyetheretherketone matrix is required to achieve strong and long-term adhesion of paint on the composite. Emphasis will be placed on the contribution of gas plasma used on surface modification. We use two techniques to characterize adherence improvement: a qualitative and industrial approach with a cross-cut test and a quantitative approach with a three-point bending test. However, to provide a better understanding of the plasma-induced modifications using air or nitrogen gas, diagnostics of the surface are also necessary. The wettability improvement, chemical surface modifications, and topography are analyzed by using contact angle measurement, X-ray photoelectron spectroscopy, and atomic force microscopy, respectively. The combination of these diagnostics highlights the capability of plasma treatment to tune the plasma/surface interactions depending on gas plasma, which results in improved adhesion

Bibliothèques d’enfer(s) : interdits, contraintes et libertés en bibliothèque

Journée thématique organisée à l\u27enssib par les élèves conservateurs promus DCB 21. La bibliothèque, espace de formation et de culture, est aussi un lieu où circulent un certain nombre d’interdits : censure, usages prohibés, restriction de certains accès. Quel rôle le bibliothécaire joue-t-il alors dans cet espace qu’il entend souvent contrôler ? Quelles formes de censure peut-il subir ou parfois faire subir ? Quels remèdes y apporter ? L’objet de cette journée fut d’interroger les pratiques afin de mieux cerner la frontière à la fois floue et fragile entre interdits et limites et de déterminer en quoi la bibliothèque peut aujourd’hui être un espace de contraintes ou de libertés

Experimental investigations of a remote atmospheric pressure plasma by electrical diagnostics and related effects on polymer composite surfaces

Surface activation of Carbon Fiber Reinforced Polymers (CFRP) using (Poly-EtherEtherKetone) (PEEK) matrices is required to achieve strong and long-term adherent painting on the composite. Among the different techniques, an industrial atmospheric pressure remote plasma has been used in this work to treat PEEK CFRP surfaces. The characterization of this device by means of electrical diagnostics related to the effect of such post-discharge on the surface modifications is discussed. Firstly, electrical characteristics of the discharge show fairly high currents associated to high voltages which suggest a nonestablished and cold arc. Power consumed by the electrical supply associated to post-discharge length and surface temperatures allowed a better understanding of the industrial device. Secondly, the effects of plasma on surface chemistry and topography are analyzed by water contact angle measurements, X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM). Investigations showed that treated surfaces exhibited better hydrophilicity mainly due to an incorporation of oxygen containing groups (up to 8.4% more) under air plasma whereas an increase of the nanoroughness and specific surface is preponderant under nitrogen plasma. Different hydrophilic capabilities of the surface obtained in air and nitrogen gas plasmas highlight a potential optimization of activation performances according to industrial specification

Table ronde "Collections et politique documentaire : la censure est-elle une fatalité ?",

Table ronde "Collections et politique documentaire : la censure est-elle une fatalité ?" lors de la journée thématique "Bibliothèques d\u27enfer(s) : interdits, contraintes et libertés en bibliothèque" organisée à l\u27enssib. Avec Bertrand CALENGE (Directeur des études, enssib) - Odile GRANDET (Directrice du projet Grand équipement documentaire du campus Condorcet) - Céline LECLAIRE (Responsable de la politique documentaire, Bibliothèque municipale de Roubaix) - Caroline RIVES (Coordinatrice de la politique documentaire à la Direction des collections, BnF). Modération assurée par Colette Gravier (Conservateur stagiaire DCB21, enssib)

Effect of post treatment on the local structure of hierarchical Beta prepared by desilication and the catalytic performance in Friedel–Crafts alkylation

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