Traitement de surface du polycarbonate par décharge électrique pulsée basse pression (Application de la technique de mesure de la pégosité à la caractérisation du traitement)

Cette étude est dédiée à la modification de surface du Polycarbonate par un traitement plasma hors équilibre pulsé mis en œuvre dans une atmosphère d azote sous une pression de 2 mbar. Durant le pulse (le plasma est allumé ) une tension sinusoïdale de 50 kHz est appliquée entre deux électrodes planes parallèles séparées d un entrefer de 1,5 cm. Nous avons exploré les effets des différents paramètres électriques (rapport cyclique, puissance, temps de traitement ) sur les propriétés de la surface. La surface a été caractérisée par la mesure de l angle de contact mais aussi par la mesure de l arrachement d un adhésif mou déposé sur le substrat traité via un test de tack. Nous discutons les corrélations entre les résultats de chaque technique. Nous montrons qu en gardant constant le temps de traitement, la puissance et l énergie électriques il est tout de même possible d améliorer les propriétés de la surface en agissant sur la distribution temporelle de l énergie dans la décharge sans consommation supplémentaire d énergie électrique. Finalement quelques résultats de caractérisation physico-chimiques de la surface traitée sont donnés (AFM et XPS).This study is devoted to the surface modification of the polycarbonate using a non-equilibrium AC - pulsed plasma treatment in a 2 mbar-nitrogen atmosphere. During the pulse inside which the plasma is on, a 50 kHz-sinusoïdal voltage is applied between parallel plate electrodes separated by a 1,5 cm gap. We have explored the effect of different electrical parameters (duty factor, treatment time, electrical power, ) on the properties of the surface. The surface characterization is made with the well-known contact angle method and, in addition, we show that a lab-made probe-tack test, less common for this kind of experiments, can be used to analyse the surface. The links between the results of the two methods are discussed. As regards to the plasma process, it is shown that for the treatment time, the power and the energy remaining at constant values, the wettability can still be improved by acting on the temporal distribution of the energy into the discharge, i.e. without further energy consumption. Some results on the chemical characterization of the treated surfaces are given.PAU-BU Sciences (644452103) / SudocSudocFranceF

Amélioration de la mouillabilité du polycarbonate par plasma BF pulsé dans l'azote. Diagnostics par mesure de l'angle de contact

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Polystyrene thin films treatment under DC pulsed discharges conditions in oxygen

International audienceA systematic parameters study is performed in a DC pulsed glow discharge in oxygen in order to improve the wettability of thin polystyrene layers. The experimental parameters considered are the pressure P, the gas flow rate Q, the interelectrode voltage V, the frequency ν of the pulsed power supply and the treatment time tt. The wettability is characterized by the contact angle technic and evaluated by the determination of the ΔΘ/Θi = (Θl - Θf)/Θi ratio (Θl and Θf are respectively the initial and final contact angles). In the first part of the paper, the relative contact angle variations ΔΘ/Θi as a function of the treatment duration time tt are investigated. In the second part, the specific energy ε and the economical criterion γ are introduced to deduce the best running conditions through a chemical engineering approach. Taking into account the weak duty factor of the power supply (1%), it is shown that the polymer surface is treated with a minimum of energy. Finally, it is deduced that the duration time necessary to reach the same ΔΘ/Θi value is shorter for an oxygen plasma than for a nitrogen plasma

A study on the aging process of polystyrene thin films treated under DC pulsed discharges conditions in oxygen and argon-oxygen mixtures

International audienceThis paper is devoted to polystyrene thin films treatment under DC pulsed discharges in oxygen-argon mixtures. AFM analysis is used to study the surface modifications in terms of morphology and corrugation. The use of a glow post-discharge enables to disregard the degradation process in relation to the functionalization process. Thus the increase of the polystyrene wettability is mainly due to the formation of polar functions which are of great interest to a better understanding of the treatment aging. Indeed, the reorganization of the macromolecular chains after a plasma treatment enables to obtain an equilibrium state of the surface in relation to the outer environment. Polar functions orient themselves toward the polymer bulk and may interact with another one to form hydrogen bonds, which establish physical linkages within the surface and its stabilization

Numerical Simulation of Back Discharge Ignition

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