Dynamic soil water repellency is an important soil phenomenon in the vadose zone as it is now recognised that most soils in the world are likely to express some degree of reduced wettability and/or long term hydrophobicity. Fractional wettability and contact angles are, however, rarely discussed or quantified for natural systems. This is particularly the case in the presence of dynamic contact angles. Soil water repellency remains a persistent impediment and challenge to accurate conceptual and numerical models of flow and storage in the vadose zone. This dissertation addresses the opportunity and pressing need for contributions that develop better quantifiable definitions, descriptions, and understanding of soil water repellency. Using materials collected from post wildfire sites, this work employs water and ethanol to identify, isolate, and quantify contact angle dynamics and fractional wettability effects during infiltration. Varied concentrations of water and ethanol solutions were applied to soils and observed through X-ray microtomography, tension infiltration experiments, and moisture content measurements in the laboratory and field. Several analyses from lab and field investigations showed that applications of ethanol and specifically, water-ethanol aqueous solutions provide unique additional insights into proportions of media that remain non-wettable and how those proportions affect overall hydrologic processes, which are not readily observable through water infiltrations alone. Observations include the wetting up of microporous structures, reduced storage, and changes in unsaturated hydraulic conductivities. Challenges which develop as a consequence of variable fluid properties including changes to operational pore assemblages, slow down of wetting fronts, and non-uniqueness relative to infiltration responses are addressed. Important insights and contributions were developed through this approach and water-ethanol mixtures are valuable tools for developing greater quantification and mechanistic data to better inform our models and understanding of dynamic soil water repellency. / Dissertation / Doctor of Philosophy (PhD) / Quantifying fluid behaviours in soils is important for a host of environmental, social, and economic reasons. Over the last 25+ years, one soil phenomenon has garnered increased attention because it interferes with our ability to carry out this work. Soils that are or become water repellent develop all over the world and where hydrophobic or non-wetting substances can enter soil and remain in pore spaces or as coatings on particles. To assist in the tracking and management of its complex effects on water storage and infiltration, the goals of this work were to develop fundamental insights into the manifestation and effects of this variable soil property on key hydrologic properties and processes. This work tests a new conceptual model for understanding these systems through both field and laboratory work and using a number of different technologies. These include X-ray microtomography (μXCT), tension infiltrometry, and more regularly applied techniques which are sensitive to changes in repellency. The works shows how combining fractional wettability and contact angle dynamics generates a stereoscopic conceptual framework which facilitates increased capacity for quantifying and understanding of soil systems expressing dynamic soil water repellency.

La génération des fréquences somme (SFG), une technique spectroscopique spécifique aux interfaces, a été utilisée pour caractériser les changements de la structure macromoléculaire du surfactant cationique chlorure de dodécyltriméthylammonium (DTAC) à l’interface silice/eau dans une plage de pH variant entre 3 et 11. Les conditions expérimentales ont été choisies pour imiter les conditions les plus communes trouvées pendant les opérations de récupération assistée du pétrole. Particulièrement, la silice a été étudiée, car elle est un des composantes des surfaces minérales des réservoirs de grès, et l’adsorption du surfactant a été étudiée avec une force ionique pertinente pour les fluides de la fracturation hydraulique. Les spectres SFG ont présenté des pics détectables avec une amplitude croissante dans la région des étirements des groupes méthylène et méthyle lorsque le pH est diminué jusqu’à 3 ou augmenté jusqu’à 11, ce qui suggère des changements de la structure des agrégats de surfactant à l’interface silice/eau à une concentration de DTAC au-delà de la concentration micellaire critique. De plus, des changements dans l’intensité SFG ont été observés pour le spectre de l’eau quand la concentration de DTAC augmente de 0,2 à 50 mM dans les conditions acide, neutre et alcaline. À pH 3, près du point de charge zéro de la surface de silice, l’excès de charge positive en raison de l’adsorption du surfactant cationique crée un champ électrostatique qui oriente les molécules d’eau à l’interface. À pH 7 et 11, ce qui sont des valeurs au-dessus du point de charge zéro de la surface de silice, le champ électrostatique négatif à l’interface silice/eau diminue par un ordre de grandeur avec l’adsorption du surfactant comme résultat de la compensation de la charge négative à la surface par la charge positive du DTAC. Les résultats SFG ont été corrélés avec des mesures de l’angle de contact et de la tension interfaciale à pH 3, 7 et 11. / Sum Frequency Generation (SFG), an interface specific spectroscopic technique, was used to characterize the changes in the macromolecular structure of the cationic surfactant dodecyltrimethylammonium chloride (DTAC) at the silica/water interface at pH values ranging from 3 to 11. The experimental conditions were selected to mimic conditions common during enhanced oil recovery operations. In particular, silica was studied since it is one of the most abundant mineral components of sandstone reservoirs, and surfactant adsorption was studied at an ionic strength (100 mM NaCl) relevant to hydraulic fracturing fluids. SFG spectra showed detectable peaks with increasing amplitude in the methylene and methyl stretching region when the pH was lowered to 3 or increased to 11, suggesting changes in the surfactant aggregate structure at the silica/water interface at a DTAC concentration above the critical micelle concentration. In addition, changes in the SFG intensity were observed for the water spectrum when increasing the DTAC concentration from 0.2 to 50 mM under acidic, neutral or alkaline conditions. At pH 3, near the point of zero charge of the silica surface, the excess positive charge due to adsorption of the cationic surfactant creates an electrostatic field that orients water molecules at the interface. At pH 7 and 11, which are above the point of zero charge of the silica surface, the negative electrostatic field at the silica/water interface decreases in magnitude with surfactant adsorption due to compensation of the negative surface charge by the positively charged DTAC. The SFG results were correlated with contact angle and interfacial tension measurements at pH 3, 7 and 11.

Dans cette étude, l’intérêt est porté sur l’effet des conditions opératoires sur l’enrobage en voie sèche de grosses particules « hôtes » par de fines particules « invitées » et aussi sur la modélisation de cet enrobage selon la méthode par éléments discrets (DEM) afin de mieux comprendre les phénomènes mis en jeu. Dans ce travail, les matériaux choisis comme particules hôtes sont les Suglets® et les particules invitées sont en stéarate de magnésium (StMg). Ces deux éléments sont introduits dans un mélangeur à fort taux de cisaillement, le Cyclomix. Les propriétés du produit final, comme la coulabilité, la mouillabilité et le degré d’avancement de l’enrobage, ont été caractérisés. La variation des propriétés est étudiée en fonction de la durée de traitement dans le Cyclomix pour diverses vitesses de rotation, taux de remplissage et rapport de taille de particules hôte et invitée. La coulabilité a été améliorée avec la durée du mélange ou la vitesse de rotationLe degré d’avancement présente une tendance semblable pour différentes conditions opératoires. Sa variation est représentée par une loi exponentielle empirique en fonction du temps de mélange, paramétrée par une constante ajustable. Cette constante permet d’estimer l’efficacité de l’enrobage. La simulation des mouvements de particules dans le mélangeur par DEM a permis d’obtenir des informations sur la position, la vitesse des particules, et d’autres paramètres énergétiques. Les champs de vitesse réelle ou numérique liés aux mouvements de particules, analysés par PIV (Particule Image Velocimetry), sont analogues. La constante d’enrobage dépend de la vitesse de rotation simulée et peut être ainsi prédite par DEM. / Investigations of the effect of the operating conditions on the dry coating and the motion of particles in a high shear mixer by the DEM simulation have been done. Big Suglets® and small Magnesium Stearate materials have been chosen for the dry coating process. The treatment has been carried out in a Cyclomix, a high shear mixer, at different mixing time, rotational speeds, filling ratio of the samples and particle size ratio to observe the effect of the operating conditions on the dry coating. A conversion ratio has been introduced to quantify the degree of coating and measured. The flowability has been improved when increasing the operation time in the mixer. Higher speeds of rotation can improve the flowability more rapidly. However, the flowability doesn’t seem to be sensitive to the filling ratio. The curves of conversion ratio versus time exhibit the same kind of variations for different operating conditions. It is possible to approximate this tendency by an exponential function in which a characteristic parameter “coating rate constant” is introduced, linked to the efficiency of the dry coating process, since the conversion ratio shows a linear relation with a flowability index and the wettability angle. Simulation of the particle motion in the mixer has been carried out by a Discrete Element Method: different parameters characterizing the location, the velocities, and the attachment of the particles have been derived. The velocity fields of the real and simulated particle motions, compared by Particle Image Velocity (PIV), are quite similar, validating the DEM method and allowing the prediction of the coating process.

Le besoin pressant de substitution du plomb dans les alliages de soudure a conduit à une introduction très rapide de nouveaux alliages sans plomb dont la connaissance en termes de comportement n'est pas assez approfondie. En effet, d'autres problématiques sont apparues (l'augmentation de la température du procédé de soudage, trop grand choix disponible dans les alliages alternatifs) alors que les problèmes relatifs aux alliages actuels sont restés sans réponse (le changement incessant de la microstructure des alliages de soudure, la méthodologie empirique prédisant la durée de vie). Tous les paramètres cités ci-dessus modifient la stabilité et la fiabilité des performances spécifiques de l'alliage de soudure et par conséquence, de tout le module électronique.De plus, avec la miniaturisation de l'électronique et les conditions d'environnement de plus en plus sévères, ces obstacles deviennent critiques et les solutions actuelles ne sont plus compatibles. Les demandes de ce marché deviennent donc de plus en plus strictes en termes de prédiction de durée de vie et de contrôle de fiabilité.L'objectif de ce projet est de comprendre et de concevoir une nouvelle formulation d'alliage sans plomb afin de développer une alternative à l'alliage plombé haute température et un alliage pour les applications haute fiabilité et en accord avec les directives gouvernementales. Des approches expérimentales avancées comme la nano-indentation, le suivi de l'évolution de la microstructure par SEM et par EDS mapping, l'étude des effets du vieillissement thermique sur la croissance de la taille des grains avec de la lumière croisée polarisée de microscopie optique etc seront utilisées pour développer un alliage sans plomb qui convienne aux exigences des applications automobile et pipeline / The urgent need for removing lead from solder alloys led to the very fast introduction of lead-free solder alloys without a deep knowledge of their behaviour. As a consequence, additional issues raised (increased thermally induced problems during soldering process, a too wide range of possible available alternative alloy formulations), while problems related to current solder alloys remained unsolved (the constant change of the solder alloy microstructure, empirical predicting lifetime methodology). All the above mentioned issues alter stability and reliability of the application specific performances of the solder alloy, and subsequently of the whole electronic module. These problems become critical and are no longer compatible, as the market goes towards miniaturization and harsh environment conditions. These market trends now require stricter life time prediction and reliability control. Objective of this project is to understand and design a novel lead-free solder formulation to develop a potential alternative to lead-based high temperature melting point solder for high reliability requirements and in accordance with governmental directives. An advanced experimental approach like nanoindentation, microstructure evolution with SEM and EDS mapping, thermal aging effects on continuous grain size growth with cross polarized light of optical microscopy etc. would be implemented to develop doped-SAC lead-free solders for the best-fit to requirements in automotives and pipelines applications

The present work related to apply hot-melt ink-jet process for imaging at offset lithographic printing form, to utilise a reusable surface for many times and particularly related to validating thermal and ultrasonic erasing processes. This dissertation investigated systematically the role of certain factors towards affecting erasing image area process on print surfaces. Thermal erasing process approved to melt and suck the image area from the surface, the results were adopted by using contact angle measurements and scanning electron microscope. Ultrasonic erasing process permitted to solve the image area by choosing erasing chemistries, influence of selected erasing chemistries on printing surface, and evaluation the process, the results were tested by UV/Vis spectrometer, contact angle, profileometery and visual microscope. / Der Fortschritt im Bereich von Charakterisierung und Verständnis für Hot-melt Ink Jet Prozesse zur Bebilderung von Offsetdruckform-Zylindern ist ein Ergebnis dieser Forschung. Die Systematik dieser Arbeit basiert auf einem theoretischen Teil, um einen geeigneten Löschprozess auszuwählen. Der Löschprozess hängt von den Eigenschaften des Hot-melt Ink Jet Materials und der genutzten Aluminiumdruckoberfläche ab. Diese werden systematisch im Labormaßstab experimentell untersucht. Der thermische Prozess wurde einerseits durch Benetzbarkeitsprüfungen und anderseites durch Rasterelektronmikroskopaufnahmen bewertet.Der Ultraschallprozess ist ein nasser Löschprozess. Die Untersuchungen wurden in vier Stufen systematisch durchgeführt - Auswahl vom geeigneten Lösungsmitteln - Einflüsse von ausgewählten Lösungsmitteln auf nicht beschichtete und beschichtete Aluminium platten - Evaluation eines Ultraschalllöschprozesses - Validation eines Löschprozesses; zur Bewertung des Löschprozesses wurden mehrere Druckplattenproben bebildert und gelöscht Die Ergebnisse wurden durch UV/Vis Spektrometer, Kontaktwinkel, Profiliometrie und Visuelle Mikroskopie getestet.

Well logs and formation testers are routinely used for detection and quantification of hydrocarbon reserves. Overbalanced drilling causes invasion of mud filtrate into permeable rocks, hence radial displacement of in-situ saturating fluids away from the wellbore. The spatial distribution of fluids in the near-wellbore region remains affected by a multitude of petrophysical and fluid factors originating from the process of mud-filtrate invasion. Consequently, depending on the type of drilling mud (e.g. water- and oil-base muds) and the influence of mud filtrate, well logs and formation-tester measurements are sensitive to a combination of in-situ (original) fluids and mud filtrate in addition to petrophysical properties of the invaded formations. This behavior can often impair the reliable assessment of hydrocarbon saturation and formation storage/mobility. The effect of mud-filtrate invasion on well logs and formation-tester measurements acquired in vertical wells has been extensively documented in the past. Much work is still needed to understand and quantify the influence of mud-filtrate invasion on well logs acquired in horizontal and deviated wells, where the spatial distribution of fluids in the near-wellbore region is not axial-symmetric in general, and can be appreciably affected by gravity segregation, permeability anisotropy, capillary pressure, and flow barriers. This dissertation develops a general algorithm to simulate the process of mud-filtrate invasion in vertical and deviated wells for drilling conditions that involve water- and oil-base mud. The algorithm is formulated in cylindrical coordinates to take advantage of the geometrical embedding imposed by the wellbore in the spatial distribution of fluids within invaded formations. In addition, the algorithm reproduces the formation of mudcake due to invasion in permeable formations and allows the simulation of pressure and fractional flow-rate measurements acquired with dual-packer and point-probe formation testers after the onset of invasion. An equation-of-state (EOS) formulation is invoked to simulate invasion with both water- and oil-base muds into rock formations saturated with water, oil, gas, or stable combinations of the three fluids. The algorithm also allows the simulation of physical dispersion, fluid miscibility, and wettability alteration. Discretized fluid flow equations are solved with an implicit pressure and explicit concentration (IMPEC) scheme. Thermodynamic equilibrium and mass balance, together with volume constraint equations govern the time-space evolution of molar and fluid-phase concentrations. Calculations of pressure-volume-temperature (PVT) properties of the hydrocarbon phase are performed with Peng-Robinson's equation of state. A full-tensor permeability formulation is implemented with mass balance equations to accurately model fluid flow behavior in horizontal and deviated wells. The simulator is rigorously and successfully verified with both analytical solutions and commercial simulators. Numerical simulations performed over a wide range of fluid and petrophysical conditions confirm the strong influence that well deviation angle can have on the spatial distribution of fluid saturation resulting from invasion, especially in the vicinity of flow barriers. Analysis on the effect of physical dispersion on the radial distribution of salt concentration shows that electrical resistivity logs could be greatly affected by salt dispersivity when the invading fluid has lower salinity than in-situ water. The effect of emulsifiers and oil-wetting agents present in oil-base mud was studied to quantify wettability alteration and changes in residual water saturation. It was found that wettability alteration releases a fraction of otherwise irreducible water during invasion and this causes electrical resistivity logs to exhibit an abnormal trend from shallow- to deep-sensing apparent resistivity. Simulation of formation-tester measurements acquired in deviated wells indicates that (i) invasion increases the pressure drop during both drawdown and buildup regimes, (ii) bed-boundary effects increase as the wellbore deviation angle increases, and (iii) a probe facing upward around the perimeter of the wellbore achieves the fastest fluid clean-up when the density of invading fluid is larger than that of in-situ fluid. / text

Sn-Pb solder has long been used in the Electronics industry. But, due to its toxic nature and environmental effects, certain restrictions are made on its use and therefore many researchers are looking to replace it. Sn-3.0Ag-0.5Cu (SAC) solders are suggested as lead-free replacements but their coarse microstructure and formation of hard and brittle Inter-Metallic Compounds (IMCs) like Ag₃Sn and Cu₆Sn₅ have limited their use in high temperature applications. In this research work, RE elements, mostly lanthanum (La), are used as potential additives to SAC alloys. They reduce the surface free energy, refine the grain size and improve the mechanical and wetting properties of SAC alloys. An extensive experimental work has been performed on the microstructure evolution, bulk mechanical properties, individual phase (matrix and IMCs) mechanical properties, creep behavior and wettability performance of the SAC and SAC-La alloys, with different (La) doping. SEM and EDS have been used to follow the continuous growth of the IMCs at 150°C and 200°C and thus provide a quantitative measure in terms of their size, spacing and volume fraction. Grain size is measured at regular intervals starting from 10 hours up to 200 hours of thermal aging using Optical Microscope with cross polarized light. Bulk mechanical properties are evaluated using tensile tests at low strain rates. Individual phase mechanical properties like Young's modulus, hardness, strain rate sensitivity index and bulge effects are characterized with nanoindentation from 100 µN up to 5000 µN loadings at different temperatures of 25°C, 45°C, 65°C and 85°C. Creep experiments are performed at elevated temperatures with good fitting of Dorn creep and back-stress creep models. Activation energy measurements are made at 40°C, 80°C and 120°C. Wettability testing on copper substrates is used for surface tension, wetting force and contact angle measurements of SAC and SAC-La doped alloys at 250°C and 260°C.

Οι πίδακες πλάσματος ατμοσφαιρικής πίεσης διαδραματίζουν ολοένα και σημαντικότερο ρόλο σε διάφορες διαδικασίες επεξεργασίας και εφαρμογής του ψυχρού πλάσματος. Αυτό συμβαίνει λόγω της ιδιαίτερης ιδιότητας τους να παράγουν ενεργά φορτισμένα σωματίδια διατηρώντας τη θερμοκρασία του αερίου σε χαμηλές τιμές. Πρόσφατα, αυτό το ελκυστικό χαρακτηριστικό οδήγησε στην εκτεταμένη χρήση τους σε εφαρμογές που απαιτούν χαμηλές θερμοκρασίες, όπως στην επεξεργασία υλικών και σε βιολογικές εφαρμογές. Η μελέτη δύο τέτοιων εφαρμογών καθώς και η ανάλυση των χαρακτηριστικών εκκένωσης που λαμβάνει χώρα στο εσωτερικό ενός αντιδραστήρα παραγωγής πίδακα πλάσματος αποτελούν τους δύο κεντρικούς άξονες αυτής της διπλωματικής εργασίας. Ένας από τους κύριους στόχους του παρόντος εκπονήματος είναι ο προσδιορισμός των βέλτιστων συνθηκών λειτουργίας ενός συστήματος παραγωγής πίδακα πλάσματος. Ως επόμενο αντικείμενο μελέτης είναι η εφαρμογή ενός δεύτερου παρόμοιου συστήματος παραγωγής πίδακα πλάσματος για τροποποίηση της επιφάνειας πολυμερούς (πολυανθρακικού) με σκοπό την αύξηση της υδροφιλίας του και βελτίωση της βιοσυμβατικότητάς του. Επιχειρείται ανάλυση των μηχανισμών που καθορίζουν την αλληλεπίδραση του πίδακα πλάσματος με το πολυμερές. Τέλος, πραγματοποιείται εφαρμογή του ίδιου συστήματος για επεξεργασία λιποσωμικών μεμβρανών ως μοντέλο βιοσυστήματος. Ειδικότερα: • Στο πρώτο κεφάλαιο αναφέρονται κάποιες βασικές έννοιες και χαρακτηριστικά που αφορούν στο ψυχρό πλάσμα με έμφαση στους πίδακες ψυχρού πλάσματος και παρατίθενται διάφορα παραδείγματα αυτών που έχουν καταγραφεί στη βιβλιογραφία μέχρι σήμερα επιλέγοντας ως κριτήριο κατάταξής τους την τάση τροφοδοσίας. • Στο δεύτερο κεφάλαιο περιγράφονται αναλυτικά οι δύο πειραματικές διατάξεις πίδακα πλάσματος ατμοσφαιρικής πίεσης όπου πραγματοποιήθηκε το σύνολο των μετρήσεων. Παρουσιάζονται τα επιμέρους όργανα που χρησιμοποιήθηκαν για τη μέτρηση συγκεκριμένων μεγεθών και ταυτόχρονα παρατίθενται φωτογραφικό υλικό. Tέλος περιγράφονται δύο εφαρμογές του δεύτερου συστήματος που αφορούν στην επεξεργασία του πολυμερούς και των λιποσωμάτων και αναλύονται οι διαγνωστικές τεχνικές που εφαρμόστηκαν. • Στο τρίτο κεφάλαιο παρουσιάζεται το σύνολο των πειραματικών αποτελεσμάτων. Για τους σκοπούς αυτής της εργασίας πραγματοποιήθηκαν ηλεκτρικές και οπτικές μετρήσεις, μετρήσεις γωνιών επαφής, XPS αναλύσεις και μετρήσεις έντασης φθορισμού. • Στο τέταρτο κεφάλαιο καταγράφονται τα συμπεράσματα που προέκυψαν από τις επιμέρους μελέτες. Σημειώνονται ενδεικτικές τιμές των παραμέτρων του πρώτου συστήματος πίδακα πλάσματος για βέλτιστη λειτουργία. Επιτυγχάνεται μείωση της γωνίας επαφής έως και 49ο και τονίζεται ο πρωταρχικός ρόλος των διεγερμένων ουδέτερων και μετασταθών σωματιδίων του πίδακα πλάσματος στην επεξεργασία. Τέλος, παρατηρείται ποσοστό διάσπασης-επεξεργασίας των λιποσωμάτων έως 15%. / Non-thermal atmospheric pressure plasma jets are playing an increasingly important role in various plasma processing applications. This is because of their practical capability to achieve enhanced gas phase chemistry without the need of elevated gas temperatures. This attractive characteristic recently led to their extensive use in applications that require low temperatures, such as material processing and biomedical applications. The studies of two applications as well as the analysis of discharge characteristics inside the atmospheric pressure plasma jet are the two principal issues of this thesis. More specifically, one of the main objects of the present thesis is the determination of the optimal operation conditions for an atmospheric plasma jet system. A second, similar atmospheric plasma jet system was applied for surface modification of a polymer (polycarbonate) by increasing its wettability Τhe analysis of mechanisms governing the interaction of plasma jet with the polymer is presented. Finally, the same system was also applied for liposomes treatment considered as biosystem model. Particularly: • In the first chapter a brief report on the general characteristics of plasma is mentioned and a review of the different atmospheric pressure plasma jets developed until today is presented. The plasma jets are classified according to their power sources. • In the second chapter the two different experimental set-ups used are described in details. The specific characteristics of each atmospheric pressure plasma jet are outlined and all the others apparatus used are presented and demonstrated by means of photography. At the end, two applications of the second plasma jet are referred concerning polymer and liposome treatment with their respective diagnostics techniques. • In the third chapter the total experimental measurements are presented. For the goals of this thesis were conducted a plenty of electrical and optical measurements, contact angles measurements, XPS analyses and fluorescence intensity measurements. • In the forth chapter all the conclusions exported of each part are recorded. Firstly, the optimal operational conditions, as excluded from the experimental procedure, are recorded. It is obtained a significant decrease of contact angle until 49ο, emphasizing on the dominant role of the reactive excited neutrals and metastables species. Also modification of the liposome membranes is observed at the percentage of 15%.

Η μείωση της ρύπανσης των μονωτήρων εξωτερικών χώρων είναι ένα αντικείμενο το οποίο έχει απασχολήσει εκτεταμένα τους μηχανικούς λόγω των απαιτήσεων που υπάρχουν στην αποδοτική λειτουργία των μονωτήρων αυτών. Στην παρούσα διπλωματική δοκιμάστηκαν τέσσερα διαφορετικά υλικά (δυο πολυμερή και δυο κεραμικά) που χρησιμοποιούνται στην κατασκευή τέτοιων μονωτήρων και μελετήθηκε η μεταβολή στην υδροφοβία της επιφάνειάς τους μετά από επεξεργασία αυτών από ψυχρό πλάσμα φθορανθράκων χαμηλής πίεσης. Παράλληλα έγιναν και ηλεκτρικές μετρήσεις σε πλάσμα Ο2 και CF4 προκειμένου να γίνουν γνωστές οι τιμές της τάσης και του ρεύματος κάτω από τις οποίες έγινε η επεξεργασία των επιφανειών. Πιο συγκεκριμένα: • Στο πρώτο κεφάλαιο έγινε μια εισαγωγή στους μονωτήρες εξωτερικών χώρων, κατάταξη αυτών με βάση τη θέση τους ως προς τους ηλεκτροφόρους αγωγούς αλλά και ως προς το υλικό κατασκευής τους. Έγινε επίσης παρουσίαση των επιπτώσεων της ρύπανσης των μονωτήρων αλλά και απαρίθμηση των μεθόδων αντιμετώπισης της. Τέλος, εξηγήθηκε η έννοια της υδροφοβίας και έγινε εισαγωγή στις ιδιότητες του πλάσματος φθορανθράκων. • Στο δεύτερο κεφάλαιο περιγράφηκε αναλυτικά η διάταξη παραγωγής πλάσματος χαμηλής πίεσης καθώς επίσης και η διάταξη μέτρησης γωνιών επαφής. Παρατίθενται φωτογραφίες αλλά και πλήρης περιγραφή όλων των επιμέρους διατάξεων που χρησιμοποιήθηκαν στην παρούσα διπλωματική εργασία. • Στο τρίτο κεφάλαιο παρουσιάστηκαν και αναλύθηκαν τα πειραματικά αποτελέσματα και μετρήσεις (ηλεκτρικές μετρήσεις και μετρήσεις γωνιών επαφής) που συλλέχθηκαν κατά την εκπόνηση της εργασία καθώς επίσης και γραφικές παραστάσεις για την ομαδοποίηση των δεδομένων. • Στο τέταρτο κεφάλαιο καταγράφηκαν τα συμπεράσματα στα οποία οδήγησε η παρούσα διπλωματική. / Reducing pollution in the surface of outdoor insulators is an issue that has occurred and has troubled lots of engineers due to strict requirements that should be met for specific insulators’ proper operation. In the present thesis, four different insulating materials (two polymerics and two ceramics) were tested and the change on their surface hydrophobic properties was studied. Furthermore, electrical measurements in O2 and CF4 plasma were taken so the values of the current and voltage under which this experiment has taken place, would be known. More specific: • In the first chapter, an introduction to outdoor insulators was made. They were classified according to their position regarding the conductors and their construction material. Also, the consequences of pollution and some ways of its control were presented. Lastly, there was explained the concept of hydrophobicity and the properties of fluorocarbon plasma. • In the second chapter, the vacuum system that was used to create low pressure, fluorocarbon plasma is analyzed as well as the device for measuring the contact angles of the samples. This detailed presentation is accompanied by photographs and full analysis of all the individual devices that were used in the present thesis. • In the third chapter, all the experimental results were presented and analyzed. The measurements (electrical and contact angles’) were plotted so that data would appear in groups. • In the forth chapter, all the conclusions of the present thesis were exported.

Made available in DSpace on 2014-12-17T14:07:03Z (GMT). No. of bitstreams: 1 ThercioHCC_TESE.pdf: 3355689 bytes, checksum: 0848bf4db8c96f8922893ef41d7b36f0 (MD5) Previous issue date: 2010-03-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This work reports the influence of the poly (ethylene terephthalate) textile and films surface modification by plasmas of O2 and mixtures (N2 + O2), on their physical and chemical properties. The plasma surface polymeric modification has been used for many researchs, because it does not affect the environment with toxic agents, the alterations remains only at nanometric layers and this technique shows expressive results. Then, due to its good acceptance, the treatment was carried out in a vacuum chamber. Some parameters remained constant during all treatment, such as: Voltage 470 V; Pressure 1,250 Mbar; Current: 0, 10 A and gas flow: 10 cm3/min, using oxygen plasma alternating the treatment time 10 to 60 min with an increase of 10 min to each subsequent treatment. Also, the samples were treated with a gas mixture (nitrogen + oxygen) which was varied only the gas composition from 0 to 100% leaving the treatment time remaining constant to all treatment (10 min). The plasma treatment was characterized in-situ with Optics Emission Spectroscopy (OES), and the samples was characterized by contact angle, surface tension, Through Capillary tests, Raman spectroscopy, Infrared attenuated total reflection (IR-ATR) and atomic force microscopy, scanning electronic Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). The results showed that oxygen treated fabrics presented high wettability, due to the hydrophilic groups incorporation onto the surface formed through spputering of carbon atoms. For the nitrogen atmosphere, there is the a film deposition of amine groups. Treatment with small oxygen concentration in the mixture with nitrogen has a higher spputered species of the samples / Neste trabalho, investigou-se a influ?ncia do tratamento superficial a plasma utilizando como gases de trabalho o oxig?nio e uma mistura de nitrog?nio + oxig?nio, sobre as propriedades f?sicas e qu?micas de tecidose filmes de Poli?ster. A modifica??o superficial de superf?cies polim?ricas por plasma tem sido bastante utilizada, pois a mesma n?o apresenta agentes nocivos ao ambiente, ?s altera??es promovidas no material s?o de escala nanom?tricas, e comprovadamente ? a t?cnica que tem apresentado resultados mais expressivos. Ent?o, tendo em vista a boa aceitabilidade do uso do plasma em materiais polim?ricos, O tratamento foi realizado em uma c?mara contendo os gases de trabalho sob baixa press?o (~ 1 mbar) mantendo-se constante durante todo ensaio alguns par?metros do plasma, tais como, voltagem: 470 V; press?o: 1,250 mbar; corrente: 0,10 A e fluxo de g?s: 10 cm3/min, usando plasma com atmosfera gasosa de oxig?nio variando-se o tempo de tratamento de 10 - 60 min com incremento de 10 min a cada tratamento subseq?ente, e tamb?m usou-se a atmosfera gasosa composta por uma mistura de nitrog?nio e oxig?nio, variando a concentra??o gasosa dos mesmos (de 0 100%), para um tempo de tratamento de 10 min. O tratamento por plasma foi caracterizado in-situ com o auxilio da Espectroscopia de Emiss?o ?tica,e as amostras foram caracterizadas por medidas de ?ngulo de contato, tens?o superficial, arraste capilar, espectroscopia Raman, Espectroscopia de infravermelho de reflex?o total atenuada (IR-ATR), e microscopia de for?a at?mica (AFM), Microscopia Eletr?nica de Varredura (MEV) e por espectroscopia de fotoel?trons excitados por raios-X (XPS). Os resultados mostraram que tecidos tratados com atmosfera de oxig?nio apresentaram elevada molhabilidade, devido a incorpora??o de grupos hidrof?licos na superf?cie formados com o arrancamento de ?tomos de carbono. Para a atmosfera de nitrog?nio, tem-se a deposi??o de um filme com base em em grupos aminas. Tratamentos com a concentra??o pequena de Oxig?nio numa mistura com Nitrog?nio tem-se maior arrancamento de esp?cies das amostras