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1
Monast, Patrick. „Wetting behavior of ternary mixtures containing surfactants“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ64410.pdf.
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2
Stables, Christa Lauren. „Wetting and Penetration Behavior of Resin/Wood Interfaces“. Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/79700.
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The goal of this project was improve the fundamental understanding of the wood-resin interaction, by looking at the relationship between the resin wetting onto wood and the resulting penetration into wood lumens. Wetting was analyzed with the sessile drop method, which observed the initial contact angle and change in contact angle over 35s. Penetration was measured within each individual tracheid. The Lucas-Washburn equation analyzed the wetting and penetration by calculating the penetration and comparing it to the measured penetration.
Wetting of four resins was compared on 3 species, to improve the understanding of adhesive wetting behavior. This study agreed with previous research, that the non-aqueous resin exhibited favorable wetting and presumably better penetration than aqueous resins, with exception of urea-formaldehyde.
Wetting and penetration of pMDI was studied on 5 wood species using the Lucas-Washburn equation. The wetting behaviors exhibited grain and species effects, which had implications on the resin availability for flake/strand-based composite products. The greater surface energy of loblolly pine most likely accounted for the significantly greater penetration of loblolly pine compared to Douglas-fir. The calculated penetration, via the Lucas-Washburn equation, exceeded the measured penetration, but it was concluded that the Lucas-Washburn equation predicted penetration reasonably well.
Wetting and penetration of phenol-formaldehyde and subsequent adhesives was compared on 3 wood species using the Lucas-Washburn equation. All contact angles were unfavorable due to a skin formation. The Lucas-Washburn equation did not predict any penetration; however, penetration was observed with all systems. The findings suggest that the system was too complex for the Lucas-Washburn equation to be able to predict accurately.Master of Science
3
Lodge, Richard. „Wetting behavior and surface potential characteristics of human hair“. The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1165335748.
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4
Tsao, Joanna W. „Influence of nanoscale roughness on wetting behavior in liquid/liquid systems“. Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53045.
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Wetting behavior of fluid/fluid/solid systems, largely influenced by surface properties and interactions between the three phases, plays a big role in nature and in industrial applications
Traditionally, wetting studies have focused on liquid/vapor systems, especially the study of a sessile liquid droplet in air. Liquid/vapor systems can only probe the effects of surface properties and interactions between the solid and the wetting liquid. This type of characterization is inadequate for liquid/liquid systems, where surface wettability is additionally influenced by interactions between the two wetting liquids.
The present study is the first to examine the effects of nanoscale roughness on wetting behavior in liquid/liquid systems and the modulation of roughness effects by fluid properties and the wetting order. This study examines both equilibrium and dynamic wetting behavior in liquid/liquid systems using well characterized substrates.
Rough substrates were fabricated by coating glass substrates with nanometer sized polymer particles. Partial dissolution of the particles and molecular de-deposition of the polymer allowed for tuning of substrate roughness while retaining the original surface chemistry. The effectiveness of this fabrication technique was verified using electron microscopy and electrokinetic analysis. We examined the wetting behavior in three fluid/fluid systems: an air/water system, a decane/water system, and an octanol/water system. The oils were chosen based on their different polarities.
Equilibrium wetting behavior was determined using contact angle measurements. Results indicate that for all systems where the primary wetting fluid was a liquid, an increase of the surface roughness resulted in Cassie-Baxter wetting. How hydrophilic a surface appears with regard to a water/fluid interface depended on the polarity of that fluid. The octanol/water system provided the strongest evidence regarding the effect of wetting order: a transition from Wenzel to Cassie-Baxter wetting was only observed when water was the primary wetting liquid. The observed transition was confirmed using a modified Wenzel/Cassie-Baxter model.
The kinetics of droplet spreading was measured using high speed optical microscopy. After a droplet was placed on a solid surface, the motion of the contact line was imaged at a rate of 1000 fps. The wetted area was then extracted using custom Matlab® scripts. The spreading kinetics underwent a transition between two regimes: a visco-inertial regime and a slower spreading regime. Results indicated that surface roughness influenced spreading kinetics in both regimes. The overall spreading rate was always slower for rough surfaces than for smoother surfaces. In liquid/liquid systems, the duration of visco-inertial regime was dependent on the surface roughness as well; in general, it was shorter for smooth substrates compared to rough substrates. Increasing the viscosity of the non-aqueous fluid significantly increased the duration of the visco-inertial regime and decreased the overall spreading rate.
This study provides insight into the competitive wetting of solid surfaces relevant in many industrial applications such as oil recovery or inkjet printing, and may guide the development of improved wetting models in an area that currently lacks an adequate theoretical description.
5
Aziz, Hossain. „COMPUTATIONAL AND EXPERIMENTAL INVESTIGATION ON THE WETTING BEHAVIOR OF DROPLET-FIBER SYSTEMS“. VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5910.
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Interaction of a liquid droplet and a fiber or layer of fibers is ubiquitous in nature and in a variety of industrial applications. It plays a crucial role in fog harvesting, coalescence filtration, membrane desalination, self-cleaning and fiber based microfluidics, among many others. This work presents a quantitative investigation on the interactions of a droplet with a fiber or layers of fibers. More precisely, the present work is focused on 1) predicting the effects of fiber’s size and material on its ability to withhold a droplet against external forces and on the liquid residue left on the fiber after the droplet detachment, 2) predicting the outcome of two fibers competing to attract the same droplet, and 3) predicting the wetting stability of a droplet deposited on a layer of electrospun fibers. This work is comprised of series of computational and experimental studies for mutual validation and/or calibration. The simulations were conducted using the Surface Evolver code and the experiments were devised using a ferrofluid and a magnet.
We also investigated the drag reduction performance of fibrous coatings because of its close connection with droplet-fiber interaction. We started by studying the drag reduction performance of a superhydrophobic granular coating because of its geometrical simplicity. We modeled the flow of water over the granular coating and studied the effects of hydrostatic pressure and microstructural properties on the drag reduction performance of the coating. We then examined the drag reduction performance of a lubricant infused surface with trapped air made of layers of parallel fibers (FLISTA). A mathematical model was developed to predict the shape of the water-lubricant interface and lubricant-air interface under a given hydrostatic pressure. This information was used to solve the flow field over the coating in a Couette configuration to find the effects of hydrostatic pressure and microstructural properties of the coating on its drag reduction performance.
6
Rosemond, St Julien Palmer III. „Characterization of the wetting behavior of place exchanged mixed-monolayer-protected gold nanoparticles“. Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/58273.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 22-24).
Mixed-monolayer-protected gold nanoparticles have been shown to have self assembling ligand shells. Given certain ligand concentrations, the NP shell can spontaneously form complex ordered domains with domain spacing as small as five angstroms. It has been proven that the solubility of NPs synthesized using a one step method is almost solely dependent on the corresponding ligand shell morphology. We have attempted to get a better understanding of the morphological differences between NPs synthesized in one step and those synthesized through place exchange by comparing their solubility characteristics. Both types NPs were functionalized using different concentrations two immiscible ligands. The place exchanged NPs almost certainly form a type of ripple shell morphology due to the presence of nonmonotonic solubility peaks in polar solvents at low hydrophilic ligand concentrations. Based on the solubility results, we conclude that the ligand shell morphology must be different for place exchanged and one step nanoparticles. The differences are most likely due to the mechanism by which place exchange populates the nanoparticles.
by St. Julien Palmer Rosemond III.
S.B.
7
Patel, Nirajkumar. „Micro scale flow behavior, fiber wetting and void formation in liquid composite molding“. The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1299253097.
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8
Nalagatla, Dinesh Reddy. „INFLUENCE OF SURFACE ROUGHNESS OF COPPER SUBSTRATE ON WETTING BEHAVIOR OF MOLTEN SOLDER ALLOYS“. UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_theses/488.
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The objective of this study is to understand the effect of surface roughness of the Cu substrate on the wetting of molten solder alloys. Eutectic Sn-Pb, pure Sn and eutectic Sn-Cu solder alloys and Cu substrates with different surface finish viz., highly polished surface, polished surface and unpolished surface were used in this work. Highly polished surface was prepared in Metallography lab, University of Kentucky while other two substrates were obtained from a vendor. Surface roughness properties of each substrate were measured using an optical profilometer. Highly polished surface was found to be of least surface roughness, while unpolished surface was the roughest. Hot-stage microscopy experiments were conducted to promote the wetting behavior of each solder on different Cu substrates. Still digital images extracted from the movies of spreading recorded during hot-stage experiments were analyzed and data was used to generate the plots of relative area of spread of solder versus time. The study of plots showed that surface roughness of the Cu substrate had major influence on spreading characteristics of eutectic Sn-Pb solder alloy. Solder showed better spreading on the Cu substrate with least surface roughness than the substrates with more roughness. No significant influence of surface roughness was observed on the wetting behavior of lead free solders (pure Sn and eutectic Sn-Cu).
9
Smyth, Katherine Marie. „Wetting hysteresis and droplet roll off behavior on superhydrophobic surfaces by Katherine Marie Smyth“. Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59918.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 55-56).
Various states of hydrophobic wetting and hysteresis are observed when water droplets are deposited on micro-post surfaces of different post densities. Hysteresis is commonly defined as the difference between the advancing and receding contact angle and after many decades of research, the mechanisms governing hysteresis are still not fully understood. Particularly, stick-slip behavior of the three-phase contact line has been observed and qualitatively attributed to surface or chemical heterogeneities, but the behavior has yet to be quantified. In this thesis, contact line motion particularly focused on stick-slip behavior and its influence on drop width and contact angle was examined as a new approach to understanding hysteresis as pertaining to micro-textured surfaces. This work focuses on developing a fundamental understanding and physical model of the stick-slip behavior of the contact line and preliminarily explores the influence of contact line velocity on this stick-slip behavior and contact angle. By characterizing stick-slip behavior and hysteresis on micro-post surfaces, models can be developed that in the future can aid in surface design for optimal wetting behavior in industrial and power plant applications. Additionally, the pinning parameter has been used to predict roll off angle on micro-post surfaces for a variety of post densities and these predictions have been experimentally verified. With further definition of the pinning parameter to include surface roughness and impact phenomena, the pinning parameter can be used in surface design for droplet shedding in industrial applications.
S.B.
10
Denham, Martha H. „The Use of Laboratory Testing to Understand the Behavior of Collapsible Soil Upon Wetting“. PDXScholar, 1992. https://pdxscholar.library.pdx.edu/open_access_etds/4664.
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In developing a constitutive model that could predict the settlement due to the collapse, several goals needed to be met. These were to gain an understanding of the collapse phenomenon, knowing the soil properties at the natural water content and how they change after collapse, and develop and test the new model. It was felt that laboratory testing could be of use. The types of test conducted included use of the Oedometer, Pressuremeter, and Triaxial tests. The material that was used for the testing was a "generic" soil manufactured out of diatomite. In all of the tests the soil was tested dry and saturated in order to establish state limits of the soil. Next, the soil was loaded dry then inundated which initiated the collapse of the soil. The stress and strains were continually recorded. From the testing it was concluded that there is a stress-strain region where after collapse the soil looses considerable strength. With increasing stress and strain the soil eventually becomes stronger. From the triaxial tests, the stress-strain data from this "region of collapse" was used in a constitutive model. Stress paths from the Oedometer and Pressuremeter tests were then successfully applied to the model. The constitutive model used was an elasto plastic model. The elastic and plastic strain components were provided using functions for yielding, hardening, plastic potential, and failure as proposed by Paul Lade in his work on cohesionless, frictional materials. Results from the conventional triaxial shear tests and isotropic compression tests were used to derive the values of the functions for the model. The end result was three dimensional surfaces for failure, yielding, plastic work and plastic potential for the dry and saturated soil in the zone of collapse.
11
Attinger, Daniel. „An investigation of microdroplet surface deposition : transient behavior, wetting angle dynamics and substrate melting phenomenon /“. Zürich : [s.n.], 2001. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=14004.
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12
Worbs, Peter. „Wetting behavior of titanium carbide films for carbon-copper braze joints in high heat flux components“. kostenfrei, 2009. http://mediatum2.ub.tum.de/node?id=823480.
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13
Sadeghpour, Nima. „The Influence of Surface Roughness and Its Geometry on Dynamic Behavior of Water Droplets“. Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700094/.
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In this study the author reports the effects of surface roughness on dynamic behavior of water droplets on different types of rough structures. First, the influence of roughness geometry on the Wenzel/ Cassie-Baxter transition of water droplets on one-tier (solid substrates with Si micropillars) surfaces is studied (Chapter 3). In order to address distinct wetting behaviors of the advancing and receding motions, the author investigates the Wenzel/ Cassie-Baxter transition of water droplets on one-tier surfaces over a wide range of contact line velocities and droplet volumes in both advancing and receding movements. The discussions are strengthened by experimental results. According to the author’s analysis, the advancing contact zone tends to follow the Cassie-Baxter behavior for a wider range of geometric ratios than the receding contact zone. Physical phenomena such as advancing contact line rolling mechanism and the pinning of the receding contact line are introduced to justify distinct transition points of the advancing and receding movements respectively. Based on the analysis provided in Chapter 3, the author experimentally investigates the contact line fluctuations and contact line friction coefficients of water droplets on smooth, one-tier, and two-tier (with carbon nanotubes (CNTs) grown on Si micropillars) surfaces in Chapters 4 and 5. Both the advancing and receding contact line fluctuations/friction coefficients have been measured, analyzed and compared on smooth, one-tier, and two-tier surfaces over a wide range of contact line velocities and droplet volumes. A comprehensive analysis is provided to explain the experimental observations.
14
Annavarapu, Rama Kishore. „Elastocapillary Behavior and Wettability Control in Nanoporous Microstructures“. University of Toledo / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1544705326035201.
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15
Grimmer, Philipp E. S. [Verfasser], und Thomas [Akademischer Betreuer] Hirth. „Wetting, de-icing and anti-icing behavior of microstructured and plasma-coated polyurethane films / Philipp E. S. Grimmer ; Betreuer: Thomas Hirth“. Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2019. http://d-nb.info/1181099285/34.
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16
Larson, Hans Christian. „Replacement Rates of Initially Hydrocarbon-Filled Microscopic Cavities with Water“. BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7496.
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Wetting behaviors influence many aspects of life and industry from consumer product goods to oil recovery to cosmetics. While the traditional solid-liquid-vapor (SLV) system has been studied for many years now, wetting transitions in the solid-liquid-liquid (SLL) system has remained relatively unexplored. The purpose of this work is to bring light to the wetting transition of the solid-liquid-liquid system and to understand the replacement rates of initially hydrocarbon-filled microscopic cavities with water and the factors affecting these rates. Factors studied were viscosity, density, diffusion related properties, and surface related properties in both hydrocarbon-saturated and hydrocarbon-non-saturated conditions. Cylindrical microscopic cavities were etched in a silicon wafer, filled with various organic solvents dyed with fluorophores, then submerged in water. Through fluorescence microscopy techniques, the transition or replacement rates of the initially hydrocarbon-filled cavities with water in both hydrocarbon-saturated and hydrocarbon-absent water conditions are observed. Among the factors we investigated, namely viscosity, density, surface chemistry, and diffusive flux (composed of solubility and diffusivity), diffuse flux dominated replacement rates in hydrocarbon-absent water conditions. By using hydrocarbon-saturated water, diffusive flux was minimized, allowing for deeper investigation of other factors. In the hydrocarbon-saturated scenario, replacement rates are largely affected by initial fluid motion, specific cavity geometry, and cavity penetration mechanisms. Image analysis reveals the geometry of the oils in the cavities and shows how the transition from hydrocarbon-fully-filled to hydrocarbon-partially-filled states occurs in the SLL system.
17
Rose, Lesley Anne. „Wetting behavior of Fe-Ni-Co-Cu-O-S melts against olivine and chromite as a function of melt composition, oxygen fugacity, and pressure“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0018/MQ53464.pdf.
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Brunson, Kennard Marcellus. „Synthesis and Characterization of methylene bis (p-cyclohexyl isocyanate)-poly (tetramethyl oxide) based Polyurethane Elastomers“. VCU Scholars Compass, 2005. http://scholarscompass.vcu.edu/etd/1211.
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This research concerns the development and characterization of methylene bis (p-cyclohexyl isocyanate/butanediol) (HMDI/BD) based polyurethanes used in connection with surface-active anti-microbial polyurethanes. Previously studied polyurethanes having an isophorone diisocyanate/butanediol (IPDI/BD) hard block contaminated water during dynamic contact angle (DCA) analyses. This contamination by unknown species confounds results from biocidal studies and jeopardizes the use of the polyurethane as a matrix polyurethane. By contrast, polyurethanes with methylene bis (p-cyclohexyl isocyanate)/butanediol hard block showed no contamination during DCA analysis. For this reason, further study of HMDI/BD/PTMO polyurethanes was conducted. HMDI/BD polyurethanes were synthesized with 15-50wt% hard block and a soft block of PTMO-2000 or PTMO-1000 where PTMO-2000 is poly (tetramethylene oxide) with a molecular weight of 2000g/mol and PTMO-1000 has a molecular weight of 1000g/mol. Characterization was performed with FT-IR and 1H NMR spectroscopy to verify polyurethane composition as well as hard block percentage. Thermal characterization was performed with modulated differential scanning calorimetry (MDSC). From MDSC, the glass transition temperatures of the soft and hard block for polyurethanes with PTMO-2000 as the soft block were -80°C and 86°C, respectively. For corresponding polyurethanes containing PTMO-1000 as the soft block, the measured Tgs for the soft and hard segments were -55°C and 65°C, respectively. The disparity between the respective soft and hard segment Tgs of these polyurethanes of differing soft block molecular weights is due to increased phase mixing that causes an increase in soft block Tg and a decrease in hard block Tg for the PTMO-1000 polyurethanes. From dynamic contact angle analyses of HMDI/BD/PTMO polyurethanes, the advancing and receding contact angles gradually decreased with each cycle but approached 80° and 60°, respectively. Results from force-distance curves with flamed glass slides obtained before and after immersion of the polyurethane coatings indicated that no water contamination occurred. Tensile tests demonstrated that hard block percentage, soft block molecular weight, and the amount of chain extender influences mechanical properties. For example, increasing hard block weight percentage increases the modulus. HMDI/BD(30)/PTMO-2000 (PU-1), HMDI/BD(25)/PTMO-2000, (PU-2) and HMDI/BD(35)/PTMO-2000 (PU-10) exhibited the best elastomeric properties. As the final outcome, lack of contamination and good mechanical properties made PU-2 and PU-9 (HMDI/BD(50)/PTMO-1000) suitable candidates as polyurethane matrices for polymer surface modifier evaluation.
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Setu, Siti Aminah. „Interfacial instabilities and wetting behaviour in confinement“. Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:7848f713-437b-4be8-b5f8-8232fcd59667.
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Interfacial instabilities and wetting phenomena of phase separated colloid-polymer mixtures are addressed in this study. Colloidal particles offer certain advantages over molecular systems, due to their larger lengthscales and slower timescales. Moreover, the phenomena can be directly visualised using laser scanning confocal microscopy, and a perfect match with soft-lithography fabrication techniques can be exploited. In particular, we study the viscous fingering instability in three dimensions, focusing on the role of wetting conditions and of thermal fluctuations. Combined with results obtained by lattice Boltzmann simulations, we reveal that the cross-over of the meniscus in the direction across the channel thickness is controlled by the capillary and Peclet numbers, and viscosity contrast of the system. The curvature of the meniscus has a pronounced effect on the onset of the Saffman-Taylor instability, in which the formation of the viscous fingers is suppressed up to a certain threshold. Furthermore, we investigate a related contact line instability, which leads to entrainment and subsequent droplet pinch-off. A theoretical prediction for the onset of the instability is developed, which shows a good agreement with the experimental observations and yields a method to directly measure the slip length of the interface. The large thermal fluctuations of our interface play an important role in pinch-off events, leading to periodic emission of droplets of similar sizes. Finally, we study wetting phenomena at geometrically sculpted walls. We focus on the shape, the thickness and the radius of curvature of the adsorbed liquid film, and find good agreement with theory. Changing the curvature of the wedge from a flat surface to a capil- lary slit furthermore smoothly connects wetting behaviour and capillary condensation, again in qualitative agreement with theory. Non-equilibrium effects may interfere with the data and are difficult to rule out. We end with recommendations for future work.
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Razak, Huzaifah Haritsah Abdul. „Wetting behaviour of colloid-polymer mixtures in confinement“. Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:e75a8463-fe02-46f3-ba95-7d7b40c955cb.
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We study the wetting behaviour of phase-separating colloid-polymer mixtures in confinement. The phase separation is due to the depletion attraction between the colloids mediated by the polymers and bears similarities to ordinary phase separation of oil and water. We use laser scanning confocal microscopy to investigate the behaviour of our colloidal mixture in the vicinity of different substrates, which serve as the confining walls. The glass walls used are chemically modified with two types of polymer, polyacrylamide and chitosan, and we also use clean glass as a reference. We find that the polymer grafting of the surfaces has a pronounced effect on the wetting behaviour. Here, we observe the formation of colloidal liquid droplets, which implies that the coated walls are partially wet. This geometry allows for the determination of the contact angle. The shape of the droplet is theoretically described by the interplay between gravity and interfacial curvature, with the contact angle entering as a boundary condition. The reconstructed interfacial drop profiles are then fitted to the theoretical model to quantitatively study its variation as a function of colloid-polymer state point, properties of the confining wall, and droplet size. We also visually observe Cahn's wetting transition from partial to complete wetting in three series of state points as we move closer to the binodal. This enables us to estimate the wetting transition line in our phase diagram. In addition, we disperse polyacrylamide-coated silica beads into our colloid-polymer mixtures to observe the wetting effects near curved surfaces. We generate theoretical plots based on the conditions of mechanical equilibrium, and compare to the experiments. Our studies shine light on partial wetting phenomena for systems where the interfacial roughness is comparable to the other relevant lengthscales in the system, such as the droplet size or the curvature of the surface.
21
David, Samuel. „Investigation of the Wetting Behaviour of Evaporating Drops“. Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/12174.
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Knauf, Jan [Verfasser], Alexander [Akademischer Betreuer] Böker, Karsten [Akademischer Betreuer] Reihs, Alexander [Gutachter] Böker, Karsten [Gutachter] Reihs und Hans-Jürgen [Gutachter] Butt. „Synthesis of highly fluorinated precursors and their deposition conditions for self-assembled monolayers with defined small-scale surface structures as templates for the manipulation of wetting behavior / Jan Knauf ; Gutachter: Alexander Böker, Karsten Reihs, Hans-Jürgen Butt ; Alexander Böker, Karsten Reihs“. Potsdam : Universität Potsdam, 2020. http://d-nb.info/1219662925/34.
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Wijeratne, Susil. „Liquid drop flow behaviour in unsaturated non-wetting packed beds /“. [St. Lucia, Qld.], 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16336.pdf.
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Frenzel, Ralf, Christa Blank, Karina Grundke, Veneta Hein, Bernd Schmidt, Frank Simon, Michael Thieme und Hartmut Worch. „Wettability of Methacrylate Copolymer Films Deposited on Anodically Oxidized and Roughened Aluminium Surfaces“. Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-107056.
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The wetting behavior of water on methacrylate copolymer films was studied on anodically oxidized and micro-roughened aluminium surfaces and also on smooth model surfaces. The copolymerization of tert-butyl methacrylate with a methacrylate containing a fluoroorganic side chain led to a considerable decrease of the surface free energy, but not to a superhydrophobic behavior of polymer-coated, micro-roughened aluminium surfaces. However, copolymers containing both hydrophobic and hydrophilic sequences are able to form superhydrophobic films. X-ray photoelectron spectroscopy showed that an enrichment of the interface between the solid phase and the air by fluorine-containing polymer components was the reason for the strong decrease of the surface free energy. The hydrophilic segments of the copolymers improved the ability to wet the highly polar aluminium surface and to form films of higher density.
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Crichton, Donna. „The interaction of oils with surfactant monolayers at the air-water surface“. Thesis, University of Hull, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310247.
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Stark, Alyssa Yeager. „The Effect of Water on the Gecko Adhesive System“. University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1405334677.
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Frenzel, Ralf, Christa Blank, Karina Grundke, Veneta Hein, Bernd Schmidt, Frank Simon, Michael Thieme und Hartmut Worch. „Wettability of Methacrylate Copolymer Films Deposited on Anodically Oxidized and Roughened Aluminium Surfaces“. Technische Universität Dresden, 2009. https://tud.qucosa.de/id/qucosa%3A26713.
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The wetting behavior of water on methacrylate copolymer films was studied on anodically oxidized and micro-roughened aluminium surfaces and also on smooth model surfaces. The copolymerization of tert-butyl methacrylate with a methacrylate containing a fluoroorganic side chain led to a considerable decrease of the surface free energy, but not to a superhydrophobic behavior of polymer-coated, micro-roughened aluminium surfaces. However, copolymers containing both hydrophobic and hydrophilic sequences are able to form superhydrophobic films. X-ray photoelectron spectroscopy showed that an enrichment of the interface between the solid phase and the air by fluorine-containing polymer components was the reason for the strong decrease of the surface free energy. The hydrophilic segments of the copolymers improved the ability to wet the highly polar aluminium surface and to form films of higher density.
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Leboeuf, Sébastien. „Dynamic wetting and heat transfer behaviour of aluminium droplets impinging and solidifying on copper substrates“. Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=81548.
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The present work describes an experimental set-up built to simulate dynamic wetting and heat transfer occurring in many rapid solidification processes. Tests were performed with molten aluminium droplets falling from a crucible onto a metallic substrate. A high-speed camera captured the evolution of the droplet's geometry, while thermocouples, inserted inside the metallic substrate, allowed a heat transfer analysis to be performed. Aluminium 5754 was found to have a better initial dynamic wetting and heat transfer compared to pure aluminium. An increase in the initial temperature of the substrate was associated with better dynamic wetting and heat transfer. The heat flux was also increased by the use of a polished substrate compared to a sand-blasted substrate. The use of helium increased the two aspects studied compared to air and argon atmosphere. Totally non-wetting conditions were found for droplets in an argon atmosphere with less than 0.02% O2.
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Germanà, Sarah. „HLAS reactive binder in detergent granulation : relationship between phase behaviour and wetting and adhesive properties“. Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/19792/.
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The main aim of the work reported in this thesis is to gather experimental evidence of the relationship between HLAS (Linear Alkylbenzene Sulphonic Acid) phase changes and binding performance in detergent granulation. In order to fulfil this goal a novel micromechanistic apparatus, the EC-MFB (Environmentally Controlled Micro Force Balance), capable of characterising binder-particle interactions, such as contact angles and liquid bridge adhesive forces, in an environmentally controlled glove box, has been designed developed and commissioned. Linear alkylbenzene sulphonic acid (LAS acid or HLAS) is a reactive binder used in industrial detergent granulation processes. The neutralisation of HLAS with sodium carbonate particles during granulation generates Sodium Linear Alklybenzine Sulphonate (LAS-Na), one of the world’s most used anionic surfactants for washing powder formulations. The reaction neutralises HLAS to increasing degrees, depending on the amount of acid reacted to form the salt. During granulation the binder has the dual function of forming physical links between the particles and participating in the neutralisation reaction to form LAS-Na. Both HLAS and LAS-Na have been found to be highly hygroscopic. The experimental investigation described here is aimed at establishing whether the extent of HLAS neutralisation and the binder water content influences the wettability and adhesive strength of individual liquid bridges holding particles together during the granulation process. HLAS being a reactive binder , the characterisation of the wetting and adhesive behaviour is complicated by their strong dependency on the kinetics of the binder-powder reaction. Hence, a novel approach to reactive binder studies is presented here, with the experiments carried out using inert particles and acid that has been partially pre-neutralised with Na2CO3. Contact angle and spreading velocity measurements show that the higher the degree of neutralisation the lower is the tendency of the liquid to wet the particles. Moreover, it will be shown that particle wetting is strongly dependent on binder water content and relatively humidity (RH). A “sticky regime map” is presented as a function of neutralisation and water content distinguish between wetting and non-wetting conditions. This highlights the importance of controlling the environmental conditions, both during the granulation process and the storage of the product materials.
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Klinter, Andreas. „Wetting behaviour of aluminum alloys on ceramic substrates and its effect on the stability of aluminum foams“. Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:8881/R/?func=dbin-jump-full&object_id=92344.
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Villa, Stefano. „Behaviour of a Colloid close to an Air-Water Interface : Interactions and Dynamics“. Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS074/document.
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Malgré un rôle important en physique, biologie et dans les processus industriels tels l’agroalimentaire et la dépollution de l’eau, la dynamique d'une particule colloïdale à proximité d'une interface fluide et ses interactions avec l’interface sont des phénomènes physiques encore débattus.Dans cette thèse, nous explorons la dynamique et l'interaction de particules colloïdales individuelles à proximité d'une interface air-eau à l’équilibre thermique.Afin de mener cette étude sans perturber le système expérimental, nous avons conçu et construit un microscope interférentiel à double onde adapté à l'interface air-eau. Contrairement à d'autres techniques expérimentales, notre configuration permet la mesure précise de la distance absolue entre particule l'interface sans nécessiter d’étalonnage ou d’hypothèse sur l'emplacement de l'interface. Nous avons ainsi pu obtenir des trajectoires hautement résolues de particules en 3D proches de l'interface, permettant la mesure précise des diffusions proche de l’interface et des interactions particules-interface.Le système montre deux profils d’énergie potentielle différents. Deux distances d’équilibre particule-interface sont ainsi observées. La plus grande peut être expliquée par la compétition des interactions de Van der Waals et électrostatiques avec la pesanteur. La distance d’équilibre plus courte ne peut s’expliquer que par la présence d’une interaction attractive supplémentaire. Les origines possibles de cette interaction sont discutées.En utilisant une nouvelle méthode d'analyse des déplacements quadratiques moyens des particules dans un potentiel générique, nous avons pu accéder aux coefficients de friction visqueuse des particules en fonction de la distance à l'interface. De manière singulière, l’interface air-eau se comporte comme une paroi liquide pour le mouvement des particules parallèlement à l’interface et comme une paroi solide pour le mouvement des particules perpendiculaire à l’interface. Ce résultat expérimental peut être partiellement rationalisé en considérant des modèles récents basés sur l’incompressibilité de surface. Cependant, certaines différences entre les expériences et les théories demeurent. Les coefficients de friction visqueuse sont plus importants que les prédictions hydrodynamiques et dépendent de la charge électrique des particules, ce qui suggère un possible rôle des phénomènes électrocinétiques.Enfin, le piégeage des particules à l'interface air-eau et leur angle de contact ont été mesurés tout en modifiant la force ionique de la solution aqueuse et en faisant varier l‘état de surface des colloïdesDespite the relevance to environmental, biological and industrial processes, the motion of a colloidal particle close to a fluid interface and the way it interacts with the water surface are still largely elusive and intriguing physical phenomena.In this thesis, we explore the motion dynamics and the interaction of individual colloidal particles close to an air-water interface in thermal equilibrium.In order to investigate them without perturbing or altering the experimental system, we designed and built a dual-wave reflection interference microscope working with an air-water interface geometry. Contrary to other established experimental techniques, our set-up allows accurate measurements of the absolute particle-interface distance and thus does not require any calibration or assumption to know the location of the interface. Highly resolved 3D particle trajectories close to the interface were obtained, from which information on particle diffusion close to the interface and particle-interface interactions are obtained.The system shows two different potential energy landscapes resulting in two different equilibrium particle-interface distances. The larger one can be fairly explained by Van der Waals and electrostatic interactions combined with gravity. The shorter one highlights the existence of an unexpected additional attractive interaction. The possible origins of such an interaction are discussed.Using a method of analysis of the particle mean square displacements in a generic potential we developed, we were able to access to particle drag coefficients as a function of the distance from the interface. Peculiarly, the air-water interface acts as a slip boundary for the particle motion parallel to the interface and as a no-slip boundary for the particle motion perpendicular to the interface. This experimental result can be partially rationalized considering recent models based on surface incompressibility. However, some discrepancies between experiments and theories remain. Experimental drag coefficients are larger than the hydrodynamic predictions and depend on the particle electrical charge, pointing therefore to a possible role of electrokinetic phenomena.Finally, the particle trapping at the air-water interface and its contact angle were observed while tuning the ionic strength of the aqueous solution and varying the surface state of the colloids
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Postill, Harry E. „Weather-driven clay cut slope behaviour in a changing climate“. Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/35832.
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Long linear earthwork assets constructed in high-plasticity overconsolidated clay are known to be deteriorating due to long-term effects of wetting and drying stress cycles as a result of seasonal weather patterns. These stress cycles can lead to shallow first-time failures due to the mobilisation of post-peak strength and progressive failure. Design requirements of new earthworks and management of existing assets requires improved understanding of this critical mechanism; seasonal ratcheting. Incremental model development and validation to allow investigation of multiple inter-related strength deterioration mechanisms of cut slope behaviour in high-plasticity overconsolidated clay slopes has been presented. Initially, the mechanism of seasonal ratcheting has been considered independently and a numerical modelling approach considering unsaturated behaviour has been validated against physical modelling data. Using the validated model, the effects of slope geometry, design parameter selection and design life have been considered. Following this, an approach to allow undrained unloading of soil, stress relief, excess pore water pressure dissipation, seasonal ratcheting and progressive failure with wetting and drying boundary conditions has been considered. Hydrogeological property deterioration and the potential implications of climate change have been explored using the model. In both cases the serviceable life of cut slopes is shown to reduce significantly in the numerical analyses. Finally, a model capable of capturing hydrogeological behaviour of a real cut slope in London Clay has been developed and validated against long-term field monitored data. Using the validated model, a climate change impact assessment for the case study slope has been performed. The numerical analyses performed have indicated that seasonal ratcheting can explain shallow first-time failures in high-plasticity overconsolidated clay slopes and that the rate of deterioration of such assets will accelerate if current climate change projections are representative of future weather.
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Kemppainen, K. (Kalle). „Towards simplified deinking systems:a study of the effects of ageing, pre-wetting and alternative pulping strategy on ink behaviour in pulping“. Doctoral thesis, Oulun yliopisto, 2014. http://urn.fi/urn:isbn:9789526203805.
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Abstract The aim of the deinking process is to produce deinked pulp from recovered papers (RCPs) with sufficient brightness and cleanliness to fulfil the quality requirements set by the paper grade to be produced. Due to the excessive production costs and material losses of modern deinking processes, there is a need to simplify deinking lines. A prerequisite for this action is that ink content bound to fibres, dirt content and ink fragmentation are minimised in the pulping stage. Thus, it is important to recognise the factors affecting ink behaviour in pulping, to search for new ways to improve ink detachment from RCPs in pulping and to search pulping methods that could efficiently process RCPs printed with various inks. The aim of this thesis was to obtain new information on how the environmental conditions that prevail during the storage and transportation of RCPs affect ink behaviour in subsequent pulping and to find out whether there is further potential to decrease ink content bound to fibres, not only by treating recovered papers chemically before the actual pulping process, but also by removing the detached ink particles during the pulping process. The results show that if some RCPs are very moist and exposed to high temperatures for a reasonable time before the pulping process, the problems in releasing ink from the fibres in pulping become more pronounced and the pulp is dirtier compared to pulp from RCPs that are thermally aged but dry. Properly wetting some RCPs with conventional alkaline deinking chemicals in suitable conditions ahead of the pulping process reduces the ink content that remains bound to the fibres after the pulping process. The efficiency of the pre-wetting treatment in aiding ink detachment from fibres in subsequent pulping is highly dependent on the alkalinity, temperature and duration of the treatment. Semi-continuous ink removal during the pulping process offers the possibility to continue defibering, ink detachment from fibres and dirt fragmentation in pulping without fear of ink redeposition into or onto the fibres, thus resulting in fully disintegrated pulp with lower ink content bound to fibres than in conventional pulping. This enables efficiently simultaneous processing of, for example, papers printed with water-based inks and tonersTiivistelmä Siistausprosessin tavoitteena on tuottaa keräyspapereista valmistettua vaaleaa ja puhdasta massaa, jota voidaan käyttää uusien paperituotteiden valmistamiseen. Siistausprosesseja pyritään yksinkertaistamaan nykyisten monimutkaisten prosessien korkeiden tuotantokustannusten ja materiaalitappioiden vuoksi. Eräs edellytys siistausprosessien yksinkertaistamiselle on, että kuiduissa kiinni olevan musteen pitoisuus, massan likapitoisuus ja musteen liiallinen pilkkoutuminen minimoidaan siistausprosessin ensimmäisessä vaiheessa, pulpperoinnissa. Täten on tärkeää tunnistaa musteen käyttäytymiseen pulpperoinnissa vaikuttavat tekijät, etsiä uusia mahdollisuuksia parantaa musteen irrotusta keräyspapereista sekä kehittää pulpperointimenetelmiä, joilla voitaisiin prosessoida tehokkaasti eri painomenetelmillä painettuja papereita. Tämän työn tavoitteena oli saada uutta tietoa siitä miten ympäristöolosuhteet, joille keräyspaperit voivat altistua varastoinnin ja kuljetuksen aikana, vaikuttavat musteen käyttäytymiseen pulpperoinnissa. Lisäksi tavoitteena oli selvittää voitaisiinko kuituihin kiinni jääneen musteen pitoisuutta vähentää esiliottamalla keräyspapereita sopivissa kemiallisissa olosuhteissa ennen pulpperointia ja poistamalla irronneet mustepartikkelit massan seasta pulpperoinnin aikana. Tulokset osoittavat, että jos tietyt keräyspaperit ovat erittäin kosteita ja altistuvat korkealle lämpötilalle riittävän pitkän ajan ennen pulpperointia, tulee musteen irrottaminen kuiduista pulpperoinnissa vaikeammaksi ja tuotettu massa likaisemmaksi, kuin sellaisista keräyspapereista, jotka ovat altistuneet kuivina korkealle lämpötilalle. Kuituihin kiinnittyneen musteen pitoisuutta voidaan vähentää esiliottamalla tiettyjä keräyspapereita alkalisilla siistauskemikaaleilla sopivissa olosuhteissa ennen pulpperointia. Esiliotuksen kyky parantaa musteen irrotusta kuiduista pulpperoinnissa riippuu voimakkaasti esiliotusvaiheen alkalisuudesta, lämpötilasta ja kestosta. Kun irronneet mikroskooppiset mustepartikkelit poistetaan massasta useassa vaiheessa pulpperoinnin aikana, voidaan paperin kuidutusta, musteen irrottamista kuiduista ja likapilkkujen hajottamista jatkaa ilman että haitallista musteen takaisin kiinnittymistä kuituihin tapahtuu. Tämä mahdollistaa esimerkiksi vesipohjaisten musteiden ja lasertulosteiden samanaikaisen prosessoinnin
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Pena, Alvarez Ana Azucena. „Micro/nano patterning of silicon and NiP/Al disks by nanosecond and femtosecond laser sources“. Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/micronano-patterning-of-silicon-and-nipal-disks-by-nanosecond-and-femtosecond-laser-sources(fcd519c6-bf51-4b73-b3ff-e3cbdd1bcffc).html.
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This PhD thesis presents the outcome of employing both nanosecond and femtosecond pulsed lasers in order to modify the surface structure of a material at the micro and nano scales. Literature review was carried out on micro/nano fabrication technologies involved in the semiconductor industry, which are the basis of many current micro and nano-manufacturing processes. The first experiments concentrated on direct laser scanning of Si to produce surface microstructures. This type of texturing was very effective at reducing surface reflectivity and can be implemented in photovoltaic devices. It was also found that the ablation efficiency can be improved if laser processing is performed in an argon environment where oxidation can be suppressed. Moreover, a significant relationship between laser-texture characteristics (i.e. topography/morphology and periodicity) and total surface reflectance was demonstrated. Short-circuit modelling of the laser texture showed that electrical performance of the cell can be improved by 41.3% in the 360-1100 spectrum, even in the near-infrared for which Si is a weak absorber. From these experimental results, it was also noticed that the laser-generated micro-structures made the surface significantly wettable; but as the laser fluence was reduced, the contact angle of the surface could be changed. This led to the investigation of the wetting properties of nano-bumps produced on Si at fluences below the ablation threshold. Their wetting behaviour was reported for the first time. An effect named as 'invisible marking' in this thesis was demonstrated: vapour condenses into water drops of different size depending on the lattice arrangement of c-Si or a-Si. Such an interaction at the near-ablation threshold was also explored for another type of material: NiP/Al data storage disks. From this research, elliptical bumps with vertical dimension in the sub-nanometre scale were fabricated with extremely high repeatability (± 0.4 nm). In addition, it was found that elliptical bumps can offer better stiction performance than circular shapes, even at ultra-low flying height. This type of laser texture could be utilised as a means for tribological optimization of surfaces that are in close proximity and relative motion. Following the use of low-fluences by nanosecond pulses, this was also applied to scanning over a microsphere lens array. So far, the research on near-field effects produced at the bottom of transparent particles has focused on how to generate parallel nano-patterns by single pulses. However, the present work has demonstrated that a focused beam with a tight-focus can be used to fabricate single lines or shapes rather than repeated patterns. In this way, a femtosecond laser was introduced to meet such a challenge. Moreover, laser-induced periodic surface structures (LIPSS) by fs pulses were also identified along the near-field generated nano-patterns. The evolution of such a periodic, self-assembly structuring was also investigated, and new optical characteristics of structural colour were found.
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Seghini, Maria Carolina. „Mechanical Analysis and Fibre/Matrix Interface Optimization for Next Generation of Basalt-Plant Fibre Hybrid Composites“. Electronic Thesis or Diss., Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2020. http://www.theses.fr/2020ESMA0003.
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La prise de conscience mondiale des enjeux environnementaux a conduit à l’émergence de composites«verts», dans lesquels les fibres naturelles sont amenées à remplacer les fibres synthétiques. Ces nouveaux matériaux offrent des alternatives écologiques aux composites synthétiques traditionnels mais sont difficilement utilisables pour des applications semi-structurales ou structurales. Une solution possible à ce problème est le développement des composites hybrides, en combinant ensemble fibres naturelles et synthétiques. Dans ce cadre, l'objectif de cette étude était de développer des composites hybrides à base de fibres de basalte et de lin. Les composites hybrides ont été élaborés par moulage par infusion sous vide avec une matrice époxy. À des fins de comparaison,des composites 100% à fibres de lin et100%à fibres de basalte ont également été produits. Une caractérisation mécanique quasi-statique et dynamique amontré que l'hybridation permet d’obtenir un composite avec des propriétés mécaniques intermédiaires comparées à celles des composites à fibres de lin ou de basalte. Cependant, l’analyse approfondie des dommages a montré la nécessité d'optimiser la qualité d'adhésion de l'interface fibre/matrice afin d'accroître les performances mécaniques des composites hybrides obtenus. Pour cette raison, différents traitements de modification de surface ont été développés et étudiés pour les fibres de lin et de basalte. Un traitement physique par plasma (Plasma Enhanced Chemical Vapor Deposition) a été appliqué aux fibres de lin et de basalte. Les fibres de lin ont également été soumises à deux traitements chimiques utilisant des espèces enzymatiques et du CO2supercritique. Les effets des traitements sur la stabilité thermique, la morphologie et les propriétés mécaniques des fibres de lin et de basalte ont été étudiés. L’adhérence fibre/matrice a été analysée en réalisant des tests de fragmentation sur des composites monofilamentaires. La qualité de l'adhésion entre les fibres et les matrices époxy et vinylester a été évaluée en termes de longueur critique de fragment, de longueur de décohésion interfaciale et de résistance au cisaillement interfacial. La micto-tomographie haute résolution a été utilisée pour analyser les mécanismes d'endommagement lors des tests de fragmentation. Pour les deux types de fibres, les meilleurs résultat sont été obtenus grâce au traitement par plasma. Ce traitement a consisté à déposer un revêtement homogène de tétravinylsilane à la surface des fibres de basalte et de lin, ce qui a permis une augmentation significative de l’adhérence fibre/matrice, ouvrant ainsi la voie à la prochaine génération de composites hybrides plus respectueux de l’environnement et utilisables pour des applications semi-structuralesGlobal awareness of environmental issues has resulted in the emergence of “green” composites, in which natural fibres are used to replace synthetic ones. However, in semi-or structural applications, it can be inconvenient to use composites based on natural fibres. A possible solution to this problem is the development of hybrid composite materials, combining together plies of natural and synthetic fibres. In this framework, the aim of this research project was to develop basalt-flax fibre hybrid composites with a view to obtaining more environmentally friendly composites for semi-structural applications. Hybrid composites were produced through vacuum infusion molding with epoxy matrix.For comparison purposes, 100% flax fibre composites and 100% basalt fibre composites were also manufactured. A quasi-static and dynamic mechanical characterization showed that the hybridization allows the production of a composite with intermediate mechanical performances compared to those possessed by flax and basalt composites. However, the damage analysis has revealed the need to optimize the fibre/matrix interface adhesion quality, in order to increase the mechanical properties of the resulting hybrid composites. For this reason, different surface modification treatments have been specifically designed and investigated for flax and basalt fibres. Flax and basalt fibres were treated by the physical process of Plasma Enhanced Chemical Vapor Deposition. Flax fibres were also subjected to two chemical treatments using enzymatic species and supercritical CO2. The effects of the surface modification treatments on the thermal stability, morphology and mechanical properties of flax and basalt fibres have been investigated. The degree and extent of fibre/matrix adhesion were analyzed by micromechanical fragmentation tests on monofilament composites. The adhesion quality between fibres and both epoxy and vinylester matrices has been assessed in terms of critical fragment length, debonding length and interfacial shear strength. High-resolution μ-CT has been used to support the analysis of the damage mechanisms during fragmentation tests. For both flax and basalt fibres, the best results were obtained after the plasma polymer deposition process. This process was able to produce a homogeneous tetravinylsilane coating on the surface of basalt and flax fibres, which resulted in a significant increase in the fibre/matrix adhesion, thus paving the way for the next generation of more environmentally friendly hybrid composites for semi-structural applications
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Lo, Yu-yun, und 羅御云. „Wetting Behavior on Zwitterionic Sulfobetaine Surfaces“. Thesis, 2015. http://ndltd.ncl.edu.tw/handle/69793398457647124586.
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碩士國立中央大學
化學工程與材料工程學系
103
In this study, (N,N-Dimethylaminopropyl)trimethoxysilane and 1,3-Propane sultone reacted to form Sulfobetaine silane(SBSi). SBSi is modified on glasses in the process of hydrolysis and condensation. By area and contact line variety to realize wetting behavior on SBSi substrates. Solution is divided into two sections, pure solution (water and hexadecane) and solution adding nonvolatile solute(cellobiose, poly(vinyl alcohol), poly(ethylene glycol), graphite oxide nanoparticle). Water spreads on SBSi substrates, area of water increasing. Then due to evaporation, area of water decreases. Hexadecane is nonvolatile solution. Hexadecane keeps spreading even passing an hour, area of hexadecane increasing. It indicates that SBSi substrates are superhydrophilic surfaces. Dipping solution on it, solution shows spontaneous spreading. Water and hexadecane are total wetting on SBSi substrates. When a SBSi substrate is placed in solution that with nonvolatile solute, bubble moves on substrates. As a result, it’s still total wetting. Nonvolatile solute deposition induces pinning behavior. In cellobiose, poly(vinyl alcohol) and graphite oxide nanoparticle solution experiments all indicate above results. Notably, poly(ethylene glycol)(PEG) solution is a special case. PEG solution doesn’t occur pinning behavior. Therefore, due to unequal evaporation rate, it can move non-directionally on level SBSi substrates. If let PEG solution deform, it can return to hemispherical shape no depending on another force. It shows that PEG solution is no hysteresis on SBSi substrates.
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Pratten, Don H. „Wettability and wetting behavior of elastomeric impression materials“. 1987. http://books.google.com/books?id=S6w9AAAAMAAJ.
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Wang, Tzu-Yu, und 王姿妤. „Exotic wetting behavior of surfactant drops on SBSi“. Thesis, 2017. http://ndltd.ncl.edu.tw/handle/82143038671779098633.
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碩士國立中央大學
化學工程與材料工程學系
105
The total wetting surface which is a kind of zwitterionic surface is fabricated by grafting the sulfobetain silane (SBSi) on glass slices. It is considered that there is a water film on the surface because of highly hydrate chemical groups. It can be observed different contact angle with dropping diiodomethane on SBSi which is in different relative humidity (RH). With increasing the relative humidity, the contact angle is larger in the reason that diiodomethane is insoluble in water. The other indirect evident is that the maximum wetting area of water drops on SBSi surface grows because more equilibrium water molecules bring benefits to the spreading of liquid. In the same ambient, it is observed the enormously different behavior between wet and dry surface no matter which electric charge surfactant droplets drop on the SBSi surface. When the liquid droplets drop on the SBSi surface containing a water film in the atmosphere, the droplets show the different behaviors depending on the electric charge of surfactant. Experiments show that droplets of cationic surfactant on SBSi surface present the phenomena of dewetting, because surfactant ions would be adsorbed on the SBSi surface. However, the droplets tend to stick on the dry surface and the contact angle of drops is about 40. For the case of anionic and nonionic surfactant, it shows the fingering pattern on the wet SBSi surface and the wetting behavior on the dry one.
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Tu, Sheng-Hung, und 涂勝宏. „Wetting behavior on copper wafers after etch cleaning processes“. Thesis, 2014. http://ndltd.ncl.edu.tw/handle/99724006810611796942.
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博士國立中央大學
化學工程與材料工程學系
102
The thin CuO flm is acquired by a quick dip of copper in H2O2 solutions at room temperature. The CuO filmq appears smooth and exhibits superhydrophilic nature. The composition change cannot be verifed by X-ray photoelectron spectroscopy but can be manifested by the water contact angle. In the ambient condition, the thickness of the oxidized layer and the surface hydrophobicity grow gradually, while the chemical composition of the overall oxidized film remains essentially unchanged. That is, in the vacuum, the growth rate of the hydrophobicity is significantly elevated, revealing deoxidation on the upmost surface. Our results indicate that growing hydrophobicity on the CuO film is spontaneous and the reversible wettability transition can be observed by H2O2 oxidation and vacuum deoxidation. The wet cleaning process in semiconductor fabrication often involves the immersion of the copper wafer into etching solutions and thereby its surface properties are significantly altered. The wetting behavior of a copper film deposited on silicon wafer is investigated after a short dip in various etching solutions. The etchants include glacial acetic acid and dilute solutions of nitric acid, hydrofluoric acid, and tetramethylammonium hydroxide. A thin oxide layer always remains on the surface of as-received Cu wafers when they are subject to etching treatments. A pure Cu wafer can be obtained by the glacial acetic acid treatment and its water contact angle (CA) is about 45. As the pure Cu wafer is placed in the ambient condition, the oxide thickness grows rapidly to the range of 10 to 20 Å within 3 hours and the CA on the hydrophilic surface also rises. In the vacuum, it is surprising to find that the CA and surface roughness of the pure Cu wafer can grows significantly. These interesting results may be attributed to the rearrangement of surface Cu atoms to reduce the surface free energy.
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Liu, Shue-Ching, und 劉淑卿. „Wetting behavior of Na2O-Al2O3-P2O5 glasses at high temperature“. Thesis, 2003. http://ndltd.ncl.edu.tw/handle/78050544214403923416.
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碩士大同大學
材料工程研究所
91
Abstract Sessile drop method is used to discuss the derive difference in wetting angle、density and surface tension by using contact angle measurement instruments. The melting Na2O-Al2O3-P2O5 glass is placed on a platinum substrate, whose composition is changed（increase Al2O3 ratio and relatively decrease Na2O、P2O5 ratio）. In this experiment, drying mixing method is used to mix oxide（NaH2PO4•H2O and α- Al2O3）. The Na-Al-P glass is prepared by melting the mix oxide in the high temperature, and it is identifyed by XRD identification、ICP analysis、DTA analysis、TMA analysis、contact angle ( θ ) and surface tension (σ) measurement. From the XRD identification, the productions of Na-Al-P glass show amorphous phase. Due to the result of ICP, there is only slight deviation in the compo-sition of the glasses. The DTA result can be observed the crystalline temperature (TP ) of Na-Al-P glass. The outcome of the softening point temp- erature (Tds )、glass transition temperature (Tg ) and coefficient of thermal expansion (α) of Na-Al-P glass can be measured in TMA. The thermal expansion coefficient reduced and Tg、Tds increased of Na-Al-P glass as the increased ratio of Al2O3 ( which confirm to the literature ). From the result of DTA , the TP of the NP46.3A7.5 composition is 572.79℃, which is the most high temperature among the five compositions. The difference between TP and Tds of NP46.3A7.5 is the maximum value for five compositions. The NP46.3A7.5 is the more stable composition for all samples from the result of the wetting test.
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Wang, Yu-Qian, und 王育謙. „Wetting Behavior Between Electroless Nickel and Sn-Zn-Al Solder“. Thesis, 1997. http://ndltd.ncl.edu.tw/handle/02008454074858220984.
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Huang, Rui-Hong, und 黃瑞鴻. „Orientational Wetting Behavior of Liquid Crystal Mixtures on the Glass“. Thesis, 1998. http://ndltd.ncl.edu.tw/handle/26266778366246306680.
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Wang, Yu-Chien, und 王育謙. „Wetting Behavior Between Electroless Nickel and Sn-Zn-Al Solder“. Thesis, 1997. http://ndltd.ncl.edu.tw/handle/38467090652350630105.
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碩士國立成功大學
材料科學(工程)學系
85
This study is to investigate the wetting behavior between the copper substrate which was deposited with electroless nickel as a diffusion barrier for the ternary eutectic Sn-Zn-Al solder. The copper plating was deposited on the electroless nickel to improve the wetting behavior. The wetting experiment was conducted with the wetting balance for the two systems of Cu/Ni- P and Cu/Ni-P/Cu Plating at various temperature and fluxes. The interfacial reactions between the solder and these two systems after heat treatment were examined with Scanning Electron Microscope and with X-ray diffraction. The contact angle investigation was applied for estimating the temperature needed for the occurrence of solder wetting without flux. The experimental results for the Ni-P/solder system showed that good wetting was achieved only at high temperature (above 350℃) and with high concentration of active fluxes (above 5g/l DMAHCl). The solder layer contains pores. The crystallization of electroless nickel layer and less active fluxes could not improve wetting. The experiment results of the Ni-P/Cu system showed that the surface coverage of solder on Ni-P/Cu was more than that on Ni-P at low concentration of fluxes (above 2.5g/l DMAHCl), although it also showed partial wetting. The results of the interfacial elemental line - scanning showed that the Zn atom diffused to the interface between the solder and copper. The X-ray showed that the interaction between solder and Ni-P/Cu resulted in the formation of g-Cu5Zn8 compound which further avoids the tin diffusing into the layer of copper plating.
44
Hsu, Chia-Hao, und 許家豪. „The wetting behavior of polymeric drop on polymer brush surfaces“. Thesis, 2017. http://ndltd.ncl.edu.tw/handle/b9zy3w.
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碩士國立臺灣大學
化學工程學研究所
105
The study of the stability of polymeric thin films on solid substrates is of significant importance in many practical applications such as the manufactures of organic solar cells and organic light-emitting diode. However, films on nonwettable substrates tend to exhibit unstable behavior. To resolve this issue, the modification of a nonwettable surface can be accomplished by coating the surface with an appropriate monolayer. Polymer brush is a typical example of applicable candidates. However, an autophobic behavior is observed due to entropic repulsion even if the brushed layer is composed of identical molecules as those forming the films. In this work, dissipative particle dynamics is performed to study the wetting phenomena of polymeric thin films on top of solid substrates or surfaces coated polymer brush. We start by investigating the effects of polymer length and solid-liquid affinity on the shape and contact angle of a polymeric droplet. The interfacial tensions of solid-liquid, solid-gas and liquid-gas are measured and the Young’s equation is employed to estimate the contact angle. The resulting contact angles are consistent with those obtained directly from simulations verifying that validity of our simulation work. The influences of the molecular lengths of the polymeric films and polymeric brushes on the wetting behaviors of the coated films are examined. It is found that the wettability can be improved by decreasing the molecular lengths of the polymeric films while increasing the lengths of polymer brushes. The stability of a thin film depends on the penetration length of the polymers into the brush layers. Moreover, there exists a critical value of grafting density beyond which the autophobic behavior becomes significant as grafting density increases. The rupture process of a polymer thin film has also been studied. The dewetting velocity increases with increasing grafting density. Our simulation results are consistent with the experimental observation and can be applied to improve adhesion of polymeric thin films on a solid substrate.
45
Xu, Wei-Shiang, und 徐惟祥. „Spreading Behavior of Drops on a Total Wetting Surface：MDPD Simulation“. Thesis, 2017. http://ndltd.ncl.edu.tw/handle/56491894009021587103.
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碩士國立中央大學
化學工程與材料工程學系
105
Liquid drops spontaneously spreading on a solid surface is referred to as the total wetting phenomenon. A typical example is the continuous expansion of a silicon drop on various surfaces. The time evolution of the drop radius can be described by the power law r(t) ∼ tn with the exponent 1/10, known as Tanners law. In this work, the spreading dynamics of a nanodrop on a total wetting surface under saturated humidity and no-slip condition has been explored by many-body dissipative particle dynamics simulation. The influences of surface roughness and wettability in terms of spreading coefficient on the spontaneous spreading behavior are studied. It is found that the exponent n is 0.2 on smooth surface, and the exponent grows with increasing the spreading coefficient. The reason for the difference with Tanner’s law is that the formation of precursor film with the drop spreading process. As we remove the effect of the precursor film, the drop radius and contact angle behavior agree with Tanner’s law and the spreading law is independent of the spreading coefficient. In addition, The drop spreading velocity on rough surface is lower than that on smooth surface and the spreading process also follow Tanner’s law. It shows the surface roughness will prevent the growing of the precursor film and the resistance rises with increasing the cavity size. Furthermore, the drop spreading velocity is significantly lower and the drop becomes very thin for a long time because the most of the liquid beads stuck in the cavity. The forced spreading that is similar to the thin film flow on the surface under external force are investigated as well. As a result, the drop spreading motion which is vertical to external force also consistent with Tanner’s law and the precursor film is produced in the spreading process with this direction. On the forced direction, the rear part of the liquid drop will slide on smooth surface due to without surface roughness that can make pinning force to impede the movement of the contact line. In contrast, the rear part of the liquid drop will pinning on rough surface. Moreover, the precursor film can’t be observed on forced direction, since the forced flow velocity is faster than the velocity of expansion with precursor. In addition, the flow velocity with the forced direction will be affected by the precursor and the surface roughness will make the flow velocity significant slower.
46
Yeh, Ming-Chih, und 葉銘智. „A Study of Effect of Molecular Structure on Wetting Behavior“. Thesis, 2003. http://ndltd.ncl.edu.tw/handle/54233306699418977739.
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博士國立臺灣大學
化學工程學研究所
91
For three phases, alpha, beta,and gamma in equilibrium, the wetting behavior of the middle beta phase can be easily realized by the contact angle spanned by the alpha and the gamma interfaces, such as nonwetting, partial wetting, and complete wetting. The transition from a partial wetting regime to a complete wetting (or nonwetting) regime, or vice versa, is called a wetting transition. A wetting transition was found to be induced by altering thermodynamic variables, such as temperature, pressure, and salinity, etc, to bring the system close to its criticality. It was also pointed out that a wetting transition might be more relevant to the preferential adsorption behavior at interface or the short-range intermolecular forces rather than the critical phenomena. In this work, the effect of molecular structure on wetting behavior was both experimentally and theoretically investigated. In the experimental section, alcohols which including linear-chain alcohol, branched-chain alcohol, and linear-chain alcohol with additional oxyethylene groups, were chosen to examine the effect of structure upon wetting transitions. By employing surface and interfacial tension measurement, the wetting behavior and the location of a wetting transition could be deduced. It was found that for the water + linear alcohol homologs systems, the alcohol-rich phase tends to completely wets the air-aqueous interface as chain length decreases. For water + polyoxyethylene alcohol systems, a wetting transition from partial wetting nonwetting may occur with decreasing temperature and increasing number of oxyethylene groups. For water + isomeric alcohol systems, a wetting transition from partial wetting to complete wetting takes place while the molecular structure changes from a primary linear alcohol to a tertiary branched alcohol. Otherwise, in the theoretical approach, the influences of intermolecular force, molecule size, and molecule anisotropy on wetting phenomena were scrutinized by two density functional theories (DFT). The effect of tuning intermolecular forces was analyzed by a density functional theory combined with statistical associating fluid theory (SAFT-DFT), and good agreements with experimental results for water + polyoxyethylene alcohol systems were achieved. In addition, the order of a wetting transition was also found to be fine tuned by the range of attraction force and the association strength. Two wetting transitions with different orders in one system are revealed in this calculation. Besides, the sequential transitions from nonwetting partial wetting complete wetting for water + oil + alcohol mixtures was observed to be associated with the amphiphilicity of the alcohol. Finally, the molecular anisotropy was considered using an interaction site model coupled with a density functional theory (ISM-DFT). This method was applied to examine the influence of hydrocarbon-chain structure, flexibility, and the hydrophilicity of the polar head. The wetting transition induced by molecular structure change was successfully predicted. Furthermore, satisfactory predictions for the effect of chain length and hydrophilicity upon wetting behavior are also illustrated.
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Su, Cheng-Hao, und 蘇晟豪. „A Study on Phase Behavior and Wetting Behavior of the Ternary Water + Oil + CiPj System“. Thesis, 2011. http://ndltd.ncl.edu.tw/handle/27558504128881170960.
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博士國立臺灣大學
化學工程學研究所
99
In this study, we investigate the phase behavior and the wetting behavior of the ternary water + oil + nonionic surfactant system. The oils are n-alkanes and the nonionic surfactants are CiPj. The symbol CiPj is the abbreviation of a propylene glycol ether CH3(CH2)i-1(OCH2CH(CH3))jOH. There are three-liquid-phase- coexisting regions in water + decane + C3P1, water + dodecane + C3P1, water + tetradecane + C3P1, water + hexadecane + C3P1, water + dodecane + C3P2, water + tetradecane + C3P2, and water + hexadecane + C3P2 systems. Experiments of fish-shaped phase diagrams for these seven systems under atmospheric pressure were performed at constant water/n-alkane weight ratio (1/1) to locate the critical end points. The ternary system of the alkane with the longer carbon chain length has the higher upper and lower critical solution temperatures and the larger three-liquid-coexisting temperature window in the fish-shaped phase diagram. The upper and lower critical solution temperatures are lower in these systems with larger j number of C3Pj. Precise liquid-liquid equilibrium data of mixtures for six ternary systems water + alkane (dodecane, tetradencane, and hexadecane) + C3Pj (j=1 or 2) under atmospheric pressure were determined by using gas chromatography. The evolution of phase behavior of the ternary water + n-alkane + C3Pj system as a function of temperature is qualitatively consistent with that of the water + oil + CiEj system. The experimental liquid-liquid equilibrium data were successfully correlated with the NRTL model. We use pedant drop method to measure the interfacial tensions and investigate the wetting behavior of four ternary systems, water + dodecane + C3P1, water + tetradecane + C3P1, water + hexadecane + C3P1, and water + hexadecane + C3P2 system. In these ternary systems, the middle surfactant-rich phase exhibits complete wetting in the temperature window of the three-liquid-phase-coexisting region.
48
Woracek, Robin. „Wetting Behavior of Polymer Melts with Refractory Coatings at High Temperature“. 2009. http://trace.tennessee.edu/utk_gradthes/574.
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Within the scope of this thesis, an experimental system has been designed, developed and manufactured for the determination of the wetting behavior of liquids and polymer melts with solid surfaces (coated and uncoated) at high temperatures (> 200 ºC). The measurement system incorporates a modified Wilhelmy plate technique, using a precision weighing module, a vertical linear stage, custom developed application software using LabView with suitable hardware and a high temperature furnace with thermocouple feedback control. Experiments have been performed and are reported to evaluate the performance of the testing system, using liquids of known wetting properties. A suitable testing procedure based on dynamic Wilhelmy plate theory is proposed, involving investigation of advancing and receding liquid-probe interactive forces and hysteresis loops.
Interfacial wetting and wicking behavior of polystyrene melt with clay based refractory coatings, as used in the lost-foam casting (LFC) process, are presented a function of temperature using this measurement system. Experiments of particular interest were performed for two different types of refractory coating and for polymer melts at processing temperatures between 220°C and 300°C, where they show pronounced viscoelastic behavior. Different variables, obtained from the hysteresis loops, were utilized as quantitative indicators for comparison, including the area under the loop from contact onwards, the slope of advancing and receding lines in the force-displacement domain, the force hysteresis at zero displacement and Fast Fourier Transform (FFT) analysis of the hysteresis loop.
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Hong, Ting-Syu, und 洪庭旭. „Wetting Behavior of Surfactant Solutions on Hydrophobic Surfaces: Copper and Teflon“. Thesis, 2007. http://ndltd.ncl.edu.tw/handle/14722073420473158256.
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碩士國立中央大學
化學工程與材料工程研究所
95
Drop wetting on material surface that is decided by Young’s equation. Gas-solid tension, solid-liquid tension and liquid-gas tension are balance on wetting substrate. Between liquid and solid is display a angle that the angle is call: “Contact Angle”. In the research, steady of wetting behavior of surfactant solutions on the hydrophobic surfaces: Copper and Teflon. We know that have low γsg (Cu=21.2mN/m,Teflon=6.78mN/m) and high contact angle (Cu~100°,Teflon~130°) on Cu and Teflon surfaces. Because of hydrophobic property surfaces, therefore use surfactant solutions to decrease γgl,γsl and contact angle for achieve wetting effectiveness. We find out contact angle of nonionic surfactants are not change when reach CMC, but contact angle of anionic surfactants are continue decrease when reach high CMC on Cu and Teflon surfaces. Contact angle of cationic surfactants are not change on Cu surface, but that continue decrease when reach concentration on Teflon surface. However, contact angle of two tail ionic surfactants are always continue decrease with concentration increase on Cu and Teflon surfaces.
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Yang, Yung-Jih, und 楊詠茹. „Modeling the Wetting Behavior of Heterogeneous Patterned Surface by Numerical Method“. Thesis, 2011. http://ndltd.ncl.edu.tw/handle/03792616605172661827.
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碩士國立臺灣大學
化學工程學研究所
99
There are two sections in our studies. First part is a simple and cheap method for fabrication of superhydrophobic surface and the wetting behaviors on structured hydrophilic or hydrophobic surfaces are also studied. The other part is the study of wetting behavior on 2 μm striped heterogeneous surface. Wetting behavior plays an important role in various industries, and has been studied for a long while. Lower the surface energy and enhance the surface roughness are the method to prepare superhydrophobic surface. We are able to combine and modify a soft-embossing technique and surface modification of a self-assembled monolayer to establish a standard operation procedure for manufacturing superhydrophobic surfaces. Two issues are addressed in this part of study. First, the water contact angles of surfaces without modification are discrepant with the Wenzel and Cassie models. Second, the different polymer surfaces with modification can change their characteristics from hydrophilicity to hydrophobicity. Further, different polymer surfaces have the same contact angle only if they have the same structure before modification. And the results are quite consistent with Wenzel and Cassie models. Besides, we examine contact angle of liquid droplet on 2 μm striped surface by the Matlab modeling and also determine equilibrium contact angle (ECA), advancing contact angle (ACA) and receding contact angle (RCA) from free energy curve obtained by the Surface Evolver. The ECA (78°) from the Matlab modeling is totally consistent with the Cassie model, but is quite different from the results (83°~85°) shown in the Surface Evolver. However, the tendencies of ECAs from both methods are the same – oscillation with small liquid and approaching a constant with larger liquid. In our system, ACA is always a constant (110°) but RCA is volume-dependent. RCA oscillates at first, and finally falls into a certain narrow region (70°~80°). Our result also indicates that the contact line of liquid drop inclines to be a slightly ellipse-like shape, not a perfect circle-like shape. Further, we make a discussion about the thickness of contact angle transition region. The dimensionless thickness from hydrophobic to hydrophilic surface is almost 0.22, and the dimensionless thickness from hydrophilic to hydrophobic surface decreases from 0.02 to 0.0027 as increasing liquid volume.