A capillary barrier develops and restricts water flow when two porous materials with dissimilar pore structures (e.g., a coarse-grained soil overlain by a fine-grained soil) are in contact with one another. This is due to a difference in the unsaturated hydraulic conductivity of the two materials at a given suction. Geotextiles are utilized in a variety of civil engineering applications and have a pore structure similar to that of a coarse-grained soil. This can be problematic in unsaturated soil as the capillary barrier caused by the geotextile may instigate undesirable moisture buildup in the overlying soil and undermine any benefit provided by the geotextile. Various versions of a new geotextile have been manufactured to help dissipate a capillary barrier by "wicking" or laterally draining excess moisture away from the soil. Additionally, nonwoven blends of the unique wicking fiber combined with standard polymeric fibers are tested to assess their ability to minimize the development of a geotextile capillary barrier and not cause additional moisture accumulation in the first place. The unsaturated properties of both woven and nonwoven configurations of these wicking geotextiles were investigated as part of a comprehensive an experimental testing program. The testing program includes small soil column infiltration tests to assess geotextile capillary barrier performance with moisture monitored by time domain reflectometers and capacitance probes. Also, modified hanging column tests were conducted to define the hydraulic properties of the geotextiles in the form of water retention curves. Finally, a microscopy study, involving both optical and scanning electron microscopes, was conducted to observe the wicking behavior of the geotextiles at a micro-scale level. Test results illustrate the enhanced lateral drainage and reduced moisture accumulation of the wicking geotextiles when compared to regular geotextiles. Additionally, the woven version of the wicking geotextile has the potential to perform the functions of separation, filtration, protection, reinforcement, and drainage. All of these functions in a single geosynthetic product could lead to significant cost savings compared to the use of separate products to perform each one of the various functions. / text

Syftet med rapporten är att utvärdera och jämföra två standarder, AATCC Test method 198-2011: Horizontal Wicking of Textiles och AATCC Test method 197-2011: Vertical Wicking of Textiles. Standarderna publicerades år 2011 av American Association of Textile Chemists and Colorists. Standarderna mäter wicking, det vill säga, med vilken hastighet som vätska transporteras genom textil, med en horisontell och en vertikal testmetod. Hastigheten anges i olika enheter beroende på standard, enheten för AATCC Test method 197-2011: Vertical Wicking of Textiles är mm/s och AATCC Test method 198-2011: Horizontal Wicking of Textiles anges i mm2/s. Skillnaden i enhet och mätmetod innebär att standarderna inte kan jämföras rakt av genom resultat och mätvärden mellan de båda standarderna. Utvärderingen kan därför endast utföras med hjälp av mätprecision, vilken standard som kan tillämpas på flest tygkvaliteter och hur nära mätresultatet ligger verkligheten i vardera standard. Ytterligare en del i rapporten är att undersöka om tygkvaliteter som kan testas av standarderna före tvätt, förändrar sina egenskaper efter tvätt så att en provning är möjlig.Provningen utfördes enligt den metod från standarder i en standardiserad miljö på Textil och läderlaboratoriet i Stockholm. Testmetoden för AATCC Test method 198-2011: Horizontal Wicking of Textiles är att droppa vätska på ett horisontellt placerat tygprov. Mätningen tar ingen hänsyn till vätskans spridningsriktning i tyget. Testmetoden för AATCC Test method 197-2011: Vertical Wicking of Textiles är att en tygremsa placeras i en bägare så att ena kortänden har kontakt med vätskan och transporteras upp i tygprovet. Testet har två olika nivåer att mäta hastigheten vid, en kort och en lång. Provning sker med tygprover i både varp- och väftriktning, då riktningen påverkar resultatet.För att få en indikation på vilka material som kan tillämpas på vardera standard utförs testmetoderna på provmaterial med en stor variationsbredd i materialkomposition, konstruktion och behandling. Provresultaten skiljer standarderna åt och en tydlig trend visar att den ena standarden gav ett mer tillförlitligt resultat än den andra oberoende av variation på material.Standard AATCC Test method 197-2011: Vertical Wicking of Textiles kan tillämpas på fler tygkvaliteter än standard AATCC Test method 198-2011: Horizontal Wicking of Textiles. Ingen av standarderna kunde appliceras på hydrofoba tygkvaliteter. För standard AATCC Test method 198-2011: Horizontal Wicking of Textiles var vätskemängden för stor för att vissa av de utvalda tygkvaliteterna skulle kunna absorbera och transportera vätska. Vätskan droppade igenom tyget och gav ett ej tillförlitlig mätresultat av wicking. Med stöd i en statistiskanalys och jämförelse mellan standarderna gav även AATCC Test method 197-2011: Vertical Wicking of Textiles ett statistiskt säkrare provresultat med lägre varians i de olika materialen. Provmaterial som inte var tillämpbara på standarderna ändrade ej sina egenskaper efter en tvättbehandling i så stor utsträckning att en tillämpning på någon av standarderna kunde göras.The aim of this study where to evaluate two standards, Horizontal Wicking of Textiles: AATCC Test Method 198-2011 and Vertical Wicking of Textiles: AATCC Test Method 197-2011. They where published in 2011 by the American Association of Textile Chemists and Colorists. Both of them measure the wicking rate through a textile. The two standards measures two different units, for Test Method 197-2011 it´s mm/s and for Test Method 198-2011 it´s mm2/s. The difference in units results in different applications. Therefore the evaluation between them only concerns measurements precision, the materials range of variation within each standard and how near the true value the measurements are to reality. An additional parameter that were analyzed is how applicable material for the standards changes characteristics, if the material becomes applicable after one washing treatment or not.The test where conducted according to the standards in a standard environment at the Textile and Leather Laboratory in Stockholm. The course of action for Test Method 198-2011 where to drip liquid unto a horizontal placed impactor. Then measure the longest way the liquid wicked in warp and weft direction. Test Method 197-2011 where conducted in both warp and weft direction, which gave a markedly difference in the responses. The method´s execution where to place a fabric strip in an Erlenmeyer flask containing liquid. The fabric strip where placed so only the tip where under the surface. There where to levels where measures was supposed to be taken, one short and one long.By contucting the test methods on materials that had a range of variation in fiber contents, construction and finishing, gave an indication of what kind of material that could be evaluated in each standard. The results differed the standards and a distinct trend showed that one of the standards had a more reliable result than the other, independent of the range of variation in the materials. Test Method 197-2011 could be used on every material in this study expect from the ones that where hydrophobic. This was a significant difference from Test Method 198-2011. The method had a quantity of liquid that much of the materials couldn´t absorb and wick. The liquid dripped through and gave a not reliable result. With the support of a statistical analysis and comparison between the standards, the Test Method 197-2011 gave a statistical reliable result with a lower variance in most of the materials. The materials that were not applicable on the standards did not change its characteristics after one washing, which did not make it more suitable for the standards. / Program: Textilingenjörsutbildningen

The growth of fossil fuel production in North Dakota has resulted in numerous releases of brine. Brine releases cause vegetation mortality as well as the deterioration of soil structural and edaphic properties. Little research to date has been dedicated to the germination response of plant species grown in North Dakota to brine-induced salinity. Through the exposure of plant seeds to increasing levels of brine and NaCl-induced salinity, it was determined that the graminoid species Elymus hoffmannii (AC Saltlander) and Pascopyrum smithii (Western Wheatgrass) exhibited the greatest germination at high salinities. Current remediation technologies for brine-impacted lands often produce mixed results, requiring further research and testing. In two laboratory experiments, the ability of materials to wick salts from brine-contaminated soils was tested. The results of these studies show that some materials reduced Na concentrations in sandy loam, loam, and silty clay soils by upwards of 88, 89.5, 38.4% respectively.

The earliest man-made irrigation systems in recorded history date back to the ancient Egypt and Mesopotamia era. After thousands of years of experience, exploration, and experimenting, mankind have learned how to construct canals and dams and use pipes and pumps to direct and control water flow, but till this day, there are still some behaviors of water and other simple fluids that surprise us. One such example is the lotus effect: a surface-tension effect which allows raindrops to roll freely on a lotus leaf as if they were drops of mercury. One of the key factors that determine how a fluid system behave is the size-scale. Fluids flow at small scales very differently than they do at large scales. The standard comparing to which small and large are defined is the capillary length. A number of surface-tension related phenomena are unfamiliar because they are only noticeable at length-scales of a few millimeters or below, and they look nothing like what we would expect fluids to behave when dominated by gravity. As fascinating as many of them may seem at first glance, surface-tension phenomena are actually not that far away from our daily lives. Surface tension is everywhere because it costs energy to create areas of surfaces and interfaces, just like it costs energy to deform a solid (resulting in elasticity) or to elevate a weight (resulting in gravity). To minimize energy, a surface or an interface has the tendency to contract, and this tendency generates surface tension. The size of a system significantly affects the relative strengths of surface-tension effects comparing to effects of body forces, most commonly gravity. By equating the estimated magnitudes of surface tension and gravitational forces of a system, a length scale, know as the capillary length, can be defined. The capillary length of water on earth is about 2.7 mm. At the length scale of everyday objects, which is usually above the capillary length, surface-tension effects are not always prominent, because at those scales the competing force, gravity, is often much stronger. That is why the surface of a glass of water is more or less flat. However, as the size-scale decreases, surface tension decreases a lot slower than gravity, so when the size of a fluid system gets down to below the capillary length, surface tension takes over. One of the defining characteristics of this moment in human history, is the tremendous efforts we are putting into the research and engineering of micro- and nano-scale materials and structures − systems where surface tension is often the predominant force. It is important to study surface-tension effects so that we can use them to our advantage. In this Ph.D. dissertation, we have investigated some important surface-tension phenomena including capillarity, wetting, and wicking. We mainly focus on the geometric aspects of these problems, and to learn about how structures affect properties. Understanding these phenomena can help develop fabrication methods (Chapter 2), study surface properties (Chapter 3), and design useful devices (Chapter 4) at scales below the capillary length. In the first project (Chapter 2), we used numerical simulations and experiments to study the meniscus of a fluid confined in capillaries with complicated cross-sectional geometries. In the simulations, we computed the three-dimensional shapes of the menisci formed in polygonal and star-shaped capillaries with sharp or rounded corners. Height variations across the menisci were used to quantify the effect of surface tension. Analytical solutions were derived for all the cases where the cross-sectional geometry was a regular polygon or a regular star-shape. Power indices that characterize the effects of corner rounding were extracted from simulation results. These findings can serve as guide for fabrications of unconventional three-dimensional structures in Capillary Force Lithography experiments [J. Feng (2011) (a)]. Experimental demonstrations of the working principle was also performed. Although quantitative matching between simulation and experimental results was not achieved due to the limitation of material properties, clear qualitative trends were observed and interesting three-dimensional nano-structures were produced. A second project (Chapter 3) focused on developing techniques to produce three-dimensional hierarchically structured superhydrophobic surfaces with high aspect ratios. We experimented with two different high-throughput electron-beam-lithography processes featuring single and dual electron-beam exposures. After a surface modification procedure with a hydrophobic silane, the structured surfaces exhibited two distinct superhydrophobic behaviors − high and low adhesion. While both types of superhydrophobic surfaces exhibited very high (approximately 160_) water advancing contact angles, the water receding contact angles on these two different types of surfaces differed by about 50_ _ 60_, with the low-adhesion surfaces at about 120_ _ 130_ and the high-adhesion surfaces at about 70_ _ 80_. Characterizations of both the microscopic structures and macroscopic wetting properties of these product surfaces allowed us to pinpoint the structural features responsible for specific wetting properties. It is found that the advancing contact angle was mainly determined by the primary structures while the receding contact angle is largely affected by the side-wall slope of the secondary features. This study established a platform for further exploration of the structure aspects of surface wettability [J. Feng (2011) (b)]. In the third and final project (Chapter 4), we demonstrated a new type of microfluidic channel that enable asymmetric wicking of wetting fluids based on structure-induced direction-dependent surface-tension effect. By decorating the side-walls of open microfluidic channels with tilted fins, we were able to experimentally demonstrate preferential wicking behaviors of various IPA-water mixtures with a range of contact angles in these channels. A simplified 2D model was established to explain the wicking asymmetry, and a complete 3D model was developed to provide more accurate quantitative predictions. The design principles developed in this study provide an additional scheme for controlling the spreading of fluids [J. Feng (2012)]. The research presented in this dissertation spreads out across a wide range of physical phenomena (wicking, wetting, and capillarity), and involves a number of computational and experimental techniques, yet all of these projects are intrinsically united under a common theme: we want to better understand how simple fluids respond to small-scale complex surface structures as manifestations of surface-tension effects. We hope our findings can serve as building blocks for a larger scale endeavor of scientific research and engineering development. After all, the pursue of knowledge is most meaningful if the results improve the well-being of the society and the advancement of humanity.

<p>Edge wicking, i.e. in-plane wetting, is an important parameter for liquid packaging board products. Before filling of the products at the dairy the web is being sterilised with hydrogen peroxide (H2O2). A tube is shaped and cut into packages which mean that new surfaces are created. If a short stop occurs in the sterilising bath the raw edges exposed to H2O2 could absorb the liquid and when the package later is being filled this absorption could lead to tube burst. For the end products it is also important to prevent the liquid from penetrating the raw edges of the board in order to maintain the functionality and fresh look of the package.</p><p>To control edge wicking different kinds of internal hydrophobic sizing agents are used. Alkyl ketene dimer (AKD) is the most common size in neutral sizing and rosin in conjunction with alum is the traditional acidic sizing agent. AKD and rosin size are often used in combination (dual sizing) to make the board hydrophobic.</p><p>The objective of this work was to examine the effects of the sizing agents on different pulps in different dosages. The pulps used in the sheet preparation were unbleached kraft pulp as well as bleached and unbleached CTMP refined to different levels. Apart from varying the size dosages, the wet sheets were also pressed at different levels to vary the density. The major part of the study included dual sizing but a minor part also concerned mono sized sheets.</p><p>The parameters investigated on the laboratory sheets were STFI-Density, hydrogen peroxide edge wicking, pressurised edge wicking, lactic acid edge wicking (LA) and AKD and rosin size content.</p><p>In hydrogen peroxide edge wicking the amount of size was the central source of improved wick index. The retention was therefore of great significance for the results. The dual sized sheets were found to give least edge wicking, due to the synergy effect between AKD and alum rosin size. The kraft pulps gave sheets with satisfactory edge wicking even at the lowest size dosage (1 kg/t) while CTMP required a dosage of 4 kg/t to reach the same wick index.</p><p>To achieve acceptable pressurised edge wicking values the most important parameter was found to be the density of the sheets. The kraft pulp sheets gave the lowest edge penetration while the high freeness CTMP sheets did not give satisfactory penetration resistant even at the highest size dosage.</p><p>The edge wicking of lactic acid could be prevented by sizing with AKD only. Sheets made from mono sized sheets containing rosin size did not manage to avoid a large in-plane wetting of the board structure. Hence, dual sizing to improve the edge wicking of lactic acid is not necessary. The density was found not to be an important parameter in lactic acid edge wicking, all the pulps got equal edge wicking regardless of density. Retention above 1 kg/t AKD in sheets was enough to prevent penetration. Retention above 1.5 kg/t AKD in sheet did not improve the edge wicking any further.</p><p>No significant difference in sizeability between unbleached and bleached CTMP was observed.</p>

A method used to calculate the fundamental properties that predict the overall wicking performance of a fabric was proposed and executed. The combination of a horizontal and downward wicking test provided detailed measurements of the pertinent properties to wicking performance: capillary pressure and permeability. This method was proposed due to flaws found in standard vertical wicking tests as well as erroneous assumptions made in other wicking tests. Assumptions that capillary pressure and permeability are characteristic constants of porous structures are incorrect and will produce misleading information about that substrate. It was experimentally proven that these properties were a function of the saturation level found within the voids of a fabric. To obtain relevant capillary pressure and permeability data for a given fabric, a range of saturation levels were tested and analyzed. It was shown that saturation levels decreased as the vertical distance traveled by moisture increased. This phenomenon occurs as a result of capillary pressure within the voids dropping below the functional range needed to support flow in those voids at increasing heights. As height is increased, capillary pressure needs to also increase; therefore, only smaller radii pores will fill. Once saturation levels are known at specific heights, capillary pressure and permeability calculations were made using Darcys law and the Lucas-Washburn equation. Although this phenomenon is well known in civil engineering, it has not been widely addressed in the textile sciences, especially in its implications for wicking tests.

The wicking properties of multi-ply paper samples with dissimilar plies were investigated. These materials exhibit wicking performance in excess of either of their individual plies. Samples were produced from a ply of softwood pulp and a ply of hardwood pulp of equal caliper and basis weight. The softwood sample possessed a larger average pore size, a fact verified via porometry. Samples of a single ply were also produced for comparison. The samples were tested using both upward and downward gravimetric wicking tests. There was no saturation gradient observed, however there was a variation in the degree of bulk expansion during wicking. Capillary pressure and permeability for the various sample types were determined from the results of these tests and compared. It is shown that the wicking performance of the two ply sample is comparable to that of a theoretical material with the capillary pressure of the hardwood ply but the permeability of the softwood ply. Wicking in two-ply samples was also observed in an NMR apparatus. This was used to determine that the hardwood ply leads during wicking, and observe the rate of saturation as well as bulk expansion. A third type of experiment tracked the transport of dyed water from one ply to the other, establishing the direction of fluid transport during wicking to be from the softwood ply to the hardwood ply. The theory is proposed, based on these results, that wicking in this type of material consists of a smaller pored leading ply that draws water from a more permeable larger pored material that acts as a moving reservoir.

Edge wicking, i.e. in-plane wetting, is an important parameter for liquid packaging board products. Before filling of the products at the dairy the web is being sterilised with hydrogen peroxide (H2O2). A tube is shaped and cut into packages which mean that new surfaces are created. If a short stop occurs in the sterilising bath the raw edges exposed to H2O2 could absorb the liquid and when the package later is being filled this absorption could lead to tube burst. For the end products it is also important to prevent the liquid from penetrating the raw edges of the board in order to maintain the functionality and fresh look of the package. To control edge wicking different kinds of internal hydrophobic sizing agents are used. Alkyl ketene dimer (AKD) is the most common size in neutral sizing and rosin in conjunction with alum is the traditional acidic sizing agent. AKD and rosin size are often used in combination (dual sizing) to make the board hydrophobic. The objective of this work was to examine the effects of the sizing agents on different pulps in different dosages. The pulps used in the sheet preparation were unbleached kraft pulp as well as bleached and unbleached CTMP refined to different levels. Apart from varying the size dosages, the wet sheets were also pressed at different levels to vary the density. The major part of the study included dual sizing but a minor part also concerned mono sized sheets. The parameters investigated on the laboratory sheets were STFI-Density, hydrogen peroxide edge wicking, pressurised edge wicking, lactic acid edge wicking (LA) and AKD and rosin size content. In hydrogen peroxide edge wicking the amount of size was the central source of improved wick index. The retention was therefore of great significance for the results. The dual sized sheets were found to give least edge wicking, due to the synergy effect between AKD and alum rosin size. The kraft pulps gave sheets with satisfactory edge wicking even at the lowest size dosage (1 kg/t) while CTMP required a dosage of 4 kg/t to reach the same wick index. To achieve acceptable pressurised edge wicking values the most important parameter was found to be the density of the sheets. The kraft pulp sheets gave the lowest edge penetration while the high freeness CTMP sheets did not give satisfactory penetration resistant even at the highest size dosage. The edge wicking of lactic acid could be prevented by sizing with AKD only. Sheets made from mono sized sheets containing rosin size did not manage to avoid a large in-plane wetting of the board structure. Hence, dual sizing to improve the edge wicking of lactic acid is not necessary. The density was found not to be an important parameter in lactic acid edge wicking, all the pulps got equal edge wicking regardless of density. Retention above 1 kg/t AKD in sheets was enough to prevent penetration. Retention above 1.5 kg/t AKD in sheet did not improve the edge wicking any further. No significant difference in sizeability between unbleached and bleached CTMP was observed.

De senaste decennierna har en miniatyriseringstrend inom ingenjörsvetenskaperna blivit allt större. Komplexa maskiner eller processer skalas ner till en allt mindre skala. Det kan vara motorer som inte är större än 500 μm eller kemiska analyser som vanligtvis görs på en större laboratorieutrustning som nu går att utföra på en yta på ca 2x4 cm. En sådan utrustning som kan utföra kemiska analyser kallas ofta för ”Lab-on-a-Chip” (LoC) och innehåller kemiska kretsar som hanterar mikroflöden av analysvätskor. En del av dagens forskning för att ta fram nya LoC handlar om att möta ett behov av portabel, billig och snabb analysutrustning i utvecklingsländer. Dock finns ett problem med att få ut produkter på marknaden. De flesta LoC som presenteras i forskningsrapporter idag är tillverkade av polydimetylsiloxan (PDMS). Det är en elastomer som lämpar sig väl för småskalig prototypframställning, men är svår att producera i stor skala, dessutom krävs ofta extern utrustning för att vätskeflöde skall uppstå. Det finns även LoC i papper, vilkas porösa struktur möjliggör för spontan vätsketransport, wicking, utan extern utrustning. Dessa är billiga och har nått större framgång. Exempelvis är vanliga graviditetstest som går att köpa på apoteket ofta LoC i papper. Textiliers fukt- och vätskehantering är relevant för komfort, och för många beredningsprocesser. Exempelvis är wicking ett välstuderat område som det finns djup kunskap om i den textila sektorn. Denna kunskap kan utnyttjas för att skapa ett textilt LoC. Att använda textila tekniker innebär möjligheter att styra vätskeflödet med hjälp av garn med och utan wickingförmåga. Denna studie undersöker hur en vävs naturliga X-Y-system av varp- och väftgarner kan utnyttjas för att skapa en kontrollerad vätskestyrning, en textil kemisk krets. Arbetet har utgått från frågan om hur en väv kan konstrueras för att leda en vätska från ett varpgarn till ett väftgarn utan läckage i oönskad del av väven. Två olika garner valdes: ett monofilament av polyeten för de områden där vätskeledning ej var önskvärd och ett multifilament av Coolmax® polyester med god wickingförmåga där vätskan vara avsedd att transporteras. Tre parametrar testades; bindningen i de delar av väven som var avsedd för vätsketransport (önskad väg); bindningen där vätskan skulle övergå från ett varpgarn till ett väftgarn (vägskälet); och antalet wickande trådar (trådigheten). Åtta olika kombinationer avseende dessa parametrar testade. Samtliga parametrar hade signifikant inverkan på läckaget. Den konstruktion med minst läckage in i oönskad väg var den med bindning över två trådar i önskad väg, flotteringar i vägskälet och var tvåtrådig. Den framtagna vävens möjlighet att användas i en biosensor undersöktes genom ett försök att konstruera en elektrokemisk glukosmätare. Som elektroder valdes en silverbelagd polyamid. Vid preparering av elektroderna skedde en oväntad reaktion mellan det silverbelagda garnet och en av de ingående kemikalierna, prussian blue. Därför kunde ingen detektion av glukos ske. Det noterades även att den textila kemiska kretsens wickingförmåga försämrades då den utsattes för våta prepareringsprocesserna av elektroderna. Från experimentet med att konstruera en textil glukosmätare drogs slutsatsen att preparering av elektroderna bör ske innan invävning i den textila kemiska kretsen.

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