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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

How to take care of your rainwear, An evaluation of commercially available laundry and waterproofing agents and their effect on maintaining water-repellence.

DOEDENS, MARIEKEN January 2013 (has links)
Breathable water-repellent garments are common products on the outdoor market. There are many recommendations on how to wash and waterproof your garment in order to make sure that its water-repellence is cared for, but the advice given by different sources is inconsistent. Are expensive products really necessarily or are regular laundry products just as good? What waterproofing agents should one use in order to insure that the water-repellent layer is restored? Four different water-repellent wash-in products were tested on polyester and polyamide fabrics. Seven laundry products and two water-repellent wash-in products were tested on jackets with dendrimer based finishes and untreated polyamide fabrics. The results were evaluated by spray testing according to ISO EN 24920 and sessile drop tests. Not all wash-in products offer good water-repellence on polyamide and polyester fabrics. Two laundry detergents decreased the water-repellence of the jackets. The laundry detergents did not affect the function of wash-in waterproofing agents on the jackets. The water-repellence of one wash-in product was affected by the use of two different detergents on untreated fabric / Program: Textilingenjörsutbildningen
2

Micro and nano sized textile topography for improved water repellence

WETTERBORG, MALIN January 2014 (has links)
Water repellent fabrics with superhydrophobic properties have been constructed during this diploma work. First the fabrics were woven using six different weft yarns creating micro roughness and then a nanoparticle and surface energy lowering treatment was made. Contact angle measurements, contact angle hysteresis measurements, roll-off angle measurements and spray tests were made on the fabrics to investigate the hydrophobicity and water repellence. Also the durability was tested to examine the fastness of the treatments. It was found that the nanoparticles boosted the hydrophobicity of the hydrophobic treatments. Also by varying the size of textile filaments in yarns, the hydrophobicity of the material was affected. In this study, it was found how small textile parameters in the fabric could be changed to increase both durability and water repellence. / Program: Textilingenjörsutbildningen
3

Coating on viscose fabric with respect to environmental aspect

Ghosh, Asit, Mehmood Shah Nawaz, Muhammad January 2011 (has links)
Cotton as a dominating natural fibre imparts a major contribution in the whole textile market including natural and artificial fibres. The demand of this cellulosic fibre is increasing rapidly day by day, on the other hand supply cannot fulfill its demand, and as a result price goes higher in world market. Now people are looking for alternatives to cotton in different applications. Viscose as cellulosic origin, the cheapest of all cellulosic fibres could be the best alternative. Viscose fibre exhibits some similar properties compared to cotton except its poor wet strength. In this thesis work different chemical finishes were applied to improve the wet strength of viscose fabric. For this purpose water repellent and soil release finishes were applied. Both water repellent and soil release finishes helped in reducing the molecular barrier around the individual fibres that lowered the surface tension of the fibre. It reduces the absorbency of viscose fibre hence leads to higher wet strength. Water repellent finish was applied alone as well as in combination with soil release finish. It was seen that viscose fibre exhibited better wet strength after applying water repellent and soil release finishes on it. This improved property of viscose could replace the cotton fibre in certain applications like bed linen. / Program: Magisterutbildning i textilteknologi
4

Tratamento superficial dos agregados reciclados de RCD com hidrofugantes. / Surface treatment of CDW recycled aggregates with water-repellents.

Santos, Winnie Franco 04 April 2016 (has links)
A proposta busca reduzir a absorção de água dos agregados reciclados de Resíduos de Construção e Demolição (RCD), através do tratamento de sua superfície com hidrofugante, de maneira que estes não aumentem o consumo de água tampouco reduzam a resistência mecânica. Os agregados reciclados de RCD foram caracterizados quanto à granulometria, morfologia, porosidade, ângulo de contato aparente, absorção de água, análise de imagem e rugosidade superficial. Em seguida, os mesmos foram tratados superficialmente com dois tipos de hidrofugante: solução de silano e parafina. Todos os tratamentos permitiram reduzir a absorção de água dos agregados reciclados de RCD. O tratamento por imersão foi aquele que permitiu obter os melhores resultados e a menor variabilidade entre as técnicas. Os tratamentos hidrofugam a superfície, apesar da parafina apresentar maior molhabilidade. O tratamento com parafina apresentou, em termos de absorção de água, resultados inferiores e menos variáveis que o silano. Os parâmetros de rugosidade constataram que, ambos os materiais perdem seu perfil topográfico original quando tratados com parafina. Os diferentes agregados reciclados com cada hidrofugante foram aplicados em materiais cimentícios analisados no estado fresco e no estado endurecido. Os tratamentos reduziram a absorção e o consumo de água de mistura, porém afetaram negativamente as propriedades mecânicas, devido nova interface gerada (no caso específica de parafina) e falta de molhabilidade nas superfícies. / The proposal aims to reduce the water absorption of the Construction and Demolition Waste (CDW) recycled aggregates through hydrophobic surface treatment, so that these do not increase the concretes water consumption (nor reduce de mechanical strength). The CDW recycled aggregates were characterized regarding granulometry, morphology, porosity, apparent contact angle, water absorption, image analysis and surface roughness. Then they had their surface treated with two types of water-repellent: silane solution and paraffin. All treatments have reduced water absorption of the CDW recycled aggregate. Immersion treatment was the one that allowed the best results and the lowest variability between techniques. The treatments repel water on surface, despite the paraffin presenting better wettability. Paraffin treatment showed, in terms of water absorption, lower and less variable results than silane did. Roughness parameters found that both materials lose their topographic profile when treating with paraffin. The different recycled aggregates with each repellent were applied in cementitious materials analyzed in fresh and hardened state. The treatments reduced absorption and mixing consumption of water in the mixing, but adversely affect mechanical properties due to the new interface created (paraffin wax in special) and the lack of wettability on surfaces.
5

Traitement hydrofuge dans la masse par l'incorporation de silicone (polymère à base de silicium)/ Water repellent cement based materials by incorporation Si-based additives

Spaeth, Valérie R. M. 10 March 2011 (has links)
Les façades des nouveaux bâtiments et des bâtiments existants sont altérées par la pénétration de l'eau. Afin de protéger les bâtiments et surfaces exposées aux intempéries, des traitements contenant des agents hydrophobes doivent être appliqués. Les traitements utilisés à l’heure actuelle sont des traitements de surface qui se dégradent au cours du temps. L'agent hydrophobe, présent en surface, est soumis à des conditions très rudes telles que des rayonnements ultraviolets, de grandes variations de température, de l'abrasion ..., qui réduisent l’efficacité et la durabilité des traitements. La plupart des traitements aujourd'hui disponibles, fournisse une barrière efficace au passage de l’eau à court terme, mais doivent donc être réappliqués régulièrement. Le projet de recherche, présenté ici, traite de la mise en place d'un traitement de masse de matériaux cimentaires utilisés dans la protection de structures (joints, crépi ...). Ce traitement devrait offrir une protection à long terme, mais ne devrait pas modifier de manière significative les propriétés mécaniques des matériaux. Les avantages d'un traitement de masse sont évidents. Seule une petite partie de l'agent hydrophobe est exposée et dégradée par les conditions climatiques et l'abrasion de surface ne porte pas atteinte à l'intégrité du traitement. Une étude fondamentale a été menée afin d'étudier l'influence de l'incorporation d´agents à base de silicium sur les processus d'hydratation des ciments Portland et de comprendre leur mode d'action. Deux agents (alpha,omega dihydroxypolydimethylsiloxane et n-octyltriethoxysilane) et deux ciments Portland (ordinaire et blanc CEM I 42,5N) ont été choisis et étudiés. Trois modes d´introduction (liquides purs, émulsions et granules) ont été mis en œuvre et comparés. Le but est de déterminer les meilleures conditions pour obtenir un traitement efficace et durable tout en préservant les propriétés mécaniques. Les résultats d'absorption d'eau par capillarité et de perméabilité à la vapeur d’eau sont prometteurs et les essais mécaniques sur mortiers n’ont pas montré de diminutions significatives des résistances mécaniques. La microstructure et la progression de l'hydratation des matrices cimentaires adjuvantées et de référence, ont été caractérisées par calorimétrie à conduction, par calorimétrie différentielle à balayage couplée à la thermogravimétrie, par spectroscopie infra-rouge, par diffraction des rayons X, par porosimétrie au mercure, et par microscopie électronique à balayage. La durabilité des matériaux adjuvantés a été étudiée afin de montrer la pertinence des traitements ainsi que l'évaluation de la progression de l'hydratation. Les performances hydrofuges ainsi que l’évolution de la microstructure, à l’issue des différents vieillissements artificiels et naturels, ont été déterminées. Les mortiers mis en œuvre ont été soumis à des vieillissements artificiels simulant des conditions proches de celles rencontrées en pratique (tels que des cycles rayonnements UV, pluie, sel, gel/dégel…). Une amélioration de la durabilité des mortiers adjuvantés a été observée. Les résultats sont très encourageants et confirment l'intérêt d’un tel traitement dans la masse. /Protection of cement-based materials means above all, moisture protection because water is primarily responsible for inducing damaging physical and chemical processes in building materials. In most cases, water repellents are applied either directly during the construction or insulation process; or as a post-treatment of the exposed surfaces in order to protect the buildings from further decay. A new way is to develop a bulk treatment for cement-based materials which should provide a long term protection without modifying the mechanical properties of the cementitious materials. The advantages of a bulk treatment are obvious i.e. only a small part of the hydrophobic agent is exposed and degraded by the UV. In addition, surface abrasion does not affect the integrity of the treatment. A fundamental study was initiated to investigate the influence of the incorporation of two active silicon-based agents (already used as post-building treatments) on the hydration processes of Portland cements and to understand the involved mechanisms of interaction. Two agents (alpha,omega dihydroxypolydimethylsiloxane and n-octyltriethoxysilane) and two Portland cements (Ordinary and White Portland Cement CEM I 42,5N) were chosen and studied. Three incorporation modes (pure liquids, water emulsions and granules) were investigated. The effects of the three modes were compared. The aim was to determine the best conditions for an efficient and sustainable treatment preserving the mechanical properties of the materials. The results of capillary water penetration and water vapor permeability are promising and are not accompanied by a significant decrease of the mechanical performances The microstructure and progression of hydration of admixtured cement pastes were characterized by conduction calorimetry, differential scanning calorimetry, thermo-gravimetry, infra-red spectroscopy, X-ray diffraction, mercury intrusion porosimetry, and scanning electron microscopy. In addition, the durability of water-repellent additives and of the admixtured cement was studied in order to show the relevance of the treatments as well as the assessment of the progression of hydration and the type of products that were developed. Mortar specimens were submitted to artificial ageing cycles such as freeze-thaw cycles, ultraviolet cycles and rain-sun cycles. The general trend is an improvement of the durability of admixtured mortars. The results are very encouraging and confirm the interest of the bulk mortar treatment.
6

Elaboration de revêtements hybrides par le procédé sol-gel pour conférer de nouvelles fonctions à des matériaux textiles / Elaboration of hybrid coatings by sol-gel method for functionalization of textile materials

Boukhriss, Aicha 03 November 2015 (has links)
Ce travail de recherche consiste à proposer une fonctionnalisation des surfaces textiles par le procédé sol-gel à partir d’alcoxysilanes. L‘objectif est de conférer aux textiles des propriétés hydrofuges, ignifuges et fluorescentes. La première partie de notre étude traite dans un premier temps les paramètres de synthèse des sols et leur application sur différentes étoffes textiles. Ensuite, nous nous sommes intéressés à la synthèse des sols avec des alcoxydes de silicium permettant d’avoir des propriétés hydrofuges. Par la suite, les propriétés d’adsorption et de non mouillabilité des textiles traités ont été déterminées selon le standard AATCC- 22 et celles mécaniques selon la norme ISO 13934. Nous avons également étudié la stabilité thermique par des analyses ATG et les propriétés de non mouillabilité de ces textiles en fonction de leur photovieillissement accéléré. Dans un deuxième temps et dans l’optique de développer des textiles ignifuges, nous avons montré que l’immobilisation des LIs à la surface des textiles peut être réalisée par le procédé sol-gel. Pour ce faire nous avons tout d’abord synthétisé des liquides ioniques à partir d’un alcoxyde de silicium halogéné. Le sel obtenu est ensuite greffé sur des matrices textiles par le procédé sol- gel.Enfin, la dernière partie de l’étude consiste en la synthèse de fluorophores organiques par un procédé utilisant le couplage de type Heck. Leurs propriétés de photoluminescence ont été étudiées. Nous avons ainsi pu les greffer sur des surfaces pour développer des traceurs textiles fluorescents et des sondes pH fluorescentes. / This work consists to provide a functionalization of textile surfaces by the sol-gel process using alcoxysilanes. The final aim is to impart water repellent, flame retardant and fluorescent features to textile surfaces. Firstly, the effects of synthesis parameters such as the concentration of the alcoxysilanes and the impregnation time of the fabrics in the solution (sol) prepared have been thoroughly investigated. Then, we have prepared a silica modified sol which is expected to induce a water repellent feature to textile. To investigate the water repellency under practical conditions, the common “rain test” was used according to AATCC test method 22-2005 also mechanical properties of treated un untreated textile was studied according to ISO 13934. Furthermore, thermal properties of sol-gel modified textiles were investigated and their water repellency abilities were assessed and compared after photo ageing upon UV irradiations.Secondly, we have showed that the immobilization of ionic liquids onto the surface of textile fabrics can be achieved by the sol-gel process, which is of a growing interest due to its simplicity and flexibility. For this aim, two ionic liquids were synthesized using halogenated alkoxysilane, and then grafted onto the cotton fabrics by sol- gel process .The functionalized cotton fabrics exhibit good water repellency and flame stability. Finally, a fluorophores bearing phenolic hydroxyl and pyridinium end groups have been synthesized and grafted into cellulosic fiber by sol -gel process. This fluorophores have been firstly synthesized by double Heck couplings, and then we have studied their photo physical behavior as function of their concentration both in ethanol and in the textile. We have also grafted the fluorophores in cellulosic textile by sol gel method to have fluorescent and PH-sensitive properties.
7

Tratamento superficial dos agregados reciclados de RCD com hidrofugantes. / Surface treatment of CDW recycled aggregates with water-repellents.

Winnie Franco Santos 04 April 2016 (has links)
A proposta busca reduzir a absorção de água dos agregados reciclados de Resíduos de Construção e Demolição (RCD), através do tratamento de sua superfície com hidrofugante, de maneira que estes não aumentem o consumo de água tampouco reduzam a resistência mecânica. Os agregados reciclados de RCD foram caracterizados quanto à granulometria, morfologia, porosidade, ângulo de contato aparente, absorção de água, análise de imagem e rugosidade superficial. Em seguida, os mesmos foram tratados superficialmente com dois tipos de hidrofugante: solução de silano e parafina. Todos os tratamentos permitiram reduzir a absorção de água dos agregados reciclados de RCD. O tratamento por imersão foi aquele que permitiu obter os melhores resultados e a menor variabilidade entre as técnicas. Os tratamentos hidrofugam a superfície, apesar da parafina apresentar maior molhabilidade. O tratamento com parafina apresentou, em termos de absorção de água, resultados inferiores e menos variáveis que o silano. Os parâmetros de rugosidade constataram que, ambos os materiais perdem seu perfil topográfico original quando tratados com parafina. Os diferentes agregados reciclados com cada hidrofugante foram aplicados em materiais cimentícios analisados no estado fresco e no estado endurecido. Os tratamentos reduziram a absorção e o consumo de água de mistura, porém afetaram negativamente as propriedades mecânicas, devido nova interface gerada (no caso específica de parafina) e falta de molhabilidade nas superfícies. / The proposal aims to reduce the water absorption of the Construction and Demolition Waste (CDW) recycled aggregates through hydrophobic surface treatment, so that these do not increase the concretes water consumption (nor reduce de mechanical strength). The CDW recycled aggregates were characterized regarding granulometry, morphology, porosity, apparent contact angle, water absorption, image analysis and surface roughness. Then they had their surface treated with two types of water-repellent: silane solution and paraffin. All treatments have reduced water absorption of the CDW recycled aggregate. Immersion treatment was the one that allowed the best results and the lowest variability between techniques. The treatments repel water on surface, despite the paraffin presenting better wettability. Paraffin treatment showed, in terms of water absorption, lower and less variable results than silane did. Roughness parameters found that both materials lose their topographic profile when treating with paraffin. The different recycled aggregates with each repellent were applied in cementitious materials analyzed in fresh and hardened state. The treatments reduced absorption and mixing consumption of water in the mixing, but adversely affect mechanical properties due to the new interface created (paraffin wax in special) and the lack of wettability on surfaces.
8

Post-Wildfire Debris Flows: Mapping and Analysis of Risk Factors in Western North America / Jordskred till följd av skogsbränder: kartläggning och analys av riskfaktorer i västra Nordamerika

Tuinstra, Annejet January 2021 (has links)
Climate change is leading to in an increase in frequency and severity of wildfires, which in turn can result in the formation of runoff-initiated post-wildfire debris flows. This type of debris flows is, like most debris flows, triggered by heavy precipitation events. Debris flows have the potential to cause much damage, and therefore it is important to analyse when and where the risk of these flows exists. This study aims to identify shared characteristics of basins that experienced post-wildfire debris flows in order to improve future risk analyses regarding such flows. These characteristics were studied through the analysis of 42 basins in 10 burned areas across western North America, which experienced a total of 67 post-wildfire debris flows between 2000 and 2018. Literature research and existing databases revealed the bedrock, soil texture and the timing of the flows compared to the wildfires. Spatial analysis using ArcMap allowed for the analysis of the burn severity of the basins, the hypsometry of the basins, and the mean slope of the basins. Analysis of these characteristics revealed the importance of the hypsometric integral, the soil texture, and the mean slope angle of the basins. In general, the hypsometric integral tends to fall between 0.50 and 0.60 and only soils with a coarse texture were identified for the basins. The mean slope angle of the basins is commonly between 25-30o, with a wider range of slopes being able to generate debris flows shortly after the fire. If multiple basins in a small area are burned, those with steeper slope angles have a higher potential to generate debris flows, while basins with steeper slopes do not have a higher risk on large regional scales. In order to generate post-wildfire debris flows the basin also needs to be burned at a large extent at low to medium severity, resulting in an extensive and strong water-repellent layer required to generate the runoff that is needed to generate a debris flow. Seasonal wetting during winters and drying of the soil during summers can reduce or enhance runoff respectively as well. As a result, post-wildfire debris flows occur mostly during the late summer months shortly after a wildfire when precipitation is increasing through summer storms, or a year later when the soil is dried and primed during the summer followed by such a summer storm. Fires during winter and thus outside the traditional wildfire season can lead to post-wildfire debris flows during winter as well due to the strength of the fresh water-repellent layer. Climate change which will lead to more fires during late autumn and winter months can thereby result in post-wildfire debris flows during winter, rather than only during the summer months following wildfires in the traditional fire season. / Jordskred uppstår när en sammanhängande jordmassa kommer i snabb rörelse. Det är en typ av naturolyckor som kan skada både infrastruktur och människor. Sannolikheten att ett jordskred inträffar ökar efter skogsbränder. Samtidigt kan klimatförändringar leda till en ökning av skogsbränder vilket i sin tur kan leda till en ökad risk för jordskred i framtiden. Syftet med det här projektet är att bidra till bedömningen av risken av jordskred till följd av skogsbänder i västra Nordamerika och att identifiera andra områden som också har en stor risk att drabbs av skred efter skogsbränder genom att identifiera riskfaktorer. Under projektets gång skapades en databas med områden där jordskred inträffade efter skogsbränder i västra Nordamerika. Den vetenskapliga litteraturen visade några egenskaper av skred och områdena, t.ex. när branden och skredet hände, vilken berggrund finns i området och texturen av jordarten i området. Dessutom användandes GIS (Geographical Information System) med satellitbilder och DEM (Digital Elevation models), som visade information om brandskador samt de geomorfologiska karaktärerna av områden. Resultaten visade att formationen av jordskred kräver omfattande låga till måttliga brandskador som resulterar i ett starkt vattenavvisande jordlager. Detta jordlager minskar infiltrationskapaciteten av jorden och resulterar i mer ytavrinning vilket orsakar skred till följd av brand. Även en grov textur av jordlagret är viktig eftersom den också bidrar till ett starkt vattenavvisande jordlager. Dessutom kan askpartiklar bli fångade in i stora porer i jord med en grov textur vilket minskar infiltrationskapaciteten och ökar ytavrinningen. Det finns alltså två krav för att ett jordskred ska inträffa efter en skogsbrand: i) omfattande låga-måttliga brandskador, och ii) en grov textur av jorden. Vidare finns det några ytterligare egenskaper som ökar risken för skred efter skogsbränder om de två kraven är uppfyllda. Den hypsometriska integralen (ett sätt att uttrycka hypsometrin av en dal) ligger oftast mellan 0.50-0.60 vilket är normal för en geomorfologiskt sett mogna område. Dessutom hade de flesta områdena i projektet en medellutning mellan 25o och 30o. Dock fanns det även tillfällen där värdena låg utanför dessa intervaller. Därför kan dessa värden i sig inte användas som riskfaktorer, utan borde de även kombineras med de övriga egenskaperna som beskrivs i den här undersökningen. Det är också relevant att veta när jordskred inträffar till följd av skogsbränder. Resultaten visade att skred kan hända strax efter skogsbränder i slutet av sommaren när det finns kraftigt regn. Det är då som det vattenavvisande jordlagret är som starkast. Det vattenavvisande lagret minskar i styrkan under året, men det är också möjligt att det inträffar ett jordskred under sommaren året efter en skogsbrand. Då är jorden torr i slutet av sommaren när kraftigt regn inträffar efter torra månader. Torr jorden bidrar även till en minskad infiltrationskapacitet. Regn i vinter gör jorden blöt vilket ökar infiltrationskapaciteten av jorden. Dessutom sker det även skogsbränder utanför den traditionella skogsbrandsäsongen nuförtiden, t.ex. tidigt i vintern. I så fall kan jordskred också inträffa under samma vinter strax efter skogsbranden, därför att det vattenavvisande jordlagret som skapas i branden fortfarande är starkt då. Som nämnts tidigare finns det en riskprofil som kan användas för att identifiera områden som har en hög risk för jordskred efter skogsbränder, men möjligheten att ett jordskred inträffar under vintern istället för (slutet av) sommaren bör även iakttas. Risken växer nämligen i samband med klimatförändringar som leder till mer skogsbränder; inte bara under sommaren, utan även under vintern.
9

Supercritical carbon dioxide as a green media for simultaneous dyeing and functionalisation : A study on disperse dyeing and silicone functionalisation for water repellency of polyester fabric

Schulz, Anika January 2019 (has links)
Textile processing methods such as conventional exhaustion dyeing, pre-treatments and printing consume high amounts of water and use partly toxic and hazardous chemicals which are non-degradable. These chemicals (e.g. excess amount of dye, additives and catalysts) remain partially in the waste-water which is drained out and ends up polluting the environment. The supercritical carbon dioxide dyeing technology presents an eco-friendly and water-free method with reduced use of chemicals and energy. The benefits of such technology are currently not overcoming the relative high investment costs which impede its full implementation into the textile industry. This study presents an approach to extent the application of the eco-friendly supercritical carbon dioxide technology. It combines the well-studied supercritical carbon dioxide dyeing process for polyester with the functionalisation process to obtain water repellent surface properties. As water repellent (substance) environmentally benign silicones are used. Results showed that the simultaneous dyeing and functionalisation process was feasible assessed by the compatibility of the dye and silicone in the system. Silicone and dye did not interfere in each other’s functionality (colour strength and water contact angle). Further the process temperature and silicone molecular weight showed no influence on the colour strength of the fabric whereas the water contact angle (water repellence) increased with increasing temperature. The resulting polyester fabric showed acceptable colour strength yet did not obtain sufficient water repellent properties despite the increase in water contact angle of the treated samples to the untreated reference sample. The poor water repellence is suggested to be caused by the hydrophobic functional groups of the silicones oriented towards each other rather than toward the outer fabric surface. Overall the thesis is promoting research which combines eco-friendly technologies including environmental benign chemicals for the textile industry. Silicones are widely used in textile processing not only as water repellents, but also as anti-foaming agents, lubricants and softeners. Therefore a water-free and eco-friendly application method can benefit a wide range of finishing processes.
10

Computer Modelling of the Influence of Surface Topography on Water Repellency and a Study on Hydrophobic Paper Surfaces with Partly Controlled Roughness / Datamodellering av yttopografins inverkan på vattenavvisning och en studie på hydrofoba pappersytor med delvis kontrollerad råhet

Werner, Oskar January 2003 (has links)
<p>A computer model based on minimization of the free energy, capable to predict contact angles and spreading transitions between Wenzel and Cassie mode for drops placed on surfaces with different topography were implemented in matlab. Simulations were compared with experiments documented in the literature. These showed that reported transitions between Cassie and Wenzel mode can be explained by minimization of the free energy. In this report, a study on the possibility of constructing water repellent paper surfaces with a combination of treatment with octadecyltrichlorosilane and topography changes, is included.</p>

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