This dissertation aims to establish a mathematical model to predict the steady-state (stationary) motion of a nano-particle that is suppressed between two parallel moving objects. The main purpose of this study intends to find an appropriate means to reduce surface damage caused by moving nano-paricle. This study will show that, via the molecular dynamics (MD) analysis, the surface will result in different sizes of damaged layer and surface roughness when a nano-particle moves in a distinct way on it. Therefore, it has a significant value in the applications of high precision polishing and surface cleaning to identify the dominant factors in affecting the motion of nano-particle. The proposed model is to find the steady-state motion by meeting the conditions of force and torque balances on a moving nano-particle. Several hypotheses are suggested to derive the interaction force occurred at the interface between particle and each object. The hypothesis starts from the energy point of view. It is claimed that the potential and kinetic energies of object atoms will increase when nano-particle moves relative to the object. Because of the relative motion, some of the object atoms will be pushed or driven away, depending on the manner of motion. The increment of potential or kinetic energies is assumed to be proportional to the number of pushed or driven atoms. The increase of energy is supplied from the works done by the normal stress and shear stress at the interface of particle. The interaction at the front end of particle is very different from that at the rear end when particle rolls on object surface. There is a pushing action at the front end while a pulling action occurs at the rear end. The magnitudes of both actions are dominated and proportional to the adhesive strength between particle and object. The computer simulations show that the particle motion is mainly affected by the relative adhesive strength among particle and two objects. If the adhesive strength between particle and one object increase, the particle will increase the sliding speed relative to another object. On the other hand, if the adhesive strength between particle and one object is close to that of another object, the particle tends to have significant rolling motion relative to two objects. The suppressed loading between particle and objects has little effect on the qualitative trend of particle motion. The validity of proposed model is evaluated by the molecular dynamics simulation. It indicates that the predicted behaviors of proposed model are consistent with that from the analysis of molecular dynamics simulations.

Microwave processing, thermoplastic modification with reactive poly(arylene ether sulfone)s and improved flame retardance of di- and higher functionality epoxy resins were investigated. The influence of curing temperature and time on morphological development and fracture behavior was also studied. Arylamine functionalized poly(arylene ether sulfone)s of controlled molecular weight were synthesized as soluble, but reactive thermoplastic modifiers for aromatic amine cured epoxy resins. These materials were characterized via spectroscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), dilute solution viscosity, potentiometric titration of their end groups and model chain extension reactions. Thermoplastic modification of the epoxy networks was demonstrated to afford materials with improved fracture resistance. Two glass transition temperatures were detected in the modified network systems via DSC. Scanning electron microscopy further confirmed the development of a two phase morphology in modified systems and that it could be controlled from a dispersed thermoplastic in a continuous epoxy phase, to a phase inverted morphology as the modifier increased from approximately 15 to 30 weight percent. Improvements in adhesive strength to titanium and fracture toughness were also attributed to the utilization of reactively endcapped polysulfone modifiers and the highest values were obtained with the phase inverted morphology. / Ph. D.

"Polyelectrolyte multilayer (PEM) thin films prepared via the Layer-by-Layer (LbL) deposition technique are of special interest in this research. The purpose of this study is to replace current mechanical closure systems, based on hook-and-loop type fasteners (i.e. Velcro), with PEM thin film systems. The technique is simple, cheap, versatile and environmental friendly; as a consequence a variety of thin films can be easily fabricated. By proposing PEMs as non-mechanical and nanoscopic molecular closures, we aim to obtain hermetic sealing, good adhesive strength, and peel off ease. Atomic force microscopy (AFM) and colloidal probe techniques were used to characterize the morphology, roughness and adhesive properties of PEMs. AFM measurements were conducted in air, necessarily requiring careful control of ambient humidity. PEMs were formed by consecutive deposition of polyanions and polycations on a charged polyethylene terephthalate (PET) solid surface, the result of which was stable nanostructured films. By systemically varying the parameters of PEM build-up process: different combinations of polyelectrolytes, different numbers of bilayers (polyanion/polycation pairs), and miscellaneous types and concentrations of salts (NaCl, NaBr and NaF salts at 0.5 M and 1.0 M concentrations), the adhesion and morphology of PEMs were thoroughly investigated. The PEM thin films specifically investigated include poly(ethyleneimine) (PEI), poly(styrene sulfonate) (PSS), poly(allylamine hydrochloride) (PAH), poly(acrylic acid) (PAA), and poly(diallydimethylammonium chloride) (PDADMAC). Silica colloidal probes were utilized in the investigation, some of which were functionalized with COOH and/or coated with PEI-PSS. Silica colloidal probes were used in order to quantify interaction forces on the PEMs. A functionalized silica colloidal probe (a probe with COOH surface chemistry) and a silica colloidal probe coated with PEI-PSS were used to simulate PEM-PEM interactions. The results suggest that adhesion in the PEMs depend on the number of layers, the salt concentration and the salt type used during the build-up process, the environmental conditions where the adhesion force measurements were made, and the choice of probe. "

Es wurde das Verzinkungsverhalten von Baustahl beim Stückverzinken im technisch nutzbaren Bereich untersucht. Dazu wurde das Schichtwachstum der Zinküberzüge bei Verwendung konventioneller ZnPb-Schmelze anhand von Schichtdicken und Gefügeausbildungen in Ab-hängigkeit von den relevanten Parametern ermittelt. Weiterhin wurde der Einfluss des Was-serstoffs im Stahl auf die Schichtbildung beim Feuerverzinken eingeschätzt. Das Resultat ist eine umfassende Modellvorstellung der Schichtbildungsvorgänge beim Feuerverzinken von 435°C bis 620°C. Sie erklärt das Verzinkungsverhalten von Baustahl und trägt zum Verständnis vieler Phänomene beim Feuerverzinken bei. Weiterhin wurden Überzüge aus legierten Zinkschmelzen untersucht. Die Ergebnisse wurden hinsichtlich der Wirkung der einzelnen Legierungselemente in der Zinkschmelze interpretiert. Dem Anwender wird ein Leitfaden zur Verfügung gestellt, der Vor- und Nachteile der in der Praxis verfügbaren Zinkschmelzen beschreibt.

No description available.

Es wurde das Verzinkungsverhalten von Baustahl beim Stückverzinken im technisch nutzbaren Bereich untersucht. Dazu wurde das Schichtwachstum der Zinküberzüge bei Verwendung konventioneller ZnPb-Schmelze anhand von Schichtdicken und Gefügeausbildungen in Ab-hängigkeit von den relevanten Parametern ermittelt. Weiterhin wurde der Einfluss des Was-serstoffs im Stahl auf die Schichtbildung beim Feuerverzinken eingeschätzt. Das Resultat ist eine umfassende Modellvorstellung der Schichtbildungsvorgänge beim Feuerverzinken von 435°C bis 620°C. Sie erklärt das Verzinkungsverhalten von Baustahl und trägt zum Verständnis vieler Phänomene beim Feuerverzinken bei. Weiterhin wurden Überzüge aus legierten Zinkschmelzen untersucht. Die Ergebnisse wurden hinsichtlich der Wirkung der einzelnen Legierungselemente in der Zinkschmelze interpretiert. Dem Anwender wird ein Leitfaden zur Verfügung gestellt, der Vor- und Nachteile der in der Praxis verfügbaren Zinkschmelzen beschreibt.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-08-12T10:36:05Z No. of bitstreams: 2 Dissertação - Aline Crispim Canedo Girardi - 2016.pdf: 6052802 bytes, checksum: 19568ea8fd9027193ffed70b254b8bdc (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-12T14:17:29Z (GMT) No. of bitstreams: 2 Dissertação - Aline Crispim Canedo Girardi - 2016.pdf: 6052802 bytes, checksum: 19568ea8fd9027193ffed70b254b8bdc (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-08-12T14:17:29Z (GMT). No. of bitstreams: 2 Dissertação - Aline Crispim Canedo Girardi - 2016.pdf: 6052802 bytes, checksum: 19568ea8fd9027193ffed70b254b8bdc (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-05-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Although the use of CDW in the aggregate production is studied in Brazil for more than two decades, there are still gaps regarding their use in mortars. In this sense, the present study aims to evaluate mortar for rendering masonry produced with full replacement of natural sand by recycled aggregate, seeking to correlate the various properties and characteristics of aggregates and mortars with the performance of rendering with regard to the adhesive strength and absorption/water permeability. For the development of the research three types of aggregates were used (natural sand, mixed recycled ceramic and cement and cementitious recycled) in two particle sizes, passers-by screens 3 mm and 1.18 mm, which were widely characterized. With the data obtained in the characterization of aggregates, different traces were formulated for mortars, keeping fixed the content of total fine plasticizers. The mortars were evaluated on their consistency, bulk density, dimensional instability (shrinkage), water absorption, compressive and flexural strength. The renderings were applied on ceramic blocks, which were selected for initial water absorption rate ranges, avoiding the variability of results due to changes in the suction of the substrate. Two types of preparation of the base were performed, lime solution and roughcast, the latter was used only for the rendering that showed the best performance among those produced with recycled aggregates. As the main results, it was found that using a sieve with an opening of 1.18 mm is effective for reducing the content of fine aggregate, however, mortars and renderings produced with these aggregates showed unsatisfactory performance, falling short of results in materials with through 3 mm sieve. Mortars and rendering produced with recycled aggregate cement did not show compatible performance with the others, at the expense of the initial assumptions, which provided that this aggregate would exceed the aggregate mixed. It was also noticed that the recycled aggregates mixed ceramic and cementitious material, passers the sieve 3 mm, despite the high content of fine and high water absorption, resemble very to the natural aggregate with the same granulometry, when comparing the characteristics of mortars they have produced, mainly for resistance to compression. When assessing the rendering produced by these two aggregates, both are equivalent in the question of adhesive strength and showed no cracking. In general, it can be concluded that it is feasible the production of efficient rendering with complete replacement of natural sand for mixed recycled aggregates since the RCD origin and characteristics are known, Provided that limited the packing factor of grain , which directly influence the properties of mortars and renderings. / Apesar de a utilização de RCD na produção de agregado miúdo ser estudada no Brasil há mais de duas décadas, ainda não há correlações definidas entre as características dos agregados reciclados e o desempenho dos revestimentos, de forma a identificar as propriedades que deverão ser controladas no momento da escolha dos agregados que será incorporado às argamassas, independente do tipo de resíduo original. Nesse sentido, o presente trabalho visa determinar a viabilidade técnica da substituição total de agregado natural por agregado reciclado no preparo de argamassas de revestimento, buscando correlacionar as diversas propriedades e características dos agregados e das argamassas com o desempenho dos revestimentos, no que tange à resistência de aderência à tração e absorção/permeabilidade de água. Para o desenvolvimento da pesquisa utilizou-se três tipos de agregados (areia natural, reciclado misto de material cerâmico e cimentício e reciclado cimentício), em duas granulometrias, passantes pelas peneiras 3 mm e 1,18 mm, os quais foram amplamente caracterizados. As argamassas produzidas foram avaliadas quanto à consistência, densidade de massa, retração, absorção de água por imersão, resistência à compressão e resistência à tração. Os revestimentos foram aplicados sobre blocos cerâmicos, preparados com solução de cal ou chapisco, sendo este último apenas para o revestimento que apresentou o melhor desempenho dentre os produzidos com agregados reciclados. Como principais resultados, verificou-se que a utilização de peneira com abertura de 1,18 mm é eficiente para a redução do teor de finos dos agregados, entretanto, as argamassas e os revestimentos produzidos não apresentaram desempenho satisfatório, ficando aquém dos resultados obtidos com materiais passantes na peneira 3 mm. As argamassas e revestimentos contendo agregado reciclado cimentício não apresentaram desempenho compatível com as demais, em detrimento das suposições iniciais, que previam que esse agregado seria superior ao agregado misto. Também se percebeu que os agregados reciclados mistos de material cerâmico e cimentício, passantes na peneira 3 mm, apesar do alto teor de finos e da elevada absorção de água, assemelham-se muito ao agregado natural de mesma granulometria, quando comparadas as características das argamassas por estes produzidas, principalmente quanto à resistência à compressão. Quando se avaliam os revestimentos produzidos por esses dois agregados, ambos são equivalentes em questão de resistência de aderência à tração e não apresentaram nenhuma fissuração. Em linhas gerais, pode-se concluir que é viável a produção de revestimentos eficientes com substituição total da areia natural por agregados reciclados, desde que limitado o fator de empacotamento dos grãos, que influência diretamente nas propriedades das argamassas e revestimentos.

No description available.

Hot melt adhesives (HMA) are a class of adhesives that, unlike solvent-or waterborne counterparts, do not contain organic solvents or other carriers, and are produced and subsequently applied in a molten state. The main components of HMA are polymers, tackifying resins, and a plasticiser. HMA offer a more environmentally friendly option of adhesive materials.  This study was undertaken to investigate the performance of plasticisers based on renewable resources in HMA. Historically, mineral oil-based plasticisers have been used with great success in HMA formulations, offering a performance benchmark. This work selected suitable alternatives from renewable resources, ranging from fully renewable to fully conventional compositions. During the production stage, the compatibility of such plasticisers with the rest of the HMA formulation was studied while rheological methods were used to investigate the impact of different plasticisers on the properties of the final HMA. Adhesive properties were also assessed by loop tack and peel tests on polyethylene terephthalate (PET) and stainless steel (SS) substrates.   It was shown that some of the studied materials from renewable resources could offer a suitable component in the design of a biobased plasticiser, whose performance matched conventional plasticisers, while the ratio of the biobased fraction was up to 70 % and possibly even higher. The findings of this work show the potential of biobased alternatives in making HMA with a higher degree of sustainability. / Smältlim är en klass av lim som, till skillnad från lösningsmedels-eller vattenburna motsvarigheter, inte innehåller organiska lösningsmedel eller andra bärare, och som produceras och appliceras därefter i smält tillstånd. Huvudkomponenterna i HMA är polymerer, klibbgivande hartser och en mjukgörare. smältlim erbjuder ett mer miljövänligt alternativ för limmaterial. Denna studie genomfördes för att undersöka prestandan hos mjukgörare baserade på förnybara resurser i HMA. Historiskt har mineraloljebaserade mjukgörare använts med stor framgång i HMA-formuleringar, vilket ger ett prestandariktmärke. Lämpliga alternativ valdes ut från förnybara resurser, allt från helt förnybara till helt konventionella kompositioner. Under produktionsstadiet studerades kompatibiliteten av sådana mjukgörare med resten av smältlimsformuleringen medan reologiska metoder användes för att undersöka olika mjukgörares inverkan på egenskaperna hos det slutliga limmet. Vidhäftningsegenskaperna utvärderades också genom loop tack test och peel test på polyetylentereftalat (PET) och rostfritt stål (SS) substrat. Det visades att en del av de studerade materialen från förnybara resurser kunde erbjuda en lämplig komponent i designen av en biobaserad mjukgörare, vars prestanda matchade konventionella mjukgörare, medan förhållandet mellan den biobaserade fraktionen var upp till 70 % och möjligen ännu högre. Resultaten av detta arbete visar potentialen hos biobaserade alternativ för att göra HMA med en högre grad av hållbarhet.

To attain a sustainable development in the field of building materials, it is necessary to consider environmental, economic, and social aspects of the industrial production. This thesis addresses the first two aspects. Both theoretical and practical research were implemented in order to study the possibility to replace the commonly used RDPs, that are being used in the dry-mix mortar industry as a primary additive, with the industrially processed elastomer waste materials, such as recycled tire rubber. The review of the scientific literature processed within the theoretical research discloses the state of the art in the field of polymer modification of the mortar products and the effect of the commonly used modifiers and elastomer fillers on the performance of mortar and concrete products. The experimental research was implemented to study the possibility of the replacement of the RDPs for the elastomer fillers. The performance of fresh and hardened mortar containing various amounts of elastomer particles was studied. The results indicate, that the partial replacement could be feasible without worsening the performance of the product.