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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.
81

Preparação de nanopartículas funcionalizadas do tipo casca-núcleo à base de poliestireno e poli(acrilato de butila) para processamento baroplástico / Functionalized poly(butyacrylate-co-styrene) core-shell nanoparticles for baroplastic processing

Fernanda Furtado de Melo Albino 09 September 2009 (has links)
Copolímeros casca-núcleo de poli(acrilato de butila) (núcleo) e poliestireno (casca) foram sintetizados por meio de polimerização em emulsão, conduzida em duas etapas. A adição de ácido itacônico como monômero funcional na polimerização do núcleo foi realizada para verificar seu efeito sobre suas propriedades mecânicas e de processamento. Os copolímeros foram caracterizados por espalhamento dinâmico de luz (DLS), microscopia eletrônica de transmissão (MET), cromatografia de exclusão por tamanho (SEC), espectrometria na região do infravermelho (FTIR) e calorimetria diferencial por varredura (DSC). A incorporação do monômero funcional foi confirmada por DSC e quantificada por titulação. A proporção de poli(acrilato de butila) e poliestireno influenciou diretamente o processamento e as propriedades mecânicas do polímero. Os copolímeros com teores de poliestireno acima de 50% foram processados por compressão e extrusão a temperatura ambiente, apresentando comportamento baroplástico. A presença do monômero funcional não alterou o processamento do polímero e melhorou significativamente sua resistência à tração, aumentando sua tenacidade / Core shell copolymers of poly(butyl acrylate) cores and polystyrene shells were synthesized in a two-stage emulsion polymerization. The addition of itaconic acid as functional monomer in the core polymerization was carried out in order to study its influence on polymer processing and mechanical properties. The copolymers were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The functional monomer incorporation was confirmed by DSC and quantified by titration. The poly(butyl acrylate) and polystyrene proportions had a direct influence on the polymer processing and mechanical properties. Copolymers with polystyrene contents higher than 50% presented baroplastic behavior and they could be processed at room temperature by compression molding and extrusion. The presence of itaconic acid did not affect polymer processing and significantly improved tensile resistance, increasing its toughness
82

Caractérisation structurale d'hydroxydes doubles lamellaires contenant des anions oxométallates (Mo,W) ou acrylate intercalés

Vaysse, Christophe 14 December 2001 (has links) (PDF)
De nouveaux hydroxydes doubles lamellaires (LDHs) contenant des entités oxométallates (Mo, W) intercalées ont été préparés et caractérisés par diffraction des rayons X (DRX), analyse chimique, spectroscopie infrarouge (IR) et EXAFS. Dans les deux cas, des anions M2072- (M = Mo, W) constitués de deux tétraèdres à sommet commun, sont intercalés. L'évolution structurale des phases LDHs contenant des ions oxométallates libres dans l'espace interfeuillet, traitées thermiquement jusqu'à 800'C, a été étudiée. Il a ainsi été montré que les anions oxométallates se greffent à deux feuillets adjacents au voisinage de 200'C. Le comportement thermique de phases contenant des anions carbonate intercalés a également été appréhendé par DRX in et ex situ, spectroscopie IR, analyse chimique et thermogravimétrie couplée à la spectrométrie de masse. Il a été mis en évidence un mono-greffage des anions carbonate aux feuillets. L'intercalation et l'oligomérisation d'anions acrylate dans les LDHs ont également été réalisées. Des différences, de comportement sont observées selon la nature de l'ion substituant du nickel (Fe, Co ou Mn) dans les feuillets. Dans le cas du fer, la phase contenant les monomères intercalés a pu être isolée et caractérisée, alors que dans le cas du cobalt et du manganèse, une polymérisation spontanée, simultanément à l'intercalation dans la matrice, a été observées. Les macromolécules polymérisées in situ ont été extraites par échange anionique, dérivatisées en poly(acrylate de méthyle) et analysées par chromatographie d'exclusion stérique.
83

Structures et propriétés rhéologiques d'hydrogels à dynamique contrôlée obtenus par l'auto-assemblage de copolymères à blocs amphiphiles

Charbonneau, Céline 19 October 2012 (has links) (PDF)
Les copolymères à blocs amphiphiles sont des macromolécules composées d'au moins un bloc hydrophile lié chimiquement à un ou plusieurs blocs hydrophobes. En milieu aqueux, ils s'auto-associent pour former des micelles dont les cœurs constitués des blocs hydrophobes sont protégés de l'eau par une couronne constituée des blocs hydrophiles hydratés. La majorité des copolymères à blocs amphiphiles génèrent dans l'eau des micelles " gelées " ne présentant aucun échange de chaînes entre elles. Ceci vient du fait que l'énergie nécessaire pour extraire un bloc hydrophobe du cœur des objets est beaucoup trop importante. Par conséquent, les caractéristiques des micelles sont plus contrôlées cinétiquement que thermodynamiquement. Pour diminuer cette énergie nous avons incorporé des unités hydrophile acide acrylique (AA) dans le bloc hydrophobe de poly(acrylate de n-butyle) (PnBA). L'incorporation de 50% molaire d'unités AA dans le bloc hydrophobe conduit à la formation d'agrégats pH-sensibles dans le cas du dibloc PAA-b-P(AA0.5-stat-nBA0.5) comme montré dans une étude antérieure. Cette thèse a consisté en une analyse quantitative de la dynamique d'auto-association de copolymères dibloc et tribloc amphiphiles à base d'acrylate de n-butyle et d'acide acrylique dont les blocs hydrophobes contiennent 50% d'unités hydrophiles réparties de manière statistique. Les copolymères à blocs ont été synthétisés par polymérisation radicalaire contrôlée par ATRP. L'influence de la concentration, du pH, de la température et de la force ionique sur la structure et les propriétés mécaniques des systèmes auto-assemblés a été systématiquement étudiée. Par diffusion statique de la lumière nous avons montré la présence d'une concentration d'agrégation critique (CAC) au-dessus de laquelle, des micelles de type étoile (dibloc) ou fleur (tribloc) sont formées par auto-association des blocs hydrophobes. A plus fortes concentrations, des interactions répulsives de type volume exclu apparaissent entre les micelles étoiles. Pour les micelles fleurs, à l'inverse des interactions attractives conduisent au pontage des fleurs jusqu'à l'obtention de réseaux tri-dimensionnels au-dessus de la concentration de percolation. Une attraction trop importante entre les fleurs peut même conduire à une séparation de phase à forte force ionique et bas pH. En diffusion dynamique de la lumière, nous avons montré que la formation des réseaux s'accompagnait de l'apparition d'un mode lent dont l'origine a été expliquée par un mouvement balistique d'hétérogénéités relaxées dans les systèmes. La vitesse de relaxation de ces hétérogénéités s'avèrent être dépendantes des propriétés mécaniques des hydrogels. La formation des réseaux et la dynamique d'échange des chaînes ont été étudiées par rhéologie. La viscosité augmente régulièrement avec la concentration jusqu'à la concentration de percolation où une augmentation brusque de la viscosité se produit et un temps de relaxation apparaît. Le temps de vie des ponts a été finement contrôlé et modulé sur plusieurs décades par modification du pH, de la température et de la force ionique. La formation in-situ des hydrogels nous a permis de mettre en évidence un phénomène de vieillissement des réseaux après leur formation avant d'atteindre un état stationnaire. Ce phénomène s'est traduit par une augmentation du temps de relaxation au cours du temps avant d'atteindre une valeur plateau. Ceci nous a également permis de comprendre pourquoi il était possible de générer des réseaux homogènes, par vieillissement, possédant une dynamique extrêmement lente voir nulle.
84

Preparation and long-term performance of poly(ethylene-co-butyl acrylate) nanocomposites and polyethylene

Nawaz, Sohail January 2012 (has links)
The current study discusses the preparation and long-term performance of polymer composites used for various purposes under different ageing conditions. The first part deals with the preparation and characterization of polymer nanocomposites based on poly(ethylene-co-butyl acrylate) (EBA–13 and EBA–28 with 13 and 28 wt % butyl acrylate, respectively) and 2–12 wt % (0.5–3 vol %) of aluminum oxide nanoparticles (two types with different specific surface areas and different hydroxyl-group concentrations; uncoated and coated with, respectively, octyltriethoxysilane and aminopropyltriethoxysilane). The nanocomposite with EBA–13 showed better overall nanoparticle dispersion while EBA–28 resulted in poor dispersion, probably due to insufficiently high shear forces acting during extrusion mixing which were unable to break down nanoparticle agglomerates. The activity of hindered phenolic antioxidant (0.2 wt%) in all EBA nanocomposites was assessed by determining the oxidation induction time using DSC. The composites containing uncoated aluminium oxide nanoparticles showed a much shorter initial OIT than the pristine polymer with the same initial concentration of antioxidant, indicating adsorption of antioxidant onto the nanoparticle surfaces. Composites containing coated nanoparticles showed a significantly smaller decrease in the initial OIT, suggesting the replacement of hydroxyl groups with organic silane tails, decreasing the concentration of available adsorption sites on the nanoparticle surfaces. The decrease in OIT with increasing ageing time in dry air at 90 °C of the nanocomposites was slower than that of the unfilled pristine polymer, suggesting a slow release of antioxidant from adsorption sites. The EBA nanocomposites exposed to liquid water at 90°C showed faster decrease of OIT than samples exposed to dry or humid air. The migration rate of antioxidant was controlled by the boundary conditions in the case of ageing in humid air and liquid water. The antioxidant diffusivity was lower for the composites containing uncoated ND than for the composites containing ND coated with octyltriethoxysilane or aminopropyltriethoxysilane. The migration and chemical consumption of deltamethrin DM, (synthetic pyrethroid) and synergist piperonyl butoxide from molded polyethylene sheets was also studied. Deltamethrin and piperonyl butoxide are often used for food  storage and insect control purposes. DM showed no signs of crystallization and remained in a liquid state after being cooled to room temperature. Exposure of polyethylene compound sheets to liquid water (at 80 &amp; 95 °C), caused degradation and hydrolysis of the ester bond in the DM, present in the prepared material, and generated species containing hydroxyl groups. Liquid chromatography and infrared spectroscopy showed a significant migration of the active species in liquid water, whereas in air at 80 °C (60 and 80 %RH) the loss of DM and PBO was negligible over 30 days. The long-term performance of medium-density polyethylene stabilized with six different phenolic antioxidants (0.1 wt%) in aqueous chlorinated media at 70 °C was studied. The results were compared with data for previously studied solutions of antioxidants in squalane (a liquid, low molar mass analogue of polyethylene). A linear relationship was established between the time to reach antioxidant depletion in polyethylene tape samples and the time in squalane samples. Infrared spectroscopy and scanning electron microscopy of drawn samples revealed the onset of surface oxidation and surface embrittlement in tape samples exposed beyond the time for antioxidant depletion. / <p>QC 20121109</p> / Cable insulation materials / Loss of deltamethrin and pipronyl butoxide from polyethylene / long-term performance of polyethylene in chlorine dioxide water
85

Amphiphile Polyurethan-Makromere als Emulgatoren und Comonomere für die heterophasige Polymerisation hydrophober Monomere

Jahny, Karsten 14 May 2002 (has links) (PDF)
Die Arbeit beschreibt die Synthese und Charakterisierung von amphiphilen Polyurethanen mit Emulgatoreigenschaften für die Polymerisation hydrophober Monomere in wässriger Phase. Der Emulgator wurde mit kolloid- und polymerchemischen Methoden hinsichtlich seiner grenzflächenaktiven Eigenschaften sowie einer Strukturbildung in wässriger Phase charakterisiert. Die Emulsionspolymerisation mit dem polymeren PU-Emulgator am Beispiel von Styrol ist untersucht worden. Dabei sind die Partikelgrössen und deren Verteilung in Abhängigkeit von Reaktionsparametern mittels Photonen-Korrelations-Spektroskopie und durch Fluss-Feldfluss-Fraktionierung (F-FFF) bestimmt worden. Weiterhin wurde mittels Dilatometrie und Reaktionskalometrie die Polymerisationskinetik untersucht. Die Partikelmorphologie konnte durch Festkörper-NMR modelliert werden. Durch Atomic Force Microscopy (AFM) im Tapping mode konnte die Oberfläche und die Phasenseparation der polymeren Phasen charakterisiert werden. / This paper describes the synthesis of a reactive amphiphilic polyurethane, and its use as an emulsifier for the emulsion polymerization of styrene. The colloid properties and the structure of the emulsifier in the aqueous phase have been investigated. When the acrylic polymerization is carried out with hydrophobic monomers, we obtain a composite particle structure. The variation of particle size and particle size distribution as a function of the reaction parameters was measured by light scattering methods and Flow-fieldflow-fractionation (F-FFF) . Through investigation by dilatometry and reaction calorimetry it was possible to compare the polymerization process with that of common emulsion polymerization. Solid State NMR analysis allowed us to develop a core-shell model for the composite particle structure, and to determine the presence of an interphase layer between core and shell. Atomic Force Microscopy (AFM) methods were used to characterize the surface of the films, and tapping mode AFM was used to characterize the polymer phase separation on the micro scale.
86

Electrical Insulating Properties of Poly(Ethylene-co-Butyl Acrylate) Filled with Alumina Nanoparticles

Jäverberg, Nadejda January 2013 (has links)
In this work the electrical insulating properties of the nanocomposite materials based on poly(ethylene-co-butyl acrylate) filled with alumina nanoparticles are studied. The dielectric properties chosen for the evaluation are the dielectric permittivity and loss as well as the breakdown strength and the pre-breakdown currents. The reason for choosing these particular properties is partly due to the importance of these for the general electrical applications and partly due to the uncertainties involved for these particular properties of the nanocomposite materials. The importance of moisture absorption for the dielectric properties is outlined in this work. All measurements were performed in both dry conditions and after conditioning of the materials in humid environment until saturation. The data for moisture absorption was taken from the water absorption study performed at the Department of Fibre and Polymer Technology, KTH. The dielectric spectroscopy in frequency domain was employed for measuring dielectric permittivity and loss. Havriliak-Negami approximation was used for characterization of the measurement data and at the same time ensuring the fulfillment of the Kramers-Kronig relations. Results from the dielectric spectroscopy study in dry conditions suggest that dielectric spectroscopy can be used for evaluating nanoparticle dispersion in the host matrix, based on correlation between the morphology data obtained from SEM investigation and the scatter in the dielectric loss. The dielectric spectroscopy study performed on the nanocomposites after conditioning in humid environment showed that absorbed moisture has a distinct impact on the dielectric loss. Especially pronounced is its’ influence on the frequency behavior, when the dielectric loss peaks are shifted towards higher frequencies with increased moisture content. The nanocomposite materials characterized by higher specific surface area generally exhibit higher dielectric losses. Surface functionalization of the nanoparticles does not seem to have much influence on the dielectric loss in dry conditions. After conditioning in humid environment, however, the surface modification was shown to have a significant impact. Temperature is another significant factor for the frequency behavior of the dielectric loss: it was found that the studied nanocomposites can be characterized by Arrhenius activation. The breakdown strength and pre-breakdown currents study outlined the influence of moisture as well. The study indicated that surface treatment of the nanoparticles can enhance properties of the nanocomposite materials, namely aminopropyltriethoxy silane was an especially successful choice: • The highest breakdown strength was determined by the study for NDA6 material formulation in dry conditions. • After conditioning in humid environment the NDA6 material continued showing the best breakdown strength among the nanocomposite mate rials, as well as this value was close to the breakdown strength of the reference unfilled material. This study confirms the existence of the optimal nanofiller content or rather optimal specific surface area of the dispersed nanoparticles in the host matrix. The latter is supported by the comparison between the nanocomposites based on nanoparticles with two different specific surface areas, which shows that the dielectric properties worsen, i.e. the dielectric losses increase and the influence of absorbed moisture on the breakdown strength becomes more pronounced, for nanomaterials with larger specific surface area. The pre-breakdown currents were found to follow space-charge limited conduction mechanism reasonably well. The following conduction regimes were identified: constant region (likely due to measurement difficulties at low field strengths), Ohm’s regime, trap-filled-limit regime and trapfree dielectric regime. The breakdown usually occurred either during the trap-filled-limit regime, when the current increased dramatically for the small change in electric field, or during the trapfree dielectric regime. The threshold values between different conduction regimes seem to correlate well with the oxidation induction times (OIT), which in turn depend on the total specific surface area. The pre-breakdown currents tend to be highest for the materials filled with the untreated nanoparticles. Increased absorbed moisture content causes higher pre-breakdown currents for the nanocomposite materials, while for the reference unfilled material the pre-breakdown currents do not show such tendency. Generally it can be said that the repeatability in the measured data is higher for the nanocomposite materials in comparison to the unfilled host material, as was demonstrated by both dielectric spectroscopy and breakdown studies. / <p>QC 20130207</p>
87

Efeito da adi??o do poli(etileno acrilato de metila) (ema) e da fibra de linter de algod?o nas propriedades do poli(tereftalato de etileno) reciclado (petrec)

Pereira, Laurenice Martins 28 December 2014 (has links)
Made available in DSpace on 2014-12-17T14:07:18Z (GMT). No. of bitstreams: 1 LaureniceMP_DISSERT.pdf: 7523564 bytes, checksum: 3bb1b06da6a21522b0974a84935760a3 (MD5) Previous issue date: 2014-12-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The development of new materials to fill the demand of technological advances is a challenge for many researchers around the world. Strategies such as making blends and composites are promising alternatives to produce materials with different properties from those found in conventional polymers. The objective of this study is to evaluate the effect of adding the copolymer poly(ethylene methyl acrylate) (EMA) and cotton linter fibers (LB) on the properties of recycled poly(ethylene terephthalate) (PETrec) by the development of PETrec/EMA blend and PETrec/EMA/LB blend composite. In order to improve the properties of these materials were added as compatibilizers: Ethylene - methyl acrylate - glycidyl methacrylate terpolymer (EMA-GMA) and maleic anhydride grafted polyethylene (PE-g-MA). The samples were produced using a single screw extruder and then injection molded. The obtained materials were characterized by thermogravimetry (TG), melt flow index (MFI) mensurements, torque rheometry, pycnometry to determinate the density, tensile testing and scanning electron microscopy (SEM). The rheological results showed that the addition of the EMA copolymer increased the viscosity of the blend and LB reduces the viscosity of the blend composite. SEM analysis of the binary blend showed poor interfacial adhesion between the PETrec matrix and the EMA dispersed phase, as well as the blend composite of PETrec/EMA/LB also observed low adhesion with the LB fiber. The tensile tests showed that the increase of EMA percentage decreased the tensile strength and the Young s modulus, also lower EMA percentage samples had increased the elongation at break. The blend composite showed an increase in the tensile strength and in the Young`s modulus, and a decrease in the elongation at break. The blend formulations with lower EMA percentages showed better mechanical properties that agree with the particle size analysis which showed that these formulations presented a smaller diameter of the dispersed phase. The blend composite mechanical tests showed that this material is stronger and stiffer than the blend PETrec/EMA, whose properties have been reduced due to the presence of EMA rubbery phase. The use of EMA-GMA was effective in reducing the particle size of the EMA dispersed phase in the PETrec/EMA blend and PE-g-MA showed evidences of reaction with LB and physical mixture with the EMA / O desenvolvimento de novos materiais para atender as necessidades dos avan?os tecnol?gicos ? um desafio enfrentado por pesquisadores de todo o mundo. No que diz respeito aos materiais polim?ricos, estrat?gias como a confec??o de blendas e comp?sitos s?o alternativas promissoras para atender a demanda por materiais com propriedades diferentes das encontradas nos pol?meros convencionais. O objetivo deste trabalho ? avaliar o efeito da adi??o do copol?mero poli(etileno-acrilato de metila) (EMA) e da fibra de linter de algod?o (LB) nas propriedades do poli(tereftalato de etileno) reciclado (PETrec). Para isto, foram desenvolvidos a blenda PETrec/EMA e o comp?sito da blenda PETrec/EMA/LB. Com o intuito de melhorar as propriedades destes materiais foram adicionados agentes compatibilizantes: terpol?mero etileno-acrilato de metila-metacrilato de glicidila (EMA-GMA) e o polietileno enxertado com anidrido mal?ico (PE-g-MA). As misturas foram produzidas por meio de uma extrusora monorosca e, em seguida, moldados por inje??o. As caracteriza??es realizadas foram termogravimetria (TG), medida de ?ndice de fluidez (MFI), reometria de torque, determina??o da densidade por picnometria, ensaio de tra??o uniaxial e microscopia eletr?nica de varredura (MEV). Os resultados reol?gicos mostraram que a adi??o do copol?mero EMA aumentou a viscosidade da mistura e o LB reduziu a viscosidade da blenda PETrec/EMA. A an?lise por MEV da blenda bin?ria mostrou baixa ades?o interfacial entre a matriz de PETrec e a fase dispersa de EMA, assim como no comp?sito da blenda PETrec/EMA/LB, tamb?m observou-se uma baixa ades?o com a fibra de LB. Os ensaios de tra??o mostraram que o aumento da porcentagem de EMA diminuiu a resist?ncia m?xima e o m?dulo de elasticidade, e, para as formula??es com menor porcentagem de EMA verificou-se um aumento do alongamento na ruptura. O comp?sito da blenda apresentou um aumento na resist?ncia m?xima e no m?dulo de elasticidade, e uma redu??o no alongamento de ruptura. As formula??es da blenda com menores porcentagens de EMA apresentaram propriedades mec?nicas melhores, que corrobora com as an?lises de tamanho de part?cula que mostraram que estas formula??es apresentaram menor di?metro m?dio de fase dispersa. Os resultados de ensaios mec?nicos do comp?sito da blenda mostraram que essa mistura resultou em um material com maior resist?ncia mec?nica e rigidez do que a blenda PETrec/EMA, cujas propriedades foram reduzidas em fun??o da fase borrachosa EMA. O uso do EMA-GMA foi eficiente na redu??o do tamanho de part?culas da fase dispersa do EMA na blenda PETrec/EMA e o PE-g-MA apresentou ind?cio de rea??o com o LB e mistura f?sica com o EMA
88

Modification of Wood Surfaces via controlled Polymerization Methods

Königsmann, Martin 27 September 2018 (has links)
No description available.
89

Développement de surfaces fonctionnelles par polymérisation plasma à la pression atmosphérique : applications aux propriétés superhydrophobes, barrières aux gaz et aux UV / Development of functional thin film achieved by atmospheric pressure dielectric barrier discharge process : application of superhydrophobic surfaces, gas barrier and UV attenuation

Petersen, Julien 29 November 2012 (has links)
Le manuscrit porte sur l'élaboration de couches minces ayant des propriétés barrières aux liquides, aux gaz et aux ultra-violets. Pour réaliser nos différents systèmes, la technologie plasma à décharge à barrière diélectrique à la pression atmosphérique (DBD) a été utilisée. Dans la première partie, des films polymère plasma à base de 1H, 1H, 2H, 2H, Perfluorodecyl acrylate ont été développé. En fonction des paramètres plasma une surface dîtes superhydrophobe en une étape a été obtenue grâce à l'obtention d'un film composé de nanoparticules fluorés. La seconde partie des travaux a consisté à développer des films barrières aux gaz à partir de l'hexamethyldisiloxane. Ainsi, des films minces SiOx et multicouches SiOxHyCz/SiOx ont pu être obtenue afin d'améliorer les performances barrières de substrat PET et PEN. Enfin, l'obtention de film barrière aux UV a consisté à une croissance in-situ de nanoparticules de dioxyde de titane (TiO2) à partir du film polymère plasma. La matrice polymère constitué d'une structure siloxane et aminée plasma joue le rôle de nano-réacteur pour la croissance de cristaux de TiO2. / This works presents the development of plasma-polymrized surfaces for superhydrophobic, gas barrier and UV attenuation properties. These functional coatings have been deposited by means of atmospheric pressure dielectric barrier discharge (DBD). The first part deals on the plasma polymerization of the de 1H, 1H, 2H, 2H, Perfluorodecyl acrylate. According to the plasma parameters, surperhydrophobic coatings have obtained on several substrates. Morphologies analysis have shown the formation of fluorinate nanoparticles. The second part of the work was to develop gas barrier films from hexamethyldisiloxane. Thus, SiOx thin films and SiOxHyCz / SiOx multilayers have been obtained in order to improve the barrier performance of PET and PEN substrate. Finally, obtaining UV barrier film was to an in-situ growth of nanoparticles of titanium (TiO2) dioxide from the plasma polymer filin. The plasma polymer acts as a nano-reactor for the growth of TiO2 nanoparticles
90

Erhöhung der Prozesssicherheit durch optische inline Vernetzungsgrad- und Schichtdickenmessung für die Prozesskontrolle

Rueß, Ferdinand, Biberger, Amelie, Kücükpinar, Esra, Holländer, Andreas 30 May 2018 (has links) (PDF)
Es wird gezeigt, dass mit dem Fluoreszenzmesssystem sowohl die Schichtdicke als auch die Aushärtung detektiert werden kann. Durch das Erstellen von Eichkurven ist es so möglich, vollflächig, die genaue Schichtdicke der Beschichtung im laufenden Prozess inline zu bestimmen und Abweichungen in Echtzeit entgegenzuwirken. Zudem können so Unregelmäßigkeiten bei der Aushärtung der Lacke direkt erkannt und bei unzureichender Aushärtung der Anteil von Fehlproduktionen minimiert werden. Auch bei hochvernetzten Acrylatklebstoffen konnte gezeigt werden, dass mit dem System eine genaue Analyse der inneren Festigkeit vorgenommen werden kann. Diese Klebstoffe, mit teilweise unterschiedlichem chemischen Aufbau, aber gleichem E-Modul, emittieren dasselbe Maß an Fluoreszenz. Somit konnte gezeigt werden, dass mit der Fluoreszenzmessung, unabhängig von der chemischen Struktur, gleichbleibende Intensitäten gemessen und damit der Aushärtegrad bestimmt werden kann. Zur genauen Bestimmung der Schichtdicken mit dem Fluoreszenzmesssystem ist es notwendig genaue Eichkurven für jedes einzelne System zu erstellen. Auch ist es, im Falle der Molkeprotein Beschichtungen notwendig weitere Formulierungen zu testen um eine exakte Vorhersage des Vernetzungsgrads zu gewährleisten. Durch die Ergebnisse die mit den Acrylatklebstoffen erzielt wurden stellt sich die Frage, inwieweit eine Korrelation zwischen der chemischen Struktur des untersuchten Materials und der gemessenen Fluoreszenz dabei besteht. Es sollte die Fluoreszenz von weiteren Materialien, unterschiedlicher chemischer Struktur, gemessen und überprüft werden, ob ein Zusammenhang zu deren E-Modul besteht. Außerdem sind Materialien wie z.B. Klebstoffe und Lacke auf Polyurethanbasis, deren Aushärtung erst nach mehreren Tagen oder Wochen abgeschlossen ist, interessant. Dabei stellt sich die Frage, ob Abweichungen der Aushärtung schon direkt nach der Beschichtung, durch das Fluoreszenzmesssystem, detektiert und somit Fehlproduktionen schon frühzeitig erkennt werden können. [... aus Zusammenfassung und Ausblick]

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