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Dissertations / Theses on the topic 'Polymer tip'

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Published: 7 July 2024

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1

Xie, Shaoxiong. "COMPARATIVE STUDY ON TIP/TIA/ZRP/TEOS MODIFIED EPOXIDES RESIN: ANTI-CORROSION PERFORMANCE." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1534159109126582.

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2

Agapov, Rebecca L. "Advanced Scanning Probe Techniques for the Study of Polymer Surfaces." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1352922649.

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3

Rice, Reginald H. "Atomic force microscopy studies of thermal, mechanical and velocity dependent wear of thin polymer films." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/14955.

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Master of Science
Department of Physics
Robert Szoszkiewicz
Nanoscale modifications of polymer surfaces by scratching them with sharp tips with curvature radii of tens of nanometers and at variable temperatures are expected to provide wealth of information characterizing wear response of these polymers. Such studies are important in the light of understanding the nanoscale behavior of matter for future applications in advanced polymer coatings. This thesis describes how Atomic Force Microscopy (AFM) and hot-tip AFM (HT-AFM) methods were used to characterize thermal and mechanical properties of a 30 nm thick film of poly(styrene-block-ethylene oxide), PS-b-PEO, and modify its lamellar surface patterns. Additionally, it is revealed how contact AFM and HT-AFM methods can efficiently characterize the wear response of two popular polymer surfaces, poly(methyl methacrylate), PMMA, and polystyrene, PS. The AFM and HT-AFM studies on PS-b-PEO copolymer were aimed at producing spatial alignment of respective PS and PEO parts. Instead, however, surface ripples were obtained. These measurements are explained using mode I crack propagation model and stick-and-slip behavior of an AFM tip. In addition, HT-AFM studies allowed extraction of several thermo-physical properties of a PS-b-PEO film at local volumes containing about 30 attograms of a polymer. These thermo-physical quantities are: PEO melting enthalpy of, 111 ± 88 J g[superscript]-1, PS-b-PEO local specific heat of 3.6 ± 2.7 J g[superscript]-1K[superscript]-1, and molecular free energy of Helmholtz of 10[superscript]-20 J nm[superscript]-2 for the PEO within PS-b-PEO. Utilizing a spiral scan pattern at constant angular speed and at various temperatures at the AFM tip-polymer interfaces, the wear response of PS and PMMA polymers was characterized. Cross-sections along the obtained spiral wear patterns provided plots of polymer corrugation as a function of scanning speed. From these studies it was found that the corrugation of the modified polymer surface decays exponentially with linear velocity of the scanning tip.
4

Hazra, Sumit Kumar. "Crazing and yielding in polyethylene under impact." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369223.

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5

León, Albiter Noel. "On the fracture behavior of ductile polymer films : notch quality, essential work of fracture, J-integral, and crack tip opening displacement." Doctoral thesis, Universitat Politècnica de Catalunya, 2018. http://hdl.handle.net/10803/565501.

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Polymers have a wide range of applications. Their ability to be shaped into multiple forms makes it possible to obtain polymer films, which are highly used in industries such as food and pharmaceuticals. Characterization of polymer films using the classical mechanical properties is well-defined; however, this is not the case for the fracture properties. The overall aim of this work was to analyze in full-detail the fracture behavior of ductile polymer films by applying the appropriate fracture mechanics approaches. The first part of the thesis aimed to investigate the existing relationships between the specific essential work of fracture, the J-value at crack initiation, and crack tip opening displacement at crack initiation values and find clear evidence that makes the specific essential work of fracture the specific energy at crack initiation, that is, an initiation value. To do this, the digital image correlation technique was applied in double edge notched tension specimens. Applying this technique makes it possible to measure the displacement and ligament length at the same time, allowing that the essential work of fracture, the J-integral, and the crack tip opening displacement fracture approaches to be performed in a single set of double edge notched tension specimens. The second part of the thesis was focused on analyzing the influence of the notch quality on the fracture behavior. The specimen preparation, particularly the notch sharpening technique, has been studied in more depth. With the purpose of seeing the influence of the notch sharpening procedure, several techniques have been used, including femtosecond laser ablation, razor blade sliding on specimens at room temperature and frozen by liquid nitrogen, saw cutting, plastically deformed saw cutting, scalpel sliding and drilled holes used as notches. The results revealed that all of the femtolaser sharpened notches had very consistent, sharp notches without plastic deformation in front of the notch tip. Instead, the razor blade sliding technique (the generalized way to sharpen notches in ductile polymer films) produced very sharp cracks, as sharp as the femtolaser ones, but the different compressive component of the sliding force that was applied by the operator generated notches with different levels of plastic deformation ahead of the notch tip. As different notch sharpening techniques produce different levels of plastic deformation at the crack tip, differences would also be expected in the shape and size of the stress-displacement curves. In the third part of the thesis, the shape and size of the stress-displacement curves that were notched in distinct ways were analyzed to clarify their EWF behavior. In the propagation region, it is also identified the parabolic shape of the stress-displacement curves, which modeled relates the specific non-essential work of fracture with the stress at crack initiation and the extension ratio during the crack growth.
Los materiales poliméricos poseen un amplio rango de aplicaciones. Su habilidad de adquirir múltiples formas hace posible obtener películas de polímero, las cuales son altamente usadas en industrias como la de alimentos y productos farmacéuticos. La caracterización de dichas películas de polímero usando propiedades mecánicas clásicas se encuentra bien definido; sin embargo, este no es el caso con las propiedades a fractura. El objetivo general de este trabajo fue analizar en detalle el comportamiento a fractura de películas de polímero dúctiles mediante la aplicación de los enfoques adecuados de la mecánica de la fractura. La primera parte de la tesis investiga las relaciones existentes entre el trabajo esencial específico de fractura, el valor de la integral J de iniciación del crecimiento de la grieta y el desplazamiento crítico para la apertura de la punta de la grieta, ademas de encontrar pruebas claras que hacen al trabajo esencial específico de fractura la energía específica necesaria para el crecimiento de grieta, es decir, un valor de iniciación. Para hacer esto, se aplicó la técnica de correlación de imágenes digitales a probetas de doble entalla sometidas a tracción. Esta técnica permite medir el desplazamiento y la longitud de ligamento al mismo tiempo, lo que hace posible que el trabajo esencial de fractura, la integral J y el desplazamiento de apertura en la punta de la grieta se puedan realizar en un único conjunto de probetas de doble entalla sometidas a tracción. La segunda parte de la tesis se centró en analizar la influencia de la calidad de la entalla en el comportamiento a la fractura. La preparación de la muestra, particularmente la técnica de agudización empleada en la entalla, se ha estudiado con mas profundidad. Con el propósito de ver la influencia del procedimiento de agudización de la entalla, se han utilizado varias técnicas, entre las que se incluyen la ablación con láser de femtosegundo, agudización con cuchilla de afeitar sobre muestras a temperatura ambiente y congeladas con nitrógeno líquido, entallas realizadas con corte de sierra, entallas realizadas con corte de sierra deformadas plásticamente, agudización con bisturí y agujeros taladrados usados como entallas. los resultados revelaron que todas las entallas agudizadas con femtolaser eran muy consistentes y agudas, sin deformación plástica en frente de la punta de la grieta. En cambio, la técnica con cuchilla de afeitar produjo grietas muy agudas, tan agudas como las del femtolaser, pero diferencias en la fuerza compresiva usada por parte del operador al momento de aplicar la técnica, generó entallas con diferentes niveles de deformación plástica por delante de la punta de la grieta. Ya que las diferentes técnicas de agudización producen diferentes niveles de deformación plástica en la punta de la grieta, también se esperarían diferencias en la forma y el tamaño de la curvas tensión - desplazamiento. En la tercera parte de la tesis, la forma y el tamaño de curvas tensión - desplazamiento de especímenes que fueron entallados de diversas maneras fueron analizadas con el objetivo de clarificar su comportamiento a fractura. También, en la región de propagación se identifica la forma parabólica de las curvas tensión - desplazamiento, la cual modelada relaciona el trabajo especifico no esencial de fractura con la tensión de iniciación de crecimiento de grieta y la razón de extensión durante el crecimiento de grieta
6

Pham, Thi Nhung. "Fabry-Perot interferometer based on end-of-fiber polymer microtip for chemical sensing." Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0006.

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Les interféromètres Fabry-Perot (FPI) ont reçu un grand intérêt pour leur utilisation en tant que capteurs. Les FPI sont constitués d'une cavité optique avec des surfaces parallèles qui réfléchissent la lumière incidente, produisant un signal interférométrique optique. Ce signal dépend de la distance entre les surfaces réfléchissantes et de l'indice de réfraction de la cavité, qui sont sensibles aux variations d’humidité, de température, de pression et du matériau. Les FPI peuvent être attachés à des fibres optiques, qui fonctionnent comme un guide d'ondes pour le signal incident et le signal réfléchi, et former ainsi des capteurs compacts. Cette thèse présente des capteurs chimiques à base de FPI incorporant une micropointe en polymère structurée à l'extrémité d'une fibre optique, étudiés pour la détection d'humidité, d'eau et de cibles chimiques.Tout d'abord, nous développons une pointe de triacrylate de pentaérythritol (PETA) sur la facette d'une fibre optique par photopolymérisation autoguidée. Une extrémité de la fibre est placée dans une goutte de PETA et la photopolymérisation est activée par un laser de 375 nm injecté à l'autre extrémité de la fibre. Les conditions optimales pour former une pointe PETA mécaniquement stable sont 1μW de puissance laser × 1s de temps d'exposition. Cependant, les chaînes PETA ne sont pas complètement polymérisées lors de cette étape, ce qui entraîne une fréquence de résonance instable de la pointe. La pointe doit donc être post-polymérisée sous une lampe UV de 365nm pour obtenir une caractéristique dynamique stable, avant leur application en tant que capteur.Deuxièmement, nous démontrons que la pointe PETA est un capteur efficace pour détecter l'humidité. Elle fonctionne comme une cavité optique formée entre le cœur de la fibre/PETA et l'interface PETA/environnement, ce qui permet d'obtenir un signal interférométrique clair. Le signal FPI de la pointe est très sensible à l'humidité de l'air grâce aux groupes hydroxyles du PETA, qui absorbent les molécules d'eau dans l'air humide, induisant un gonflement de la pointe. La longueur et/ou l'indice de réfraction sont donc modifiés, ce qui entraîne une variation du signal interférométrique. La pointe présente une sensibilité constante de 90 pm/%RH, équivalent à une sensibilité relative de 104 ppm/%RH pour une plage d'humidité de 30 à 80 %. La détection est hautement reproductible et stable. En outre, l'effet de la température est négligeable, favorisant leur potentiel d’application.Ensuite, nous appliquons les pointes PETA basées sur le FPI pour déterminer la teneur en eau de solutions de glycérol et d'éthylène glycol. Le signal FPI de la pointe PETA varie de manière non linéaire lorsque la teneur en eau passe de 0 à 100% en poids. La variation du signal FPI est due à la contraction de la pointe, qui est liée à la perte d'eau à l'intérieur de la structure PETA. Lorsque la contamination par l'eau est inférieure à 10%, la pointe présente une sensibilité de 394 pm/wt.% et 226 pm/wt.% pour les solutions de glycérol et d'éthylène glycol, respectivement. Ainsi, la pointe PETA basée sur le FPI présente un grand potentiel pour la détermination de la teneur en eau de solutions aqueuses, y compris les hydrocarbures.Enfin, une pointe constituée d'un cœur PETA et d'une enveloppe de polymères à empreintes moléculaires (MIP) a été mise au point pour détecter la Dansyl-L-phénylalanine. La pointe PETA est initialement fabriquée en utilisant la polymérisation autoguidée et les MIP sont ensuite copolymérisés pour former une fine couche d'enveloppe autour de la pointe PETA. Lors de la détection sélective de la Dansyl-L-phénylalanine, l'indice de réfraction de la couche de MIP change, ce qui entraîne une modification du signal FPI de l'ensemble de la pointe PETA/MIP. Cette méthode simple offre de nouvelles possibilités pour créer des capteurs à fibre optique MIP à base de FPI applicables à une large gamme d'analytes, qu’ils soient fluorescents ou non
Fabry−Perot interferometers (FPIs) have received a significant attention for their use in sensor applications. FPIs consist of an optical cavity with separate parallel reflecting surfaces which reflect incident light, resulting in an optical interferometric signal. The FPI signal depends on the distance between the reflecting surfaces and the refractive index of the cavity medium, which are sensitive to variation of environment humidity, temperature, pressure, and material. FPIs can be attached to optical fibers to form compact fiber optic FPI-based sensors in which the optical fiber works as a waveguide for both incident and reflected signal. This thesis presents FPI-based chemical sensors incorporating a polymer microtip located at the end of an optical fiber and characterizes their sensing capabilities for humidity, water, and chemical targets.Firstly, we develop a pentaerythritol triacrylate (PETA) tip on the facet of an optical fiber by a self-guiding photopolymerization. One end of the optical fiber is placed inside a PETA droplet and the self-guiding photopolymerization of PETA is actuated by a 375 nm laser injected to the other end of the fiber. The optimal conditions to form a straight and mechanically stable PETA tip are 1.0 μW of laser power × 1.0 second of exposure time. However, the PETA chains do not completely polymerize during this self-polymerization, leading to an unstable dynamic resonant frequency of the tip. Thus, the tip needs a post-polymerization under a UV 365 nm lamp to achieve a stable dynamic characteristic, which is applicable for further sensing applications.Secondly, we demonstrate the PETA tip as an effective sensor to detect humidity. The PETA tip acts as an optical cavity formed between the fiber-core/PETA and the PETA/environment interface, resulting in a clear interferometric signal. The FPI signal of the tip is highly sensitive to humidity in the air. This is due to hydroxyl groups within the PETA structure, which strongly absorb water molecules in the humid air and significantly swell the tip. The length and/or the refractive index of the tip are therefore changed, resulting in a FPI shift. The tip exhibits a consistent sensitivity of 90pm/%RH, equivalent to a relative sensitivity of 104 ppm/%RH in the humidity range from 30 to 80%. The sensing performance is highly reproducible and stable. Furthermore, the cross effect of the temperature is negligible, indicating a great practical potential for the devices.Next, we apply the FPI-based PETA tips to determine the water content in glycerol and ethylene glycol solutions. The FPI signal of the PETA tip shifts nonlinearly towards longer wavelengths as the water content increases from 0 to 100 wt.%. The shift in the FPI signal occurs due to the contraction in the tip length, which is linked to the loss of water inside the PETA structure caused by the hydrophilic solutions. When the water contamination is below 10 wt.%, the tip shows a sensitivity of 394 pm/wt.% and 226 pm/wt.% for glycerol and ethylene glycol solutions, respectively. Therefore, the FPI-based PETA tip shows a great potential in determining water content in hydrophilic aqueous solutions, including hydrocarbons.Finally, a tip consisting of a PETA core and a shell of molecularly imprinted polymers (MIPs) is developed for detecting Dansyl-L-phenylalanine. The PETA tip is initially fabricated using the self-guiding polymerization and MIPs are then copolymerized to form a thin shell layer around the PETA tip. Upon the selective binding of Dansyl-L-phenylalanine, the refractive index of the MIP layer changes, leading to the change in the FPI signal of the whole PETA/MIP tip. This straightforward and affordable method offers new innovative possibilities for creating FPI-based MIP fiber optic sensors, which can be applied for a wide range of analytes, including both non-fluorescent and fluorescent targets
7

Shi, Xian [Verfasser], and Achim [Akademischer Betreuer] Hartschuh. "Tip-enhanced near-field optical microscopy of single-walled carbon nanotube/polymer conjugates and improvements of the image contrast / Xian Shi ; Betreuer: Achim Hartschuh." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2017. http://d-nb.info/1151447404/34.

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8

Barrios, Carlos A. "Modified Scanning Probes for the Analysis of Polymer Surfaces." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1249315424.

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9

Solomão, Zenaide. "Desenvolvimento e caracterização de compósitos de Poli (E-Caprolactona) PCL e ß-Fosfato Tricálcico (ß-TCP) para uso em biomateriais." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263534.

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Abstract:
Orientador: Cecília Amélia de Carvalho Zavaglia
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-17T22:38:20Z (GMT). No. of bitstreams: 1 Solomao_Zenaide_M.pdf: 4852275 bytes, checksum: e8aeb44e410022a37476432c0111160d (MD5) Previous issue date: 2011
Resumo: A utilização de biomateriais para substituir, reparar tecidos e órgãos lesados dos seres humanos tem aumentado muito ultimamente devido a diversos fatores como o crescimento da população e a sua maior expectativa de vida. A engenharia tecidual é um campo interdisciplinar que integra princípios da biologia celular e molecular, química, genética, ciências dos materiais e engenharia biomédica, para produzir compósitos tridimensionais inovativos, capazes de substituir tecidos biológicos. O desenvolvimento de novo biomaterial pode ajudar a solucionar este problema, utilizando o método de evaporação de solvente. Este trabalho teve como objetivos: sintetizar e caracterizar o ß-TCP através do método via seca; desenvolver e caracterizar as membranas de poli ('epsilon'-caprolactona) densas e porosas (scaffolds) utilizando dois solventes; preparar e caracterizar os compósitos densos e porosos PCL/ß-TCP; fazer uma avaliação da biocompatibilidade in vitro desses materiais. As seguintes técnicas de caracterização foram utilizadas: MO, MEV, EDS, DRX, TGA,DSC, ensaios mecânicos de tração, teste de viabilidade celular e atividade de fosfatase alcalina. Foi também analisada a sua degradação hidrolitica em solução tampão fosfato (PBS). Essas técnicas foram adequadas para diferenciar as amostras preparadas com os dois solventes utilizados: clorofórmio e diclorometano. Os ensaios mostraram que o último forneceu amostras mais resistentes mecanicamente, mantendo as propriedades térmicas do PCL puro sem alterações, com a adição das partículas do ß-TCP. A biocompatibilidade foi analisada através das normas conhecidas (ASTM e ABNT) e foi possível concluir que os materiais confeccionados são biocompativeis e a atividade de fosfatase alcalina (ALP) favoreceu o crescimento celular na membrana porosa. As avaliações in vitro não mostraram mudanças significativas nas composições preparadas com o solvente clorofórmio. Os materiais estudados possuem um grande potencial para aplicação em substitutos do tecido ósseo
Abstract: The use of biomaterials to replace, repair damaged tissues and organs of humans has greatly increased lately due to various factors such as population growth and greater life expectancy. Tissue engineering is an interdisciplinary field that incorporates principles of molecular and cellular biology, chemistry, genetics, materials science and biomedical engineering to produce innovative three-dimensional composites, capable of replacing tissue. The development of new biomaterial can help solutions this problem by using on whole of evaporation of solvent. This work aimed to synthesize and characterize the ß-TCP by the dry method; develop and characterize the membranes of poly ('épsilon'-caprolactone) porous and dense (scaffolds) using two solvents, to prepare and characterize the dense and porous PCL composites / ß-TCP, perform an evaluation of in vitro biocompatibility of these materials. The following characterization techniques were used: OM, SEM, EDS, XRD, TGA, DSC, mechanical testing, testing cell viability, alkaline phosphatase activity. We also analyzed its hydrolytic degradation in phosphate buffer solution (PBS). These techniques were adequate to differentiate the samples prepared with two solvents used, chloroform and dichloromethane. The tests showed that the samples provided last more mechanically resistant, keeping the thermal properties of pure PCL unchanged with the addition of particles of ß-TCP. The biocompatibility was determined by known standards (ASTM and ABNT) and we can conclude that the materials are biocompatible and made (ALP), promoted cell growth in the porous membrane. The in vitro evaluations showed no significant changes in the compositions prepared with the solvent chloroform. The materials studied have a great potential for application in bone tissue substitutes
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
10

Liang, Wenfeng. "Metal Organic Composites Derived Tin Dioxide/C Nanoparticles For Sodium-Ion Battery." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1460304081.

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11

Jin, Changqing. "FTIR studies of TiO₂ : pigmented polymer photodegradation." Thesis, University of Newcastle Upon Tyne, 2004. http://hdl.handle.net/10443/1056.

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A novel method (in-situ quantitative infrared spectroscopy of evolved C02) for studying photo-degradation has been developed and applied to the study of several different polymers including a series of polyethylene and poly (vinyl chloride) samples containing Ti02 pigments with different photo-activitics. Infrared (IR) analysis was used to monitor carbon dioxide emitted from samples exposed to ultraviolet irradiation (UV) in atmospheres of differing composition. The experiments were conducted in a specially constructed cell that permits simultaneous UV exposure of the sample and IR interrogation of the vapour in the cell. It has been demonstrated that the in-situ gas-phase method permits a fast and convenient way of assessing the durability of pigmented and unpigmented polymer. A single test on one material occupied about 7 hours - very much less than conventional artificial weathering exposures. Excellent correlation between the C02 method and the conventional method for measuring carbonyl groups in the polyethylene films has been demonstrated, The Ti02 pigments used included anatase and rutiles with different surface treatments. Anatase-pigmented material gave significantly higher C02 emission than unpigmented polyethylene. The rutile-pigmented polyethylenes either gave reduced C02 emission or enhanced emission, according to the surface treatment. The ranking of the pigments as protectants or pro-degradants coincided with that obtained from much more time consuming laboratory testing and field experience. Similar results were obtained for the poly (vinyl chloride). The CO2 method is a convenient way to study the factors (humidity, oxygen concentration and UV intensity or wavelength), which influence the rate of carbon dioxide evolution i. e. the rate of photo-oxidation of the polymers. Blown polyethylene(PE) film was exposed to UV irradiation while held under tensile stress in a specially designed metal frame. The chemical degradation was followed using the FTIR carbonyl index. Tests were conducted on unpigmented PE and on a series of five PEs containing TiO2 pigments with different photo-activities. The yield strengths measured in tensile tests on unexposed films were typically 10 % greater in the longitudinal( machine)direction than in the transverse direction. UV exposures were conducted with stress applied both parallel and transverse to the machine direction.For all six materials, tensile stress accelerated carbonyl group development, Some samples cracked during UV exposure in tension and did so in a shorter time if the stress was applied in the machine direction than if it was transverse to it. The carbonyl index at the onset of cracking was lower for longitudinal samples than for transverse samples. Unpigmented PE was slightly more sensitive to transverse strain and the anatasepigmented PE slightly more sensitive to longitudinal strain.
12

Liu, Ruofan. "Assessment of Composite Railroad Tie Cracking." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1386688325.

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13

Scherger, Jacob D. "Expanding Tip Enhanced Raman Spectroscopy: Blinking Measurements and Alternative Probe Materials." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1510657402180872.

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14

Hall, David Steven. "Metal polymer adhesion for packaging materials." Thesis, Oxford Brookes University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245702.

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15

Zeiner, Tim [Verfasser]. "Phase- and Interfacial Behaviour of Hyperbranched Polymer Solutions / Tim Zeiner." München : Verlag Dr. Hut, 2011. http://d-nb.info/1010446754/34.

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16

Tas, Huseyin. "Coordination Polymerization Of Cyclic Ethers By Metal Xanthates And Carbamates." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1225028/index.pdf.

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Zinc xanthates are active catalysts in stereoregular polymerization of propylene oxide and markedly more stable than that of known classical stereoregular catalysts. But steric control of zinc xanthates is weaker. To find more effective catalyst systems the isopropyl xanthates of Cu, Pb, Ni, Fe, Al and Sn are investigated and only copper (Cu(isoPr)Xt) and tin (Sn(isoPr)Xt) isopropyl xanthates were appeared to be active, but Cu(isoPr)Xt yielded only low molecular weight product. Therefore Sn(isoPr)Xt system was investigated in detail in polymerization of propylene oxide (PO). Polymerization of PO with this catalyst produced two contrasting polymers
high molar mass, crystalline (K-polymer) and low molar mass (D-polymer). Formation of double bonds in D-polymer was thought to be due to as an anionic process. Polymerization reactions were studied by changing polymerization conditions and reacting catalyst with predetermined amount of water. It&
#8217
s found that Sn(isoPr)Xt have considerably low efficiency than that of Zn(isoPr)Xt catalyst. The yield linearly increases by increasing catalyst concentration. The propagation is competed by termination or transfer process hence overall activation energy is negative. Some mechanistic features of this system was also discussed. The catalytical activity of carbamates in this field has also been reported, without any information about catalytical efficiency and stereoregularity of the process. Therefore zinc diethyl dithiocarbamate was also studied and found as an active catalyst in stereoregular polymerization but it showed weaker efficiency in the PO polymerization than that of Zn(isoPr)Xt catalyst (about 12 times weaker).
17

Bahrami, Sanaz. "Low-Profile Polymer Actuator Fabrication for Spastic Hand Exoskeletons." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37953.

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Spasticity is a neurological impairment that presents itself in the form of a continuous muscle contraction, with the key motor deficit being impaired hand function. Hand exoskeleton technologies play a vital role in the therapeutic rehabilitation of this condition. The optimal design of these devices is currently a challenge due to the limited availability of actuation devices that are light weight, portable, and aesthetically pleasing. Natural muscles have many favourable characteristics, such as their high power-to-weight ratio, efficient energy conversion, and fast actuation times. Unfortunately, traditional systems such as pneumatics muscles and electromagnetic motors have yet to attain similar properties. These traditional actuators exhibit hysteretic performance, high manufacturing cost, low stroke, and limited cycle life. In recent years a new category of actuators has been developed from highly twisted and coiled low-cost nylon fibres such as fishing line and conductive sewing thread. These muscles produce a high specific work per cycle with a reversible contraction. This thesis develops and tests these twisted and coiled polymer (TCP) actuators using various nylon and polyethylene polymers in order to establish a foundation for their implementation as a novel actuation device in a spastic hand exoskeleton. An initial comprehensive experimental evaluation of several nylon fibres is completed by attempting to reproduce the work of previous researchers. Subsequently, the information obtained is taken and adapted to the development of UHMWPE TCPs and other types of nylon monofilament. This thesis characterizes the contractility and force output of these novel actuation devices.
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Lounis, Sebastien Dahmane. "The influence of dopant distribution on the optoelectronic properties of tin-doped indium oxide nanocrystals and nanocrystal films." Thesis, University of California, Berkeley, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3686398.

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Colloidally prepared nanocrystals of transparent conducting oxide (TCO) semiconductors have emerged in the past decade as an exciting new class of plasmonic materials. In recent years, there has been tremendous progress in developing synthetic methods for the growth of these nanocrystals, basic characterization of their properties, and their successful integration into optoelectronic and electrochemical devices. However, many fundamental questions remain about the physics of localized surface plasmon resonance (LSPR) in these materials, and how their optoelectronic properties derive from their underlying structural properties. In particular, the influence of the concentration and distribution of dopant ions and compensating defects on the optoelectronic properties of TCO nanocrystals has seen little investigation.

Indium tin oxide (ITO) is the most widely studied and commercially deployed TCO. Herein we investigate the role of the distribution of tin dopants on the optoelectronic properties of colloidally prepared ITO nanocrystals. Owing to a high free electron density, ITO nanocrystals display strong LSPR absorption in the near infrared. Depending on the particular organic ligands used, they are soluble in various solvents and can readily be integrated into densely packed nanocrystal films with high conductivities. Using a combination of spectroscopic techniques, modeling and simulation of the optical properties of the nanocrystals using the Drude model, and transport measurements, it is demonstrated herein that the radial distribution of tin dopants has a strong effect on the optoelectronic properties of ITO nanocrystals.

ITO nanocrystals were synthesized in both surface-segregated and uniformly distributed dopant profiles. Temperature dependent measurements of optical absorbance were first combined with Drude modeling to extract the internal electrical properties of the ITO nanocrystals, demonstrating that they are well-behaved degenerately doped semiconductors displaying finite conductivity at low temperature and room temperature conductivity reduced by one order of magnitude from that of high-quality thin film ITO.

Synchrotron based x-ray photoelectron spectroscopy (XPS) was then employed to perform detailed depth profiling of the elemental composition of ITO nanocrystals, confirming the degree of dopant surface-segregation. Based on free carrier concentrations extracted from Drude fitting of LSPR absorbance, an inverse correlation was found between surface segregation of tin and overall dopant activation. Furthermore, radial distribution of dopants was found to significantly affect the lineshape and quality factor of the LSPR absorbance. ITO nanocrystals with highly surface segregated dopants displayed symmetric LSPRs with high quality factors, while uniformly doped ITO nanocrystals displayed asymmetric LSPRs with reduced quality factors. These effects are attributed to damping of the plasmon by Coulombic scattering off ionized dopant impurities.

Finally, the distribution of dopants is also found to influence the conductivity of ITO nanocrystal films. Films made from nanocrystals with a high degree of surface segregation demonstrated one order of magnitude higher conductivity than those based on uniformly doped crystals. However, no evidence was found for differences in the surface electronic structure from one type of crystal to the other based on XPS and the exact mechanism for this difference is still not understood.

Several future studies to further illuminate the influence of dopant distribution on ITO nanocrystals are suggested. Using synchrotron radiation, detailed photoelectron spectroscopy on clean ITO nanocrystal surfaces, single-nanoparticle optical measurements, and hard x-ray structural studies will all be instructive in elucidating the interaction between oscillating free electrons and defect scattering centers when a plasmon is excited. In addition, measurements of temperature and surface treatment-dependent conductivity with carefully controlled atmosphere and surface chemistry will be needed in order to better understand the transport properties of ITO nanocrystal films. Each of these studies will enable better fundamental knowledge of the plasmonic properties of nanostructures and improve the development of nanocrystal based plasmonic devices.

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Potoczny, Grzegorz A. "Electro-mechanical behaviour of indium tin oxide coated polymer substrates for flexible electronics." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3475/.

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Highly conductive (3.0 - 5.0 x 10 \(^{-4}\) \( \Omega\) cm) and transparent (80 – 85% ) ITO films were successfully fabricated on glass and polymer substrates (PET, PEN and PC) by pulsed laser deposition at low temperatures (24 – 150 °C). The influence of deposition conditions on the structural and physical properties of ITO-coated glass substrates was studied. The samples were investigated using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD), the fourpoint probe and a spectrophotometer. Sol-gel derived ITO films dip-coated on glass substrates were also studied. The optimum film obtained at a firing temperature of 600 °C had a resistivity of 1.8 x 10 \(^{-2}\) \( \Omega\) cm, and optical transmittance of 80%. The electro-mechanical behaviour of ITO/polymer systems was investigated under uniaxial tension and controlled buckling in tension and compression. The resistance changes were monitored in situ. Cracking and buckling delamination failure modes were observed for all samples investigated at critical strains raging from 2.8 to 3.4%, and from 7.0 to 8.0%, respectively. The results showed that the dominant critical failure mode depends on the applied stress conditions. The ITO/PEN samples showed high flexibility; the samples were buckled in tension down to a 2.6 mm radius of curvature before cracks start to occur.
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Lin, Feng. "Preparation and Characterization of Polymer TiO2 Nanocomposites via In-situ Polymerization." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2849.

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Polymer nanocomposites are already a part of many important of worldwide businesses: automotive (molded part in cars), electronics and electrical engineering, household products, packaging industry, aircraft interiors, appliance components, security equipments. Among many nanocomposite precursors, TiO2 nanopowder is increasingly being investigated due to its special properties.

The objective of this work is to synthesize and characterize polymer-TiO2 hybrid nanocomposites. When dispersed at the nanoscale level TiO2 could act as visually transparent UV filters and high-thermomechanical-performance materials. The synthesis strategy involved two steps. Firstly, aggregated TiO2, as received, was modified by 3-trimethoxysilyl propylmethacrylate aimed at altering its surface characteristics. The effect of modifier concentration on changing the physicochemical properties of TiO2 surface was evaluated. Size distribution of unmodified and modified TiO2 nanopowders was measured using a particle size analyzer. The qualitative and quantitative grafting of vinyl groups on TiO2 surface was investigated with Fourier transform-infrared (FTIR) and proton nuclear magnetic resonance (1H-NMR) spectroscopy. Secondly, styrene monomer was then added to carry out copolymerization with vinyl groups on the modified TiO2 by free radical initiator 2,2-azobis isobutyronitrile (AIBN) in bulk medium. FTIR spectra confirmed the formation of nanocomposites with polystyrene chains chemically linked to the surface of TiO2 nanopowders. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicated that the resulting nanocomposites displayed higher thermal stability and maintained similar glass transition temperatures (Tg) compared with pure PS. Ultraviolet ?visible spectroscopy (UV-Vis) investigated that these nanocomposites have improved optical properties potentially acting as visually transparent UV filters. Such incremented properties were attributed to the nancoscale dispersion (20-50nm size) of TiO2 into polystyrene matrix, which morphology was observed by scanning electron microscopy (SEM).
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Ohenoja, K. (Katja). "Particle size distribution and suspension stability in aqueous submicron grinding of CaCO3 and TiO2." Doctoral thesis, Oulun yliopisto, 2014. http://urn.fi/urn:isbn:9789526205502.

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Abstract During the past decade submicron and nanoparticles have aroused a wide interest and gained new applications due to their high surface area and strength. Grinding with a wet stirred media mill is usually the last process step before the submicron or nanoparticles are added to an application, and the step where the final particle size distribution is achieved. Since stirred media milling is an energy-intensive process, energy efficiency should be optimized. This can be done by determining the optimum operational parameters for the mill and using the highest possible solids concentration. The solids concentration can be increased by controlling particle-particle interactions with stabilization chemicals, e.g. polymers. This thesis concerns parameters and grinding aids affecting the particle size distribution and suspension stability of the aqueous submicron grinding of calcium carbonate (CaCO3) and titanium dioxide (TiO2) in stirred media mills. TiO2 particles are aggregates produced via a bottom-up method, while CaCO3 are primary mineral particles produced by a top-down method. The most energy efficient grinding of TiO2 to a 300 nm particle size with the narrowest possible particle size distribution was obtained with the lowest stress energy, implying the smallest grinding medium size. It was observed that electrosteric stabilization with sodium polyacrylates was effective for TiO2, and sodium polyacrylate with a molecular weight of 12500 g/mol was found to be the most effective for reducing the viscosity of the suspension. As with TiO2, electrosteric stabilization with sodium polyacrylates was also found to be effective for CaCO3, but in this case sodium polyacrylate with a lower polydispersity index was more effective, showing a better stabilization potential in micron and submicron grinding and reducing the viscosity and particle size to a greater extent. Nanogrinding experiments were performed for a CaCO3 suspension with low PDI sodium polyacrylate and it was found to be possible to obtain a particle size of 26 nm, smaller than any size previously reported when grinding CaCO3
Tiivistelmä Viimeisen kymmenen vuoden aikana alle yhden mikrometrin partikkelit ovat herättäneet kiinnostusta ja niille on kehitetty uusia sovelluksia niiden suuren pinta-alan ja lujuuden ansiosta. Ultrahienojauhatus märkähelmimyllyllä on useimmiten viimeinen prosessivaihe ennen partikkelien lisäämistä sovelluskohteeseen ja siinä saavutetaan partikkelien lopullinen partikkelikokojakauma. Helmimyllyjauhatuksen energiankulutus minimoidaan etsimällä optimioperointiparametrit kullekin jauhatusprosessille ja käyttämällä korkeinta mahdollista suspension kuiva-ainepitoisuutta. Suspension kuiva-ainepitoisuutta voidaan nostaa hallitsemalla partikkelien välisiä vuorovaikutuksia stabilointiaineilla, kuten polymeereillä. Tässä väitöskirjassa tutkittiin operointiparametrien ja jauhatusapuaineiden vaikutusta titaanidioksidin (TiO2) ja kalsiumkarbonaatin (CaCO3) partikkelikokojakaumaan ja lietteen stabiilisuuteen submikronijauhatuksessa. Tutkitut TiO2-partikkelit olivat aggregaatteja, jotka oli valmistettu sulfaattiprosessilla saostamalla, ja tutkitut CaCO3-partikkelit olivat primäärisiä mineraalipartikkeleita. TiO2-partikkeleille saavutettiin energiatehokkain jauhatus ja samalla toivottu partikkelikokojakauma, eli mediaani 300 nm ja mahdollisimman kapea jakauma, pienillä helmillä, jotka aiheuttavat partikkeleihin pienimmän puristusenergian. Elektrosteerinen stabilointi käyttämällä natriumpolyakrylaatteja stabilointiaineena havaittiin tehokkaaksi menetelmäksi hallita TiO2-partikkelien välisiä vuorovaikutuksia. Natriumpolyakrylaatti, jonka molekyylimassa oli 12500 g/mol, oli tehokkain TiO2-partikkeleille alentaen suspension viskositeettiä eniten. Myös CaCO3-partikkeleille elektrosteerinen stabilointi natriumpolyakrylaatteja käyttäen oli tehokkain stabilointimenetelmä. Myös natriumpolyakrylaattien polydispersiteetti-indeksin vaikutusta tutkittiin CaCO3-suspensioille. Tulokset osoittivat matalan polydispersiteetti-indeksin olevan tehokkaampi alentaen viskositteettia ja pienentäen partikkelikokoa tehokkaammin kuin natriumpolyakrylaatti, jolla oli korkeampi polydispersitetti-indeksi. Tämän vuoksi natriumpolyakrylaatti, jolla oli matala polydispersiteetti-indeksi, valittiin nanojauhatuskokeisiin. Kokeissa CaCO3-partikkelit saatiin jauhettua 26 nm kokoon, joka on pienin koskaan aiemmin jauhamalla saavutettu koko CaCO3-partikkeleille
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Bassi, Mitchell Brian 1963. "The mechanism of the ring-opening polymerization of ε-caprolactone using tin(IV) carboxylates." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/291748.

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The polymerization of epsilon-caprolactone using tin(IV) carboxylates has been investigated and related to literature research. Polymers with broad MWD were obtained in quantitative yield. At 100% conversion polymer molecular weights ranged from 50,000 to almost 60,000. After an initial induction period, the polymerization shows zero order kinetics with respect to monomer and near first order kinetics with respect to catalyst. The mechanism of the polymerization is coordination-type, and is dependent on the presence of water or an alcoholic initiator. Added water decreases polymer molecular weight to approx. 30,000 at 100% conversion. The polymer has a terminal hydroxyl group and a terminal carboxyl group. The hydroxyl end is the reactive end in propagation. The carboxyl end and free carboxylic acid produced by the hydrolysis of the catalyst are responsible for the induction period.
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Kingdom, Rachel Michele. "Conducting Polymer Matrix Poly(2,2’-Bithiophene) Mercuric Metal Ion Incorporation." Wright State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=wright1259889438.

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Lott, Joseph Robert. "Reversible addition-fragmentation chain-transfer (RAFT) polymerization in grafting polymer chains from TiO₂ nanoparticles /." Online version of thesis, 2006. https://ritdml.rit.edu/dspace/handle/1850/2878.

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Jia, Huiying. "Anodized TiO2 Nanotube Film For Controllable Drug Delivery." Miami University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=miami1376435848.

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Harris, Jeff. "The influence of adsorption layers on percolation characteristics of electrically conducting antimony-tin oxide/PMMA composites." Thesis, Brunel University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363512.

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Post, Anthony William. "Thermal and fatigue testing of fiber reinforced polymer tie connectors used in concrete sandwich walls." [Ames, Iowa : Iowa State University], 2006.

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Hupfeld, Tim [Verfasser], and Stephan [Akademischer Betreuer] Barcikowski. "Nanoparticle-functionalized polymers for laser powder bed fusion / Tim Hupfeld ; Betreuer: Stephan Barcikowski." Duisburg, 2021. http://d-nb.info/1237221455/34.

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Freitas, Jilian Nei de. "Modulo de celulas solares de TiO/2 corante e eletrolito polimerico." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248622.

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Orientador: Marco-Aurelio De Paoli
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-04T22:57:56Z (GMT). No. of bitstreams: 1 Freitas_JilianNeide_M.pdf: 8316699 bytes, checksum: 55e34d22b75f9c9b873f2edbf8cba703 (MD5) Previous issue date: 2005
Resumo: Investigaram-se células solares de TiO2/corante e eletrólito polimérico visando a construção de um módulo de 9 V. O filme de TiO2 depositado sobre substratos de FTO (fIuorine tin oxide) em vidro foi obtido a partir da modificação de uma suspensão comercial do óxido coloidal em água. Para obter um filme com bom desempenho, utilizou-se uma suspensão com 0,45 g mL à qual foi adicionado 33 % (m/m) de polietilenoglicol com massa molar 20000. O eletrólito empregado nas células consistiu de Nal e I2 dissolvidos em poli(óxido de etileno-co-epicloridrina) contendo os co-monômeros na proporção 87:13, respectivamente. A condutividade iônica máxima desse sistema ocorreu para uma concentração de sal de 15 % (m/m) em relação à matriz polimérica; 2,7 x 10 S cm sob umidade < 1,0 ppm e ~ 30°C. Com o objetivo de aumentar a condutividade iônica, adicionou-se g-butirolactona como plastificante, mantendo-se a concentração de sal em relação à massa de polímero. Observou-se um aumento de cerca de uma ordem de grandeza na condutividade iônica e no coeficiente de difusão das espécies eletroativas no eletrólito plastificado. A suspensão de TiO2 e o eletrólito otimizados foram utilizados na preparação de células solares com área ativa de 1,0 e 4,5 cm. As células menores foram irradiadas com uma lâmpada de Xe. Sob 10 mW cm foram obtidas eficiências de conversão de energia de 2-3 %. As células com área ativa maior foram caracterizadas diretamente sob o Sol e apresentaram eficiência média de 0,9 % (às 12 h). Estes dispositivos foram usados na montagem de módulos de16 células conectadas em série, produzindo 9 V de potencial e 183 mW (valor integrado em um dia). Em conclusão este trabalho demonstrou que, é possível construir um módulo com células solares de TiO2/corante preparadas com eletrólito polimérico plastificado. O desempenho do módulo excedeu as expectativas, sendo a estabilidade o principal desafio para permitir a sua futura aplicação em escala comercial.
Abstract: TiO2 dye-sensitized solar cells assembled with polymer electrolyte were investigated aiming at the construction of a 9 V module. The TiO2 film deposited on substrates of FTO (fluorine tin oxide) on glass was obtained through the modification of a colloidal oxide suspension in water . To obtain a film with good performance, a suspension containing 0.45 g mL of TiO2 and 33 wt % of polyethyleneglycol with molar weight of 20000 was employed. The electrolyte consisted of Nal and I2 dissolved in poly(ethylene oxide-co-epichlorydrin) containing the monomers in the molar ratio 87:13. The maximum ionic conductivity for this system occurred for a concentration of salt of 15 wt % in relation to the polymer matrix; 2.7 x 10 S cm under relative humidity lower than 1.0 ppm and 30°C. To increase the ionic conductivity, g-butyrolactone was added to the electrolyte as a plasticizer, maintaining the salt concentration constant in relation to the polymer. The measured ionic conductivity and diffusion coefficient for the plasticized electrolyte were both increased by ca. one order of magnitude. Both, optimized TiO2 suspension and electrolyte, were applied in solar cells assembled with active area of 1.0 or 4.5 cm. The smaller cells were investigated under 10 mW cm irradiation, with a Xe lamp, and the efficiency of energy conversion was 23 %. The larger cells were characterized directly under the Sun with an average efficiency of 0.9 % (at 12:00 h). These were used to assemble a 9 V module by connecting in series 16 cells. The integrated average daily power was 183 mW. In summary, this work demonstrated that it is feasible to assemble a module with dyesensitized solar cells employing a plasticized polymer electrolyte. The performance of the modules exceeded all expectations and their stability is the main challenge to allow a future commercial scale application.
Mestrado
Quimica Inorganica
Mestre em Química
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Hu, Qingchun. "Fabrication and characterization of poly(amide-imides)/TiO₂ nanocomposite gas separation membranes." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-10022008-063009/.

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Stander, Elzet. "Nuwe reaksies van gedeprotoneerde Fischer-tipe karbeenkomplekse." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1222.

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Li, Zhi. "Three-Dimensional Optical Characterization of Heterogeneous Polymer Systems." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5008.

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In order to truly understand the process-property behavior of polymer systems it is essential to identify the three dimensional structure of the materials fabricated. For heterogeneous polymer systems such as nanoparticle filled systems, determination of the three dimensional optical properties are particularly difficult. Such information is essential, however, if the behavior of these systems are to be understood and formalized. The purpose of the present research was to develop methods for measuring the optical characteristics of heterogeneous polymer systems nondestructively, in order to characterize their three dimensional behavior. The thesis contains three parts: Part A: Study of an Oriented Uniformly Distributed System: Stretched Isotactic Polypropylene- nano Carbon Black Films (IPP-CB). Three nondestructive optical methods: optical waveguide coupling, Fourier Transform Infrared (FTIR) spectroscopy and x-ray diffraction, were used to investigate the effect of the carbon black on the phase behavior and orientation of the films. It was found that the carbon black has little effect on the crystal form and crystallinity, but has a significant effect on the three dimensional orientation behavior of the polypropylene in the IPP-CB systems. Part B: Study of a non-Uniformly Distributed System: Compression Molded Poly (Methyl Methacrylate) with Nano Indium Tin Oxide (PMMA-ITO) The PMMA-ITO sample is an un-oriented and non-uniformly mixed system which has a grain structure. A unique Break Point Waveguide Method was developed to deal with this problem. It was found that both the refractive index and the extinction coefficient increased with ITO concentration and the samples were three dimensionally random. Part C: Development of Computational Improvements in System Operations Four methods were developed to improve the accuracy of the waveguide methods. They are the Bootstrap Method, the Two-Line Method, the Big Area Method and the Modified Knee method. In conclusion, the three dimensional optical characteristics of two different kinds of heterogeneous polymer systems, oriented uniformly distributed IPP-CB films and non-uniformly distributed PMMA-ITO composites, are obtained and their structures evaluated. Further, several new methods were developed to improve the accuracy of the current optical waveguide methods.
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Barkhuysen, Shani. "High resolution 195Pt and 119Sn NMR characterization of platinum(II)-tin(II) complexes." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17841.

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Doherty, Walter John. "POLYMER-MEDIATED ELECTROCHEMISTRY IN SOL-GEL THIN FILMS AND SPECTROELECTROCHEMICAL CHARACTERIZATION OF MOLECULAR ADLAYERS ON INDIUM-TIN OXIDE ELECTRODE SURFACES." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1233%5F1%5Fm.pdf&type=application/pdf.

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Smith, Stuart Douglas. "Barrier properties of spray-coated epoxy-graft-acrylic films on tin-plate in corrosive environments." Thesis, Sheffield Hallam University, 1998. http://shura.shu.ac.uk/20375/.

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This thesis describes an investigation of corrosion processes occurring under thin polymeric layers (3 -5 mum) and suggests ways by which the films suppress the onset of corrosion of the bulk metal in corrosive aqueous environments. Synthetic solutions have been developed which replicate pH and conductivity conditions, likely to be found in beverage cans and which have been used to conduct corrosion studies of commercial lacquer systems. Studies carried out highlight the following points: i) The degree and nature of the film cross-linking has a role in the anti-corrosive action of the films. ii) The quantity of iron released into the beverage is much lower than expected when the corrosivity of the solution and the relative thinness of the film are considered. Work carried out indicates a possible means by which the iron might be complexed by the phenolic cross-linker component of the film with evidence having been obtained showing the ease with which phenolic cross-linker/iron complexes can be formed. iv) Optical Emission Glow discharge spectrometry has provided evidence that iron corrosion products are trapped within the polymer matrix. The work has also highlighted a means of accurately determining the film thickness. v) Water permeation across the cured films was followed using infra-red spectroscopy. The amount of water at found to migrate across films of different cross-linking densities was observed to vary with phenolic cross-linker level present vi) Permeation of ions across cured films has been followed with the use of ion selective electrodes. The films have also been shown to be perm-selective towards the diffusion of sodium ions in preference to chloride ions, in aqueous sodium chloride solutions, thus exhibiting a duality in the nature of the coatings towards the constituents of corrosive environments. vi) Alternating Current Impedance spectroscopy, has been used to observe the electrolyte penetration and corrosion initiation processes, in situ. A knowledge of the electrochemical processes occurring for these water-based epoxy-acrylate films during electrolyte penetration, saturation of the film and development of corrosion underneath the film has been obtained.
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Lin, Yijian. "Structure-Property Relationship of Polyolefins Used as Packages and Adhesives." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1290044976.

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Wu, Kecheng. "Anatase TiO2 Nanotubes Electrode in Rechargeable Magnesium Battery: In Situ Infrared Spectroscopy Studies." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1522509011455228.

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Erdmann, Tim [Verfasser], Brigitte [Akademischer Betreuer] [Gutachter] Voit, and Antonio [Gutachter] Facchetti. "High Charge Carrier Mobility Polymers for Organic Transistors / Tim Erdmann ; Gutachter: Brigitte Voit, Antonio Facchetti ; Betreuer: Brigitte Voit." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://d-nb.info/1128036657/34.

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Erikson, Pontus. "The Interaction of Oil and Polymer in the Microporous Polyethylene Film when using a Thermally Induced Phase Separation Process." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-266155.

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The battery separator is a component of the conventional battery that for long has been overlooked. Just because it’s the only inactive component, doesn’t mean it’s any less important for the battery cell. Recent trends point to an immense growth of the electrical vehicle-industry, and by so, also the lithium-ion battery separators market. This is because the lithium-ion battery is the most common battery type in commercial electrical vehicles. In one of the major manufacturing processes of the separator, mineral oil is used, to achieve a porous film. This study aims to evaluate different oils interaction with the polymer resin in the manufacturing process. Since most oils used in the battery separator industry today use paraffin rich oils, oils with different naphthenic content is tested to find correlations between the oils properties and the crystallinity or the porosity. No correlations for either the porosity or the crystallinity could be made to the oil’s properties. The images taken with the SEM was not enhanced enough to study the pores themselves or the pore structure of the films. For future studies it is recommended to collect more data to identify outliers so more accurate values are obtained. The methodology needs to be verified to ensure the procedure is reproducible. For the study of the pores and the pore structure, an FE-SEM should be used to achieve greater quality enhancement images on the surface of the films.
Batteri separatorn är en komponent i det konventionella batteriet som länge har förbisetts. Bara för att den är en inaktiv komponent, betyder inte att den är mindre viktig för battericellens prestation. Trender idag pekar mot en enorm tillväxt inom elbils-industrin, och med det även litium-jon batteriseparatorns marknad. Det är för att litium-jon batteriet är det batteriet som vanligen används kommersiellt idag i elbilar. I en av de två stora industriella tillverkningsprocesserna används olja för att åstadkomma en porös film. Denna studie syftar på att utvärdera olika oljors interaktion med polymeren i denna tillverkningsprocess. Eftersom de flesta batteriseparator-industrier idag använder paraffinrik olja så testas oljor med olika mycket naftalensikt innehåll för att hitta korrelationer mellan oljornas egenskaper och kristalliniteten eller porositeten hos filmerna. Inga korrelationer för porositeten eller kristalliniteten kunde göras till oljornas egenskaper. Bilderna tagna med SEM var ej tillräckligt förstorade för att kunna studera vare sig porstorleken eller porstrukturen hos filmerna. För framtida studier rekommenderas att samla in mer data för att kunna utskilja ”outliers” i datan, för att erhålla mer korrekta värden. Metodiken måste även verifieras för att säkerställa att proceduren är reproducerbar. För att studera porerna och porstrukturen, borde en FE-SEM användas för att få mer förstorade bilder med bättre kvalité på filmernas yta.
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Hoffmann, Sebastian Tim [Verfasser], and Anna [Akademischer Betreuer] Köhler. "Dynamik und Energetik von Triplettexzitonen in konjugierten Polymeren und Molekülen / Sebastian Tim Hoffmann. Betreuer: Anna Köhler." Bayreuth : Universitätsbibliothek Bayreuth, 2012. http://d-nb.info/1022434616/34.

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Kaul, Pankaj B. "Thermal Transport in Tin-Capped Vertically Aligned Carbon Nanotube Composites for Thermal Energy Management." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1383515941.

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Cormier, Daniel. "Repair of Conductive Layer on Carbon Fibre Reinforced Polymer Composite with Cold Gas Dynamic Spray." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33160.

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Carbon fibre reinforced composites are known for their high specific strength-to-weight ratio and are of great interest to the aerospace industry. Incorporating these materials into the fuselage, like in Boeing's 787 "Dreamliner", offers considerable weight reduction which increases flying efficiency, and reduces the cost of flying. In flight, aircraft are often subject to lightning strikes which, in the case of composites, can result in localized melting given the high resistive nature of the material. Aerospace carbon fibre composites often incorporate a metallic mesh or foil within the composite layers to dissipate the electrical charge through the large aircraft. The damage to the aircraft is minimized but not always eliminated. This research aims to elaborate a practical technique to deposit thin layers of conductive material on the surface of aerospace grade composites. Using Cold Gas Dynamic Spray (CGDS), such coatings could be used to repair damaged components. An experimental research approach was used to develop metallic coated composites. Using the CGDS equipment of Centerline (SST-P), specific parameters (such as gas temperature and stagnation pressure) were determined for each type of metallic coating (tin-based & copper-based). The use of bond coats was explored in order to attain the desired coatings. Once optimized, these coatings were evaluated with respect to their corrosive, adhesive, and electrical properties following industry standards.
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Sampaio, Alexandre Botelho. "Efeitos de um enxerto biofuncional e da terapia laser de baixa intensidade em defeitos ósseos induzidos em tíbias de ratos." Botucatu, 2019. http://hdl.handle.net/11449/183393.

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Orientador: Sheila Canevese Rahal
Resumo: O objetivo do estudo foi avaliar os efeitos de um enxerto biofuncional isolado, ou combinado com a terapia laser de baixa intensidade no reparo de defeitos ósseos induzidos em tíbias de ratos. A hipótese foi que a qualidade do reparo ósseo pode ser incrementada a partir da associação destas terapias. Foram utilizados 40 ratos da linhagem Wistar, machos, três meses de idade, com massa corpórea variando entre 250 e 300 g, nos quais foi induzido defeito ósseo circular de 3 mm de diâmetro, nas tíbias direita e esquerda. Os ratos foram divididos, aleatoriamente, em quatro grupos experimentais equitativos: Grupo 1 – controle, Grupo 2 - enxerto biofuncional composto de beta fosfato tricálcico e poli(ácido lático-co-ácido glicólico) (β-TCP/PLGA), Grupo 3 – terapia laser de baixa intensidade, Grupo 4 – enxerto biofuncional composto de β-TCP/PLGA, e terapia laser de baixa intensidade. Os ratos foram submetidos à eutanásia aos 15 dias após a cirurgia. A irradiação laser (Ga-Al-As) foi iniciada no pós-operatório imediato e repetida três vezes por semana, sendo empreagado 6 J de energia em um único ponto sobre a região do defeito. Após a eutanásia, as tíbias direita e esquerda foram removidas, sendo que as tíbias direitas foram designadas para as análises histológicas e as tíbias esquerdas para as análises biomecânicas com ensaio de flexão em três pontos. Estatisticamente o Grupo 4 apresentou o menor escore de infiltrado inflamatório e o maior de tecido ósseo neoformado, sendo o maior esc... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This study aimed to assess the effects of a biofunctional graft alone, or in combination with low-level laser therapy (LLLT) on the repair of tibial bone defect in rats. The hypothesis was that the combination of therapy modalities could increase the quality of bone healing. Forty male Wistar rats, 3 months of age, weighing from 250 g to 300 g were used. A circular bone defect (3 mm diameter) was created in the right and left tibias. The rats were randomly distributed into four equal groups: G1 - control, G2 - biofunctional graft composed of β-tricalcium phosphate and poly(lactic-co-glycolic acid) (βTCP/PLGA), G3 - LLLT, G4 - biofunctional graft composed of β-TCP/PLGA and LLLT. The rats were euthanized on day 15 day after surgery. The LLLT (Ga-AlAs) was performed in the immediate postoperative period and three times per week. The application was at one point with energy 6J. After euthanasia, the right and left tibiae were removed. The right tibias were used for the histological analysis, and the left tibias were used for three-point bending tests. The statistical analysis showed lower inflammatory infiltrate score and higher newlyformed bone tissue in G4, and the higher granulation tissue score in G3. Highest values for maximum rupture force and maximum displacement occurred in G4. In conclusion, biofunctional graft composed of β-TCP/PLGA and LLLT was better in promoting the repair of bone defects induced in rat tibiae compared with each treatment alone, based on the histopat... (Complete abstract click electronic access below)
Doutor
44

Heinrich, Annika C. J. [Verfasser]. "New Synthetic Strategies for Semiconducting Polymers : Incorporation of Tin, Boron and Gold as Metalfunctionalities and Dinucleophile Synthesis / Annika C. J. Heinrich." Kiel : Universitätsbibliothek Kiel, 2018. http://d-nb.info/1169652751/34.

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45

Veselkova, Iuliia. "Gelové polymerní elektrolyty s retardéry hoření." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-319497.

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This graduate work deals with the study and preparation of gel polymer electrolytes with flame retardants for lithium-ion batteries. The theoretical part describes the types of electrolytes, their features, benefits, how they differ and where they are used in detail. The basis of this section is gel electrolytes with flame retardants, to measure their electrical and electrochemical properties. The experimental part deals with the preparation of samples of gel electrolytes with different percentages of flame retardant, where varied species of flame retardants and measuring their electrical conductivity and potential windows. Impedance spectroscopy, cyclic voltammetry and dynamic-analytical thermal analysis were selected as measuring methods.
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Finne, Anna. "Novel Possibilities for Advanced Molecular Structure Design for Polymers and Networks." Doctoral thesis, KTH, Polymerteknologi, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3623.

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Synthetic and degradable polymers are an attractive choicein many areas, since it is possible to control the way in whichthey are manufactured; more specifically, pathways tomanipulate the architecture, the mechanical properties and thedegradation times have been identified. In this work,L-lactide, 1,5-dioxepan-2-one and ε-caprolactone were usedas monomers to synthesize polymers with different architecturesby ring-opening polymerization. By using novel initiators,triblock copolymers, functionalized linear macromonomers andstar-shaped aliphatic polyesters with well-defined structureshave been synthesized. To synthesize triblock copolymers,cyclic germanium initiators were studied. The polymerizationproceeded in a controlled manner although the reaction rateswere low. To introduce functionality into the polymer backbone,functionalized cyclic tin alkoxides were prepared and used asinitiators. During the insertion-coordination polymerization,the initiator fragment consisting mainly of a double bond wasincorporated into the polymer backbone. The double bond wasalso successfully epoxidized and this gave unique possibilitiesof synthesizing graft polymers with precise spacing. Themacromonomer technique is a very effective method for producingwell-defined graft polymers. Spirocyclic tin initiators weresynthesized and used to construct star-shaped polymers. Thestar-shaped polymers were subsequently crosslinked in apolycondensation reaction. These crosslinked structures swelledin water, and swelling tests showed that by changing thestructure of the hydrogel network, the degree of swelling canbe altered. A first evaluation of the surface characteristicsof the linear triblock copolymers was also performed. AFManalysis of the heat-treated surfaces revealed nanometer-scalefibers and tests showed that keratinocytes were able to growand proliferate on these surfaces.
QC 20100602
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Damadzadeh, Behzad, and Hamideh Jabari. "Biodegradable Composites : Processing of thermoplastic polymers for medical applications." Thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-19329.

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Despite the recent development in PLA and PLGA based medical devices, there are still needs to further improve the mechanical performance of bioresorbable medical implants and their bioactivity. This is normally done by optimizing the filler compositions in selected groups ofbiodegradable polymer matrices. In this study, the effects of various filler levels on mechanical strength and thermal properties of PLA and PLGA composites were investigated. Composites containing different dosage of osteoconductive HAp with various particles size (0-5μm, 0-50 μm, nano size), β-TCP, bioactive glass and biodegradable Poly-L-lactide and Polylactide-glycolic acid was manufactured with melt blending, using a twin-screw extruder.The samples were investigated by Differential Scanning Calorimetry (DSC), thermo gravimetric analysis (TGA), Scanning Electron Microscopy (SEM), viscometer, three points bending machine, and Optical Microscopy (OM). The Extruder produced a porous profile. The result from TGA and SEM indicated that there was homogenous filler dispersion in the matrix after compounding.The result from DSC and Viscometer shows that there was some degradation duringcompounding. Mechanical properties of composites were modified by adding filler to matrix. The addition of Bioactive glass, as a filler, increases the degradation of the polymer matrix. The best filler that was applied is 0-5μm and nano HAp. Also in in-vitro degradation part of this thesis work, the effects of calcium phosphate materialsare investigated on degradation process.
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Тульженкова, О. С., М. О. Рокицький, and А. М. Шут. "Теплопровідність полімерних нанокомпозитів системи поліхлортрифторетилен – діоксид олова." Thesis, Сумський державний університет, 2017. http://essuir.sumdu.edu.ua/handle/123456789/64317.

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Завдяки унікальним фізико-хімічним властивостям і значному потенціалу прикладного використання дослідження полімерних нанокомпозитів є актуальним завданням. Серед таких нанокомпозитів високі потенційні можливості для створення матеріалів з високими показниками захисних та поглинаючих властивостей із заданими електро- та теплофізичними властивостями та низьким вмістом нанодисперсних наповнювачів мають полімерні нанокомпозити системи поліхлортрифторетилен (ПХТФЕ) – діоксид олова (SnO2).
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Topuz, Burcu Berna. "Synthesis And Characterization Of Copper Phthalocyanine Deposited Mica Titania Pigment." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611519/index.pdf.

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In the present work, anatase and rutile titanium dioxide (TiO2) coated lustrous mica pigments were prepared by heterogeneous nucleation method. Anatase-rutile phase transformation of the TiO2 on mica substrate was achieved by coating very thin layers of tin (IV) oxide on mica surfaces prior to TiO2 deposition. Muscovite mica, which was used in the experiments was sieved, pre-treated with sodium bicarbonate and decantated before coating process. The surface morphology of mica titania pigments and anatase-rutile phase transformation were investigated by SEM and XRD analyse, respectively. Also, microwave-assisted synthesis of copper phthalocyanine and tetracarboxamide copper phthalocyanine pigments were carried out with phthalic anhydride and trimellitic anhydride precursors, respectively. Molecular structures of these pigments were confirmed by FT-IR and UV-visible spectroscopy analyse. Furthermore, combination pigments were obtained by the process of deposition of copper phthalocyanine pigments on mica-titania pigment substrate in dimethyl formamide solvent. FT-IR analysis and XRD analyse were performed to observe the transformations in the crystal forms of copper phthalocyanines on the substrate. The surface morphologies of copper phthalocyanines on the mica titania pigments were investigated by SEM analysis. Varying amounts of copper phthalocyanines were deposited on the mica surfaces, and nitrogen elemental analysis was performed to determine the amount of copper phthalocyanines. The resulting pigments were incorporated into alkyd based resin to prepare paint samples. L*a*b* values, gloss property, and hardness of the paint samples were determined by color measuring device, gloss meter and hardness measuring device, respectively. The resulting combination pigments obtained in this study showed improved luster, hue, and color intensity. Furthermore, in literature it was reported that these pigments have very high bleed resistance. This can be attributed to large macromolecular structure of copper phthalocyanine on the surface of mica titania pigment that prevents bleeding of the pigment from the paint. Moreover, the paint samples obtained from combination pigments showed higher hardness with respect to the paint sample of the mica titania pigment.
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Thorud, Steinar. "Overganger mellom matematiske representasjoner : En studie om hvordan 1T-elever gjennomfører overgangen fra situasjon til grafiske og algebraiske representasjoner av polynomer." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for matematiske fag, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25106.

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Denne studien bygger på et sosiokulturelt læringssyn. Fokuset for studien har ligget på hvordan 1T-elever gjennomfører overgangen fra situasjon, som er beskrevet ved naturlig språk, til algebraiske og grafiske representasjoner av polynomer. Hensikten med denne oppgaven er å få innsikt i hvordan elevene bruker matematisk kunnskap i arbeidet med overgangene, og å se nærmere på hvordan elever verifiserer at overgangene deres har blitt korrekt utført. En slik innsikt kan forhåpentligvis gjøre det lettere for lærere å tilrettelegge undervisningen, slik at elevene får en kunnskap om de matematiske representasjonene og en forståelse av sammenhengen imellom dem.Studien bygger på en kvalitativ metode, hvor datainnsamlingen er basert på observasjoner og intervjuer. Utvalget i studien er en gruppe på fem elever fra matematikkurset 1T. I observasjonsdelen av datainnsamlingen, som ble gjort ved hjelp videoopptaker, ble utvalget delt inn i to mindre elevgrupper. Begge gruppene gjennomførte en elevundersøkelse som bestod av fire oppgaver som omhandlet hverdagssituasjoner representert gjennom naturlig språk. Målet med oppgavene var å la elevene gjennomføre overganger til både grafiske og algebraiske representasjoner av polynomer. Den andre delen av datainnsamlingen bestod av intervjuer med hver enkelt elev og foregikk dagen etter observasjonen. Her ble det fokusert på oppgavene fra elevarbeidet og egenskaper ved første- og andregradspolynomer. Intervjuene ble tatt opp med lydopptaker. I analysen har det blir brukt den konstant komparative analysemetode, hvor datamaterialet resulterer i et sett med kategorier som har til hensikt å tydeliggjøre funnene i studien. Resultatene fra studien antyder at 1T-elever kan ha vanskeligheter med å tolke enkelte egenskaper ved polynomer representert ved et naturlig språk. Studien viser også at elever mestrer overgangen fra situasjon til lineære grafer og at det dessuten finnes det en variasjon av elevers foretrukne fremgangsmåter ved denne overgangen. Videre viser studien tegn til at overgangen mellom tekst og algebraiske representasjoner er utfordrende for 1T-elever. Avslutningsvis viser studien at 1T-elever kan ha billedlige tolkninger av grafiske representasjoner av andregradspolynomer som omhandler hverdagssituasjoner.
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