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1
Huang, Jianzhong. "Structural relaxation in thin glass fibers /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487780393264909.
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Holmberg, Patrik. "Laser processing of Silica based glass." Doctoral thesis, KTH, Laserfysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-173929.
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The main topic of this thesis work is photosensitivity and photo-structuring of optical fibers and bulk glass. Although research in the field of photosensitivity in glass and optical fibers has been ongoing for more than three decades, the underlying mechanisms are still not well understood. The objective was to gain a better understanding of the photo-response by studying photosensitivity from a thermodynamic perspective, as opposed to established research focusing on point defects and structural changes, and strain and stress in optical fibers. Optical fibers was mainly used for experimental studies for two reasons; first, photosensitivity in fibers is more pronounced and more elusive compared to its bulk counterpart, and secondly, fibers provide a simplified structure to study as they experimentally can be seen as one-dimensional.Initially, ablation experiments on bulk glass were performed using picosecond infrared pulses. With a design cross section of 40x40 μm, straight channels were fabricated on the top (facing incident light) and bottom side of the sample and the resulting geometries were analyzed. The results show a higher sensitivity to experimental parameters for bottom side ablation which was ascribed to material incubation effects. Moreover, on the top side, the resulting geometry has a V-shape, independent of experimental parameters, related to the numerical aperture of the focusing lens, which was ascribed to shadowing effects.After this work, the focus shifted towards optical fibers, UV-induced fiber Bragg gratings (FBGs) and thermal processing with conventional oven and with a CO2 laser as a source of radiant heat.First, a system for CO2 laser heating of optical fibers was constructed. For measuring the temperature of the processed fibers, a special type of FBG with high temperature stability, referred to as "Chemical Composition Grating" (CCG) was used. A thorough characterization and temperature calibration was performed and the results show the temperature dynamics with a temporal resolution of less than one millisecond. The temperature profile of the fiber and the laser beam intensity profile could be measured with a spatial resolution limited by the grating length and diameter of the fiber. Temperatures as high as ~ 1750 °C could be measured with corresponding heating and cooling rates of 10.500 K/s and 6.500 K/s.Subsequently, a thorough investigation of annealing and thermal regeneration of FBGs in standard telecommunication fibers was performed. The results show that thermal grating regeneration involves several mechanisms. For strong regeneration, an optimum annealing temperature near 900 C was found. Two different activation energies could be extracted from an Arrhenius of index modulation and Braggv iwavelength, having a crossing point also around 900 °C, indication a balance of two opposing mechanisms.Finally, the thermal dynamics and spectral evolution during formation of long period fiber gratings (LPGs) were investigated. The gratings were fabricated using the CO2 laser system by periodically grooving the fibers by thermal ablation. Transmission losses were reduced by carefully selecting the proper processing conditions. These parameters were identified by mapping groove depth and transmission loss to laser intensity and exposure time.Huvudtemana i denna avhandling är fotokänslighet och fotostrukturering av optiska fibrer och bulk glas. Trots att forskning inom fotokänslighet i glas och optiska fibrer har pågått under mer än tre decennier är de bakomliggande mekanismerna ännu inte klarlagda. Syftet var att få en bättre förståelse för fotoresponsen genom att studera fotokäsligheten ur ett termodynamiskt perspektiv, i motsats till etablerad forskning med fokus på punktdefekter och strukturförändringar, samt mekaniska spännings effekter i optiska fibrer. Optiska fibrer användes för flertalet av de experimentella studierna av två skäl; för det första är fotokänsligheten i fibrer större och dessutom vet man mindre om bakomliggande mekanismer jämfört med motsvarande bulk glas, och för det andra kan fibrer vara enklare att studera eftersom de experimentellt kan ses som en endimensionell struktur.Inledningsvis utfördes ablaherings experiment på bulk glas med en infraröd laser med pikosekund pulser. Raka kanaler med ett designtvärsnitt på 40x40 μm tillverkades på ovansidan (mot infallande ljus) och bottensidan av provet och de resulterande geometrierna analyserades. Resultaten visar en högre känslighet för variationer i experimentella parametrar vid ablahering på undersidan vilket kan förklaras av inkubations effekter i materialet. Dessutom är den resulterande geometrin på ovansidan V-formad, oavsett experimentella parametrar, vilket kunde relateras till den numeriska aperturen hos den fokuserande linsen, vilket förklaras av skuggningseffekter.Efter detta arbete flyttades fokus mot optiska fibrer, UV inducerade fiber Bragg gitter (FBG), och termisk bearbetning med konventionell ugn samt även med en CO2-laser som källa för strålningsvärme.Först konstruerades ett system för CO2-laservärmning av fibrer. För mätning av temperaturen hos bearbetade fibrer användes en speciell sorts FBG med hög temperaturstabilitet, kallade ”Chemical Composition Gratings” (CCG). En grundlig karaktärisering och temperaturkalibrering utfördes och temperaturdynamiken mättes med en tidsupplösning på under en millisekund. Temperaturprofilen i fibern, och laserns strålprofil, kunde mätas med en spatiell upplösning begränsad av gitterlängden och fiberns diameter. Temperaturer upp till ~1750 °C, vilket är högre än mjukpunktstemperaturen, kunde mätas med korresponderande uppvärmnings- och avsvalningshastighet på 10.500 K/s och 6.500 K/s.Därefter gjordes en omfattande undersökning av värmebearbetning och termisk regenerering av FBG:er i telekomfiber. Resultaten visar att termisk gitter-regenerering aktiveras av flera olika mekanismer. Värmebearbetning vid en temperatur omkring 900 °C resulterade i starka gitter efter en regenerering vid en temperatur på 1100 °C. Två olika aktiveringsenergier kunde extraheras från en Arrhenius plot avseende brytningsindexmodulation och Braggvåglängd, med en skärningspunkt tillika runt 900 °C, vilket indikerar en avvägning mellan två motverkande mekanismer vid denna temperatur.Slutligen undersöktes temperaturdynamiken och de spektrala egenskaperna under tillverkning av långperiodiga fibergitter (LPG). Gittren tillverkades med CO2-vi iilasersystemet genom att skapa en periodisk urgröpning medelst termisk ablahering. Transmissionsförluster kunde reduceras med noggrant valda processparametrar. Dessa parametrar identifierades genom mätningar av ablaherat djup och transmissionsförlust som funktion av laserintensitet och exponeringstid.
QC 20150924
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Shi, Jiawanjun. "Properties of alkaline-resistant calcium-iron-phosphate glasses." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.umr.edu/thesis/pdf/Shi_09007dcc8043f8f6.pdf.
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Thesis (M.S.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 25, 2008) Includes bibliographical references (p. 52-54).
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Abu-Zahra, Esam. "High Strength E-Glass/CNF Fibers Nanocomposite." Cleveland State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=csu1198878550.
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Jin, Kun. "Processing characteristics and properites [sic] of glass fiber reinforced composites from post consumer carpets." Thesis, Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04062004-164643/unrestricted/jin%5Fkun%5F200312%5Fms.pdf.
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Kuo, Chai-Pei. "Characterization of photoinduced gratings in optical glass fibers." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184515.
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The properties of photo-induced gratings in germania doped glass fibers were studied. Permanent phase gratings in a fiber core were fabricated by the mixing of two contra propagating waves. Experiments are described and results are presented which show that the strength of a photoinduced grating is strongly dependent on the writing power as well as the laser writing wavelength. A rigorous development of linear coupled mode theory for the contra propagation geometry is given and used to model the experimentally observed grating responses as a function of fine tuning frequency of probing light. Measurements have been done of the amplitude and phase response of the grating structure and compared with theoretical models of uniform and chirped gratings. The theoretically predicted negative group velocity dispersion in fiber grating was observed interferometrically and described in detail. The nonlinear coupled mode theory has been fully implemented in a computer program and some numerical results are given in the second part of this thesis. The dynamics of a pulse propagating in the fiber grating is simulated and the results show its dependence on pulse energy, frequency detuning, and the type of grating geometry. A limitation is found in the dispersion property of a constant amplitude fiber grating so that the pulse compression ratio and the width of a compressible pulse is strictly limited to ≅250 picoseconds.
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Cheung, Wai-lam, and 張惠林. "The interfacial properties of glass fibre reinforced polypropylene." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1990. http://hub.hku.hk/bib/B31231792.
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Cheung, Wai-lam. "The interfacial properties of glass fibre reinforced polypropylene /." [Hong Kong] : University of Hong Kong, 1990. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12718634.
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Kim, Jong-Kook. "Investigation of High-Nonlinearity Glass Fibers for Potential Applications in Ultrafast Nonlinear Fiber Devices." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/28569.
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Nonlinear fiber devices have been attracting considerable attention in recent years, due to their inherent ultrafast response time and potential applications in optical communication systems. They usually require long fibers to generate sufficient nonlinear phase shifts, since nonlinearities of conventional silica-core silica-clad fibers are too low. These long devices, however, cause the serious problems of pulse walk-off, pulse broadening, and polarization fluctuation which are major limiting factors for response time, switching bandwidth, and maximum transmittable bit-rate. Therefore, short device length is indispensable for achieving ultrafast switching and higher bit-rate data transmission.
To shorten the required device length, fiber nonlinearities should be increased. In this dissertation, as a way of increasing fiber nonlinearities, high-nonlinearity materials of Litharge, Bismite, Tellurite, and Chalcogenide glasses have been considered. Although they have high nonlinearities, they also have high group-velocity dispersion and high losses deteriorating the performance of nonlinear fiber devices seriously. The aim of this work is to investigate how these high-nonlinearity glasses affect the performance of nonlinear fiber devices, taking into consideration both the advantages and disadvantages. To achieve it, the critical properties of various nonlinear fiber devices constructed with the different types of high-nonlinearity glasses and different types of fibers have been evaluated.
It turned out that the required device lengths of nonlinear fiber devices constructed with the high-nonlinearity glasses were significantly reduced and high group-velocity dispersions and losses could not be major problems due to the extremely short device length. As a result, it would be possible to suppress the problems of pulse walk-off, pulse broadening, and polarization fluctuation in nonlinear fiber devices by introducing high-nonlinearity glasses, thus enabling ultrafast switching and higher bit-rate data transmission.
Furthermore, in this dissertation, a new scheme of wavelength-division demultiplexing based on the optical Kerr effect has been proposed for the first time. The new scheme can turn the disadvantage of the extremely high group-velocity dispersion of high-nonlinearity glasses into an advantage of wavelength-division demultiplexing. Finally, it now would be possible to greatly increase maximum transmittable bit-rate in optical communication systems by simultaneously demultiplexing optical time-division-multiplexed signals and wavelength-division-multiplexed signals with an optical Kerr effect-based demultiplexer.Ph. D.
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Groulx, Jean-Guy Joseph Carleton University Dissertation Engineering Civil and Environmental. "Investigation of wood flexural members reinforced with glass fibers." Ottawa, 1995.
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Mahmood, Haroon. "Multifunctionality in epoxy/glass fibers composites with graphene interphase." Doctoral thesis, Università degli studi di Trento, 2017. https://hdl.handle.net/11572/368851.
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In this project, the synergetic effect of a graphene interphase in epoxy/glass fibers composites was investigated by coating glass fibers (GF) with graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets by an electrophoretic deposition (EPD) technique. Graphite oxide was prepared using modified Hummers method in which raw graphite powder was oxidized using potassium permanganate (KMnO4) in acidic solution. Using ultrasonic technique, the graphite oxide was dispersed homogenously in water to create a stable GO suspension which was used as a bath in the EPD process. For the coating process, two copper plates were used as electrodes in the EPD process in which GF were placed in front of anode for GO deposition since GO tends to carry negative charges due to oxygen functional groups attached on the graphene structure as produced in the modified Hummers method. The deposition was carried out at different applied fields while maintaining the dispersion concentration and deposition time constant. This process produced GF coated with GO nanosheets, while to obtain GF coated with rGO, GO coated fibers were subjected to chemical reduction process where the fibers were placed in an environment of hydrazine hydrate which reduced the GO coating on GF. Through this step, rGO coated GF were obtained. The oxidation level of GO and rGO was evaluated using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron (XPS) spectroscopy techniques which confirmed the successful oxidation of graphite powder into graphite oxide due to liquid chemical oxidation process while the hydrazine reduction method reduced the oxygen amount from 34% to 10% in GO hence converting it into rGO. Scanning electron microscopy analysis of coated fibers revealed uniform coating of GF with GO and rGO where the amount of deposition increased with increased applied field.
The effect of GO or rGO coating on GF obtained by EPD process was first evaluated by determining the adhesion between GF and epoxy matrix. Single fiber fragmentation test was utilized to determine the interfacial shear strength (ISS) between the uncoated or coated fibers and epoxy matrix. Single fiber epoxy composites were prepared by using GO and rGO coated fibers and were tested using a mini-tensile testing machine and monitoring the lengths of fragments of fibers obtained during the tensile test. It was observed that in case of GO coated fibers, the ISS increased by 218% in comparison to uncoated fiber based composite. The increase of interfacial adhesion in this case, it can be attributed to the fact that GO carries oxygen functional groups which creates physical and chemical bonding between both the GF surface and the epoxy matrix. For investigating the interactions between GF and GO, atomic force microscopy (AFM) was used to determine the interfacial adhesion between them by scratching GO on GF. It was proved that the delamination strength was higher than the ISS, hence proving the efficacy of the selected GO deposition method. On the other hand, single fiber fragmentation tests indicated a 70% increase in ISS for rGO coated GF when embedded in the epoxy matrix as compared to uncoated fibers. This increment is lower than that observed for GO coated fibers and it has been attributed to the fact that rGO does not possess enough oxygen based functional groups to efficiently interact with the polymer matrix. The observed increase in ISS with respect to uncoated GF is based on the frictional forces offered by the roughness of rGO nanosheets. This confirms that the presence of an interphase (either GO or rGO) creates favorable load transfer mechanism through either chemical or physical bonding or even both depending on the nature of the interphase. To test further the positive effect of GO based interphase in epoxy/glass composites in terms of mechanical reinforcement, multifiber (uncoated and GO or rGO coated) reinforced epoxy composites were created by hand lay-up method. Laminas of fibers were wetted by epoxy resin and stacked over one another in certain number depending on the thickness of the resultant composite. These composites were subjected to various mechanical tests, such as flexural tests, short-beam shear tests, mode I interlaminar fracture toughness and creep tests which also confirmed that GO and rGO based interphase in epoxy/glass composites increase the performances of the composite with respect to that of the uncoated GF based composites. GO proved to be the best interphase in terms of mechanical properties obtained, as proved before. The multifunctionality of such interphases based on graphene was analyzed and confirmed using multiple tests on epoxy/glass composites containing uncoated and coated (GO or rGO). In particular, the electrical and thermal conductivity of the composites were tested in which the composites based on rGO interphase showed the highest conductivity which not only confirms that rGO coated fibers in epoxy/glass composites render the composites conductive but also proves the successful chemical reduction process used in this work.
These conductive composites were subjected to piezoresistivity tests in which the applied longitudinal strain in different modes resulted in change in resistance thus showing a possibility of using such composites as strain sensing devices or for structural health monitoring purposes in automotive or aerospace applications.
These conductive composite specimens were also analyzed for their dielectric properties. The tests showed increased permittivity values as compared to both uncoated and GO coated composites thus revealing the possibility to use composites containing rGO coated fibers for electromagnetic interference shielding applications.
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Mahmood, Haroon. "Multifunctionality in epoxy/glass fibers composites with graphene interphase." Doctoral thesis, University of Trento, 2017. http://eprints-phd.biblio.unitn.it/2077/1/Thesis_draft_(Final)_-_7_HM.pdf.
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In this project, the synergetic effect of a graphene interphase in epoxy/glass fibers composites was investigated by coating glass fibers (GF) with graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets by an electrophoretic deposition (EPD) technique. Graphite oxide was prepared using modified Hummers method in which raw graphite powder was oxidized using potassium permanganate (KMnO4) in acidic solution. Using ultrasonic technique, the graphite oxide was dispersed homogenously in water to create a stable GO suspension which was used as a bath in the EPD process. For the coating process, two copper plates were used as electrodes in the EPD process in which GF were placed in front of anode for GO deposition since GO tends to carry negative charges due to oxygen functional groups attached on the graphene structure as produced in the modified Hummers method. The deposition was carried out at different applied fields while maintaining the dispersion concentration and deposition time constant. This process produced GF coated with GO nanosheets, while to obtain GF coated with rGO, GO coated fibers were subjected to chemical reduction process where the fibers were placed in an environment of hydrazine hydrate which reduced the GO coating on GF. Through this step, rGO coated GF were obtained. The oxidation level of GO and rGO was evaluated using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron (XPS) spectroscopy techniques which confirmed the successful oxidation of graphite powder into graphite oxide due to liquid chemical oxidation process while the hydrazine reduction method reduced the oxygen amount from 34% to 10% in GO hence converting it into rGO. Scanning electron microscopy analysis of coated fibers revealed uniform coating of GF with GO and rGO where the amount of deposition increased with increased applied field.
The effect of GO or rGO coating on GF obtained by EPD process was first evaluated by determining the adhesion between GF and epoxy matrix. Single fiber fragmentation test was utilized to determine the interfacial shear strength (ISS) between the uncoated or coated fibers and epoxy matrix. Single fiber epoxy composites were prepared by using GO and rGO coated fibers and were tested using a mini-tensile testing machine and monitoring the lengths of fragments of fibers obtained during the tensile test. It was observed that in case of GO coated fibers, the ISS increased by 218% in comparison to uncoated fiber based composite. The increase of interfacial adhesion in this case, it can be attributed to the fact that GO carries oxygen functional groups which creates physical and chemical bonding between both the GF surface and the epoxy matrix. For investigating the interactions between GF and GO, atomic force microscopy (AFM) was used to determine the interfacial adhesion between them by scratching GO on GF. It was proved that the delamination strength was higher than the ISS, hence proving the efficacy of the selected GO deposition method. On the other hand, single fiber fragmentation tests indicated a 70% increase in ISS for rGO coated GF when embedded in the epoxy matrix as compared to uncoated fibers. This increment is lower than that observed for GO coated fibers and it has been attributed to the fact that rGO does not possess enough oxygen based functional groups to efficiently interact with the polymer matrix. The observed increase in ISS with respect to uncoated GF is based on the frictional forces offered by the roughness of rGO nanosheets. This confirms that the presence of an interphase (either GO or rGO) creates favorable load transfer mechanism through either chemical or physical bonding or even both depending on the nature of the interphase. To test further the positive effect of GO based interphase in epoxy/glass composites in terms of mechanical reinforcement, multifiber (uncoated and GO or rGO coated) reinforced epoxy composites were created by hand lay-up method. Laminas of fibers were wetted by epoxy resin and stacked over one another in certain number depending on the thickness of the resultant composite. These composites were subjected to various mechanical tests, such as flexural tests, short-beam shear tests, mode I interlaminar fracture toughness and creep tests which also confirmed that GO and rGO based interphase in epoxy/glass composites increase the performances of the composite with respect to that of the uncoated GF based composites. GO proved to be the best interphase in terms of mechanical properties obtained, as proved before. The multifunctionality of such interphases based on graphene was analyzed and confirmed using multiple tests on epoxy/glass composites containing uncoated and coated (GO or rGO). In particular, the electrical and thermal conductivity of the composites were tested in which the composites based on rGO interphase showed the highest conductivity which not only confirms that rGO coated fibers in epoxy/glass composites render the composites conductive but also proves the successful chemical reduction process used in this work.
These conductive composites were subjected to piezoresistivity tests in which the applied longitudinal strain in different modes resulted in change in resistance thus showing a possibility of using such composites as strain sensing devices or for structural health monitoring purposes in automotive or aerospace applications.
These conductive composite specimens were also analyzed for their dielectric properties. The tests showed increased permittivity values as compared to both uncoated and GO coated composites thus revealing the possibility to use composites containing rGO coated fibers for electromagnetic interference shielding applications.
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Hofmann, John. "Extension of the Method of Ellipses to Determining the Orientation of Long, Semi-flexible Fibers in Model 2- and 3-dimensional Geometries." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/23921.
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The use of fiber-reinforced polymer composites formed via injection molding is of increasing interest due to their superior mechanical properties as compared to those of the polymer matrix alone. These mechanical properties, however, are strongly dependent on the fiber length and orientation distributions within a molded part. As such, there is a need to understand and model the orientation evolution of chopped fibers in flow in order to accurately simulate the final fiber orientation distribution within injection molded parts. As a result of this, accurate and reliable experimental measurement of fiber orientation is needed.
Within this research, the application and validity of the Method of Ellipses for determining the orientation of long, semi-flexible glass fibers within injection molded composites has been investigated. A fiber suspension with an average length of approximately 3.9 mm was the focus of this study and assumed to be representative of commercial distributions. A novel method to quantify fiber curvature was developed and utilized to show that flexibility in center-gated disc and the end-gated plaque samples was minimal on average for the selected fiber length distribution. Thus, it was determined that the Method of Ellipses was applicable when utilized to obtain reliable orientation data for the selected long glass fiber suspension and within the chosen geometries that exhibit 1-, 2-, and 3-dimensional velocity fields. However, a modified image analysis width was found to be necessary in regions of highly aligned fibers, due to the increase in ellipse size and the need to reduce the number of partial objects and thus minimize error. This allowed for a direct comparison of the experimental orientation behavior of short and long glass fibers within the center-gated disc and the end-gated plaque, as well as the effect of the orientation distributions on the global modulus of the part.Ph. D.
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Kneis, Christian. "Investigation of mid-infrared supercontinuum generation in soft-glass fibers from a Q-switched mode-locked 2 mm fiber laser." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0135/document.
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Cette thèse est dédiée à l’étude de la génération de supercontinuum (SCG) deforte puissance moyenne dans le domaine spectral entre 2 mm et 5,5 mm. Un laser à fibredopée thulium (Tm3+) opérant dans un régime simultanément déclenché et à verrouillage demodes (QML) a été développé. En régime continu ce laser a délivré 70 W et en régime QML,26Wmoyens ont été obtenus pour des taux de répétition en QS de 180 kHz ou plus. L’énergiela plus élevée contenue dans une enveloppe QS a été évaluée à 166 mJ avec 66 mJ contenuedans la sous-impulsion à verrouillage de mode la plus énergétique. L’émission du laser àfibre correspondait toujours à un facteur de qualité M2 excellent, entre 1,1 et 1,2. La SCGcouvrant la plage spectrale de 2 mm à 5,5 mm a été réalisée en implémentant différentes fibresen cascade. Des supercontinua jusqu’à environ 4 mm ont été générés dans des fibres en fluorurepuis pour la plage spectrale complémentaire entre 4 mm et 5,5 mm, des fibres en chalcogénureont été utilisées.La puissance moyenne maximale de 7,8 W a été démontrée pour un supercontinuum dans unefibre en ZBLAN. Le spectre s’étend jusqu’à 4,2 mm. Au total, 69%/43%/30%/16,5% de lapuissance totale ont été mesurés au-delà de 2,15 mm/2,65 mm/3,1 mm/3,5 mm respectivement.La fibre en InF3 a permis d’atteindre une puissance moyenne de 0,8 W et le supercontinuums’étend jusqu’à 2,95 mm.Pour les essais d’élargissement spectral complémentaire, trois fibres en chalcogénure ont étéutilisées. L’élargissement spectral a été démontré pour toutes les fibres en chalcogénure.Jusqu’à 20 mW de puissance ont été obtenus avec une fibre As2Se3. Le spectre a été étendujusqu’à 4,9 mmThis thesis reports about the investigation of high power supercontinuum (SC)generation between 2 mm and 5.5 mm. A Q-switched mode-locked (QML) thulium (Tm3+)-doped fiber laser has been developped to pump different nonlinear fibers. The fiber laserprovided in continuous wave regime an output power of 70 W. In QML operation, 26 W havebeen obtained with Q-switched repetition rates of 180 kHz or higher. The highest energy of theQS envelopes has been 166 mJ with 66 mJ contained in the most-energetic ML pulses, whichhave been surrounded by Gaussian-like pedestals with temporal widths around 2.5 ns. On topof these pedestals, very short temporal peaks with pulse durations around 15 ps appeared. Thehighest achieved peak power of a pedestal has been 25 kW. The beam parameter product M2of the fiber laser has been measured in different operational regimes and resulted always in anexcellent value around 1.2.The highest SC output power level from a ZBLAN fiber has been 7.8 W. In total, 69%/43%/30%/16.5% of the transmitted SC output radiation could be converted beyond the wavelengthof 2.15 mm/2.65 mm/3.1 mm/3.5 mm, respectively, with the broadest output spectrum from theZBLAN fiber exceeding 4.2 mm. The InF3 fiber provided a total output power of 0.8 W withan output spectrum up to 2.95 mm.Successful broadening of the wavelength-limited SC output from the ZBLAN fibers has beenachieved with all three investigated chalcogenide fibers with as much as 20 mW of outputpower by using an arsenic selenide fiber. The output spectrum exceeded 4.9 mm
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Pustilnik, Leslie Royce 1964. "The pulmonary inflammatory and fibrotic response induced by glass fibers." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276624.
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The present study was initiated to evaluate the pulmonary inflammatory and fibrotic responses induced by single and repeated exposures to glass fibers. Single and repeated intratracheal injections of glass fibers induced an acute inflammatory response which progressed to a chronic inflammatory and fibrotic response. Mice exposed to glass fibers in single or repeated doses demonstrated elevated numbers of eosinophils, neutrophils and macrophages and increases in cell-free protein in lung lavage fluid at five days post-exposure. These parameters, in addition to relative lung/body weight ratios and lung tissue hydroxyproline levels, were elevated in comparison to saline control animals at five weeks post-exposure. Although repeated exposures to glass fibers did not potentiate the cellular inflammatory response, they did induce a marked infiltration of eosinophils, a response not observed with either asbestos or silica exposures. These observations suggest that glass fibers may be more toxic to the lungs than previously thought.
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Watts, Jeremy S. "Modeling the fiberglass spinning process." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5197.
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Thesis (M.S.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains vii, 92 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 73-74).
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Constantinou, Marios, and Michael Gehde. "Infrared Welding of Continuous Glass Fiber-Reinforced Thermoplastics – Approaches to use the Fibers in the Joint." Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21293.
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Thermoplastic prepregs that are also known as organo sheets are processed in presses and formed to half shells. Larger components can be produced by joining the half shells, which results in hollow bodies. However, current manufacturing technologies allow only cap profile shaped joints, which cause fiber deflections in the joint plane. This paper shows that overlapping infrared welds in organo sheets enable weld strengths close to the interlaminar shear strengths of the unwelded materials and thus a fiber utilization across the joint plane. By using high welding pressures, a matrix depletion and a change of the fiber alignment in the weld plane may occur which causes low weld strengths. Therefore, criteria for the successful welding were defined and various possibilities to optimize the weld strengths were investigated.
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Velez-Garcia, Gregorio Manuel. "Experimental Evaluation and Simulations of Fiber Orientation in Injection Molding of Polymers Containing Short Glass Fibers." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/27335.
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Injection molded short fiber reinforced composites have generated commercial interest in the manufacturing of lightweight parts used in semi-structural applications. Predicting these materials’ fiber orientation with quantitative accuracy is crucial for technological advancement, but the task is difficult because of the effect of inter-particle interactions at high concentrations of fiber found in parts of commercial interest.
A complete sample preparation procedure was developed to obtain optical micrographs with optimal definition of elliptical and non-elliptical footprint borders. Two novel aspects in this procedure were the use of tridimensional markers to identify specific locations for analysis and the use of controlled-etching to produce small shadows where fibers recede into the matrix. These images were used to measure fiber orientation with a customized image analysis tool. This tool contains several modifications that we introduced in the method of ellipses which allow us to determine tridimensional fiber orientation and to obtain measurements in regions with fast changes in orientation. The tool uses the location of the shadow to eliminate the ambiguity problem in orientation and characterizes non-elliptical footprints to obtain the orientation in small sampling areas.
Cavitywise measurements in two thin center-gated disks showed the existence of an asymmetric profile of orientation at the gate and an orientation profile that washed out gradually at the entry region until disappearing at about 32 gap widths. This data was used to assess the prediction of cavitywise orientation using a delay model for fiber orientation with model parameters obtained from rheometrical experiments. Model predictions combining slip correction and experimentally determined orientation at the gate are in agreement with experimental data for the core layers near the end-of-fill region.
Radialwise measurements of orientation at the shell, transition and core layer, and microtextural description of the advancing front are included in this dissertation. The analysis and assessment of the radial evolution of fiber orientation and advancing front based on comparing the experimental data with simulation results are under ongoing investigation.Ph. D.
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Corsino, Betsy Ann 1962. "THE PULMONARY RESPONSE INDUCED BY GLASS FIBERS (INFLAMMATION, SILICOSIS, MURINE MODEL)." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/291468.
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Miller, Leah Margaret. "Characterization of extended chain polyethylene/S-2 glass, interply hybrid, fabric composites." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/8623.
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Taniguchi, Shinro. "Measurement of the through-thickness strength of composites." Thesis, University of Oxford, 1998. http://ora.ox.ac.uk/objects/uuid:441ed7e2-72ed-4c2e-b0d2-066b5419b56e.
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This research deals with the mechanical characterisation of thick composite laminates in the through-thickness direction. Three independent glass fibre/epoxy laminate configurations, namely cross, quasi-isotropic, and woven, plies were investigated. Six specimen configurations, of which two were developed herein, were employed in order to determine the strength behaviour of these three laminate configurations when subjected to interlaminar shear and interlaminar tensile stresses in isolation and in combination. The stress and strain distributions were estimated using the ABAQUS FEA package. The strain distribution obtained thereby was verified experimentally via Moirandeacute; interferometry which records the exact strain field at the test section. A two dimensional failure envelope is defined for each laminate configuration using the experimentally obtained data. All three independent laminate configurations exhibited almost identical failure envelopes. The woven laminate exhibited superior interlaminar shear strength when subjected to combined interlaminar shear and interlaminar tensile stresses, whereas the cross-ply laminate exhibited superior interlaminar tensile strength when subjected to the same combination of stress. The characteristics of the quasi-isotropic laminate were similar to that of the cross-ply laminate. A partial three dimensional failure envelope was also defined for the materials tested.
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Heyl, Hanna Verena. "Phase Relations in the YBa2Cu3O7-x - SiO2 System and the Impact on Superconducting Fibers." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/95058.
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This dissertation presents the first reported identification and analyses of the phase relations in the YBa2Cu3O7-x (YBCO)-SiO2 system at elevated temperatures. In this regard, a rigorous characterization study of the reaction phases within YBCO glass fibers, heat-treated YBCO+SiO2 pellets, rapid thermally annealed YBCO+SiO2 rods and rapid thermally annealed YBCO powder inside a fused silica tube is provided. These analyses are based on a vast set of generated novel results obtained using energy dispersive spectroscopy analyses on an environmental scanning electron microscope, X-Ray diffraction analyses, Raman spectroscopy, X-ray photoelectron spectroscopy analyses and a cross-polarized light study.
First, original drawings of YBCO into glass fibers using the molten-core approach on a fiber draw tower in air and oxygen atmospheres are presented and analyzed. The performed analyses reveal the occurrence of reactions between the YBCO core and the silica cladding in as-drawn fibers as well as after additional heat-treatments. A detailed analysis and characterization of the occurring dissolution and diffusion based reaction processes is, then, provided along with the identification of the arising phase separation. Moreover, in order to analyze drawing YBCO glass fibers at lower temperatures, the use of borosilicate as the preform material is also investigated.
This varied set of experiments and associated analyses reveal that the as-drawn YBCO fibers contain an amorphous core and that cuprite (Cu2O) is the first phase to crystallize out of the amorphous silicate matrix upon heat-treatment. Furthermore, the obtained results demonstrate the dissolution of the fused silica cladding into Si4+ and O2- ions and their subsequent diffusion into the molten YBCO core, leading to phase separation due to an occurring miscibility gap in the YBCO-SiO2 system as well as to silicate formation and amorphization of the YBCO core. This, as a result, prohibits the formation of the superconductive YBCO (Y-123) phase upon annealing. In addition, heat-treatment analyses show that higher temperatures or prolonged dwelling times at lower temperatures lead to the formation of barium copper and yttrium barium silicates. The analysis focusing on the use of borosilicate as the preform material reveals that drawing at lower temperatures reduces the dissolution and diffusion based reactions, but does not prevent them. Furthermore, the analysis on YBCO glass fibers with a fused silica cladding drawn in oxygen atmosphere shows that a higher oxygen content increases the dissolution of the fused silica cladding into its ions and their subsequent diffusion into the molten YBCO core.
In addition, the performed heat-treatments on YBCO+SiO2 pellets in air and oxygen atmospheres demonstrate the gradual decomposition of the Y-123 phase with an increase in SiO2 content. Moreover, the rapid thermal annealing experiments with a subsequent quenching step on YBCO+SiO2 rods and on YBCO powder inserted inside a fused silica tube show the decomposition of the Y-123 phase and the formation of phases similar to the phases obtained in the YBCO glass fiber study, thus corroborating the results thereof.
In summary, this dissertation enables the determination of the phase relations and reaction processes within the YBCO-SiO2 system, the identification of the direct effects of the silicon content on the Y-123 phase decomposition, as well as a rigorous characterization of the dissolution and diffusion based reactions within the YBCO-SiO2 glass-clad fiber system. The generated results and drawn conclusions build a fundamental understanding of phase relations in the YBCO-SiO2 system, which enables a definite assessment of the feasibility of manufacturing long-scale purely superconductive YBCO glass fibers using the molten-core approach and introduces advanced contributions to general glass-clad fiber systems manufactured using this method.Doctor of Philosophy
This dissertation provides the first reported identification and analysis of the phase relations in the YBa2Cu3O7-x (YBCO)-SiO2 system at high temperatures. In this regard, a thorough characterization study of the reaction phases within YBCO glass fibers drawn using the molten-core approach on a fiber draw tower is provided. In addition, heat-treatment analyses considering YBCO+SiO2 pellets, rapid thermally annealed YBCO+SiO2 rods and rapid thermally annealed YBCO powder inside a fused silica tube are performed to gain further fundamental insights. The performed analyses are based on a wide set of characterization methods including energy dispersive spectroscopy on an environmental scanning electron microscope, X-Ray diffraction analyses, Raman spectroscopy, X-ray photoelectron spectroscopy and a cross-polarized light study. Our experimental results and performed analyses identify the phase relations and reaction processes within the YBCO-SiO2 system at elevated temperatures, demonstrate the direct effects of the silicon content on the superconductive YBCO phase decomposition, enable drawing definite conclusions regarding the feasibility of manufacturing long-scale purely superconductive YBCO glass fibers using the molten-core approach, and, characterize the dissolution and diffusion based reactions occurring within the YBCO-SiO2 glass-clad fiber system. In a nutshell, this dissertation provides a fundamental understanding of phase relations in the YBCO-SiO2 glass-clad system as well as key insights covering general glass-clad fibers drawn using the molten-core approach, paving the way for improved glass-clad fiber manufacturing using this method.
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DeBenedictis, Mach Austin. "Glass fiber / polypropylene prepregs produced by electrostatic fluidized bed powder fusion coating." Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/11190.
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Sweetland, Matthew 1970. "Nozzle analysis and heat transfer model for spray cooling of glass fibers." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9915.
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LOPEZ, ISCOA PABLO. "Design, processing and characterization of glass fibers and coatings for healthcare industries." Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2725389.
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In this PhD, several bioactive phosphate glasses doped with erbium ions (Er3+) were synthesized and characterized in order to develop new bioactive fiber sensors for medical diagnostics and therapeutics in healthcare applications.
Firstly, Er3+-doped phosphate glasses within the glass system P2O5-SrO-Na2O were fabricated using the melt-quenching technique. The glasses were prepared with different compositions and analyzed to understand the impact of the addition of Al2O3, TiO2 or ZnO on the thermal, structural and luminescence properties of the glasses. The results showed that with the addition of Al2O3 and TiO2 the phosphate network became more connected, whereas the addition of ZnO did not modify the optical, thermal and structural properties but it led to an enhanced fluorescence emission as compared to the other glasses.
Secondly, glass-ceramics (GCs) were processed by heat-treating the glasses to induce in-situ crystal growth. The effect of the crystallization on the properties of phosphate glasses containing Al2O3, TiO2 or ZnO was investigated. The structural, optical, and spectroscopic characterization allowed assessing the occurrence and properties of the Er3+-doped crystals in the glasses. Different crystal phases were obtained depending on the glass composition but Sr(PO3)2 was identified in all the glasses. Moreover, the surface crystallization of the GCs was increased along with the duration of the heat treatment. However, the site of the Er3+ ions was not strongly affected by the heat treatment except for the reference GC, where an increase of the luminescence properties was observed after the heat treatment probably due to the incorporation of Er3+ ions into the crystals.
Thirdly, particles-containing glasses were prepared using the direct doping method. A series of different Er3+-doped Al2O3, TiO2, ZnO and ZrO2 nano- and microparticles were synthesized using soft chemistry and then were added to phosphate-based glass batches prior to and after the melting. The survival and dispersion of the particles were optimized in order to increase the luminescence properties of the glasses. As evidenced by the morphological and compositional analyses, the Er3+ ions diffused from the particles to the glass matrix and no improvement of the spectroscopic properties was observed. A large amount of Er3+-doped particles were dissolved into the glasses probably due to the high temperatures achieved during the melting. As an alternative, glasses with different composition and lower melting temperatures were tested.
The last part of the project was the production and characterization of a multimode optical fiber made from phosphate-based glasses. The core composition was 0.25 Er2O3 – 97.25 (0.5 P2O5 – 0.4 SrO – 0.1 Na2O) – 2.5 ZnO, while the cladding composition was 98.25 (0.5 P2O5 – 0.4 SrO – 0.1 Na2O) – 1.75 ZnO. The cladding component was processed using the rotational casting technique, and the preform was successfully drawn into an optical fiber. This novel
optical fiber was found to be able to allow in-line monitoring of the fiber dissolution in H3PO4 and in simulated body fluid (SBF) solution. Bioactivity of the fiber was also assessed by the formation of a hydroxylapatite layer at the surface of the fiber after 4 weeks of immersion in SBF solution at room temperature.
In this thesis, a bioactive fiber sensor able to monitor its optical properties and in vitro reactivity was reported. This research activity demonstrates as a proof of principle the idea of tracking the bio-response of a bioactive optical fiber “in vivo”.
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Teixeira, Daniel. "Metodologia para a determinação das propriedades mecânicas de compósitos de poliamida 6.6 reforçados por fibras de vidro longas através da simulação de injeção." reponame:Repositório Institucional da UCS, 2017. https://repositorio.ucs.br/handle/11338/3388.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES
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Eberle, Aaron Paul Rust. "The Dynamic Behavior of a Concentrated Composite Fluid Containing Non-Brownian Glass Fibers in Rheometrical Flows." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28235.
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With this research, we work towards the overall objective of being able to accurately simulate fiber orientation in complex flow geometries of composite fluids of industrial significance. The focus of this work is to understand the rheological behavior of these materials and its connection to fiber orientation as determined in simple shear flow. The work includes the development of a novel approach to characterizing the transient rheology; an experimental study of the relationship between the stress growth functions in startup of flow and the fiber orientation; a critical assessment of the limitations of current fiber suspension theory; and an approach to determining unambiguous model parameters by fitting.
A key difference between the rheological studies performed in this work and others is the use of a cone-and-plate device combined with â donutâ shaped samples (CP-D) to prevent boundary effects on the measurement. The conventional method for obtaining transient rheological data is to use parallel disk (PP) geometry set at a gap where the measurements are independent of disk spacing. However, this work suggests that the inhomogeneous velocity gradient imposed by the PP geometry induces excessive fiber-fiber contact contributing to exaggerated measurements of the stress growth functions.
An experimental study of the transient rheological behavior of a 30 wt% short glass fiber-filled polybutylene terephthalate was performed using the CP-D. Stress growth measurements during startup of flow were performed in combination with direct measurement of the fiber orientation to determine the relationship between the transient rheology and the fiber microstructure. The well defined fiber orientation and rheological experiments allowed for a quantitative assessment of current fiber suspension theory. Comparison between the experimental fiber orientation and predictions based on Jefferyâ s equation and the Folgar-Tucker model show that the fiber orientation evolves much slower than predicted. In addition, the addition of a â slipâ term improved the agreement between the predictions and experimental results. Predictions using the Lipscomb model coupled with the Folgar-Tucker model, with slip, were fit to the transient stresses to determine the feasibility of fitting unambiguous model parameters for a specific composite fluid. Model parameters determined by fitting at a shear rate of 6 s-1 allowed for reasonable predictions of the transient stresses in flow reversal experiments at all the shear rates tested.Ph. D.
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Smulski, Stephen John. "Flexural behavior of a glass fiber reinforced wood fiber composite." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53596.
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The static and dynamic flexural properties of a wood fiber matrix internally reinforced with continuous glass fibers were investigated. When modelled as a sandwich composite, the static flexural modulus of elasticity (MOE) of glass fiber reinforced hardboard could be successfully predicted from the static flexural MOE of the wood fiber matrix, and the tensile MOE and effective volume fraction of the glass fiber reinforcement. Under the same assumption, the composite modulus of rupture (MOR) is a function of the reinforcement tensile MOE and effective volume fraction, and the matrix stress at failure. The composite MOR was predicted on this basis with limited success.
The static flexural modulus of elasticity, dynamic modulus of elasticity, and modulus of rupture of glass fiber reinforced hardboard increased with increasing effective reinforcement volume fraction. The logarithmic decrement of the composite decreased with increasing effective reinforcement volume fraction. Excellent linear correlation found among flexural properties determined in destructive static tests and nondestructive dynamic tests demonstrated the usefulness of dynamic test methods for flexural property evaluation.
The short-term flexural creep behavior of glass fiber reinforced hardboard was accurately described by a 4-element linear viscoelastic model. Excellent agreement existed between predicted and observed creep deflections based on nonlinear regression estimates of model parameters.Ph. D.
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Verlinden, Nicholas H. P. "The excited state absorption cross section of neodymium-doped silica glass fiber in the 1200-1500 nm wavelength range." Worcester, Mass. : Worcester Polytechnic Institute, 2008. http://www.wpi.edu/Pubs/ETD/Available/etd-072508-145557/.
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Sarmadi, Abdolmajid. "Effect of heat treatment on dyeability, glass transition temperature, and tensile properties of polyacrylonitrile fibers (orlon 42)." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49836.
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Deniers of treated and untreated fibers were determined and the „
results were used in calculations of tenacity and initial modulus.
Tensile properties were measured on a constant—rate—of—extension
machine. Shrinkage of treated and untreated fibers were measured
after they were boiled in water for 15 min. The glass transition
temperatures (Tg) were obtained by differential scanning calorimetry.
The ratio of the intensities of the CN/CH stretching bands were found
by infrared spectroscopy, using the KBr methodPh. D.
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Giraldi, Andre Luis Ferrari de Moura. "Compositos hibridos de poli (tereftalato de etileno) (PET) / fibra de vidro (FV) / modificador de impacto (E-MA-GMA)." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267212.
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Orientadores: Lucia Helena Innocentini Mei, Jose Alexandrino de SousaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Uma aplicação importante do poli (tereftalato de etileno) - PET - pós-consumo a ser considerada, e ainda pouco explorada, diz respeito ao seu reaproveitamento em outros setores diferentes, tais como o de compósitos híbridos de fibra de vidro (FV) com matriz polimérica e modificador de impacto, para aplicações diversas na área de engenharia. Deste modo, se fez necessário um estudo sistemático de compósitos de PET, reforçado com fibra de vidro e modificador de impacto para sua utilização numa aplicação de engenharia. E necessário que este apresente uma boa relação entre propriedades de rigidez e resistência ao impacto, e para isto dois sistemas de reforço foram propostos com dois tipos de fibra de vidro com diferentes tratamentos superficiais (FV 952 e 983). Ensaios de reometria de torque indicaram a reatividade entre os componentes PET e modificador de impacto. Os ensaios mecânicos demonstraram que o modulo elástico e a resistência a tração dos compósitos diminuem conforme se aumenta a concentração de E-MA-GMA em substituição ao PET na matriz. Entretanto, o modulo e a resistência ao impacto aumentaram da ordem de 300 % e 900% respectivamente para as concentrações de 30% de fibra de vidro (FV 952) e 20% de E-MA-GMA. O modulo de elasticidade e independente do tipo de tratamento superficial da fibra de vidro. A resistência a tração e a resistência ao impacto Izod dependem da natureza do tratamento de silano usado.
Abstract: An important application of poly(ethylene terephtalate) - PET - to be considered, and still not well explored, is its re-use in other different sectors, such as the obtaintion of PET composites reinforced with fibre glass (FG) and elastomer, for several applications in the engineering area. In this way, it is necessary a systematic study of several PET composites hybrids reinforced with fibre glass and impact elastomer to obtain a good balance between engineering properties such strength, rigidity ans impact resistance, two systems of reinforced were investigated using two types treatment of surface different (FG 952 and 983). Torque rheometry investigations during composite mixing indicated the reactivity between PET and elastomer. Mechanical tensile test on PET / fibre glass / elastomer composites hybrids indicated that the elastic modulus and tensile strength reduce monotonically as higher volume fractions of E-MA-GMA substitute PET in the composite matrix. Composites hybrids with 30 wt% of fibre glass (FG 952) and 20 wt% of elastomer indicates mechanical gains of the order of 300% in modulus e 900 % Izod impact. Tensile modulus is relatively independent of type of silane treatment applied to the glass fibers. Yield strength and Izod impact strength depend on the nature of silane treatment used.
Doutorado
Ciencia e Tecnologia de Materiais
Doutor em Engenharia Química
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Gao, Xiao. "Tailored interphase structure for improved strength and energy absorption of composites." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 5.63 Mb., 321 p, 2006. http://proquest.umi.com/pqdlink?did=1172119431&Fmt=7&clientId=79356&RQT=309&VName=PQD.
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Ehresman, Jonathan David. "Integration of actuators and sensors into composite structures." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/ehresman/EhresmanJ0809.pdf.
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The need for more efficient wind turbine blades is growing in our society. One step in accomplishing this task would be to make wind turbines blades into smart structures. A smart structure is one that incorporates sensors, complete control systems, and active control devices, in order to shed, or redistribute the load placed on the structure. For wind turbine blades this means changing the shape of the blade profile as it encounters different wind conditions. In order to have active control surfaces functioning on wind turbine blades, the existing blades would have to be retrofitted, and the new blades being manufactured would have to be redesigned. There are different control surfaces to consider: gurney flaps and false wall flaps are two that can perturb the boundary layer across the low pressure side of the wing. A flat plate and blade section test bed will be manufactured in order to gather empirical data from wind tunnel testing. For actuation of the control surface there are many choices: electrical, hydraulic, pneumatic, and electro-hydrostatic. These actuator types will be investigated under a set of criterion to determine the best one for turbine blade application. Sensors will be investigated with respect to their use in sensing strain, temperature, acceleration, humidity, and delamination. Sensors are also used for health monitoring. This helps engineers design under a damage tolerant philosophy as opposed to a safe life structure philosophy. These sensors will be placed into laminates and different surface treatments will be reviewed to find the best configuration for each sensor. The sensor will be cleaned with isopropyl alcohol, dipped in a 20% by mass solution of nitric acid, and submerged in a 20% by mass solution of nitric acid for 10 seconds. Detailed surface images will be taken of sensors with different surface treatments in order to better understand the bonding between the sensor and laminate. These images indicate that submerging the sensors into 20% by mass solution of nitric acid is the best surface treatment.
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Crate, Jon M. "Development of a test system to assess the effectiveness of adhesion promoters in glass and thermoplastic composites." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/20012.
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Plochý, Ondřej. "Vývoj sklobetonů s vysokými mechanickými vlastnostmi." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371943.
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This master thesis summarizes the current knowledge regarding the design and properties of glass fiber reinforced concrete products. It also deals with the design of a new concrete recipe for Dako spol. s.r.o company. There is verified effect of changes in input materials in real conditions the company to increase tensile bending strength above 20 MPa.In particular, verification of the use of building chemistry like superplasticizing additives, polymer-cement matrix or a change type or dose of glass fiber.
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Tzounis, Lazaros. "Glass and Jute fibers modified with CNT-based functional coatings for high performance composites." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-144493.
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Carbon nanotubes are known as one of the strongest materials in nature and since their discovery; they have triggered the scientific interest for fabricating multi-functional polymer composites. However, a well-known problem associated to the incorporation of nanoparticulate materials in polymer matrices is their tendency to agglomerate in order to reduce their surface energy, and the extreme increase of the polymer viscosities (i.e melts, solutions, etc), which makes it very difficult to process them. Polymers can be efficiently reinforced by fibers for applications where high strength and stiffness are required. Micro-scale short fiber reinforced polymer composites have been an alternative way to obtain fiber reinforced composites since the long fiber incorporation is a painful job and not always feasible and easy to produce composites in big scale.
Therefore, use of long glass fibers as the support for depositing CNTs as well as CNTs+other kind of nanoparticles was made, and the resulting interfaces were investigated in detail by single fiber model composites. This approach can bring the CNT functionality, fiber strength and toughness to the final composite, and simultaneously alleviate the manufacturing process from increase of the polymer high viscosities. Finally, very logically the question of whether to improve or destroy the interface integrity comes before implementing the hybrid hierarchical reinforcements in bigger scales, and an output out of this work will be given. Furthermore, several information and functionalities arising from the CNTs at the interphase region will be elucidated like cure monitoring of the epoxy resin matrix, UV-sensing ability, and thermoelectric energy harvesting, giving rise to multi-functional structural composites. CNT-modified natural fibers also have been utillised to fabricate short fiber reinforced composites, and have shown a promising reinforcement effect due to the CNT nanostructured interfaces.
The ‘interface’ in fiber reinforced polymer composites (FRPCs) is known as a very crucial parameter that has to be considered in the design of a composite with desired properties. Interfaces are often considered as surfaces however, they are in fact zones or areas with compositional, structural, and property gradients, typically varying from that of the fiber and the matrix material. Characterization of the mechanical properties of interfaces is necessary for understanding the mechanical behavior of scaled-up composites. In fact, the mechanical characteristics of a fiber/resin composite depend mainly on i) the mechanical properties of the component materials, ii) the surface of the fiber, and iii) the nature of the fiber/resin bonding as well as the mode of stress transfer at the interface. Among the many factors that govern the characteristics of composites involving a glass, carbon, natural or ceramic fiber, and a macromolecular matrix, the adhesion between fiber and matrix plays a predominant role. In specific, the stress transfer at the interface requires an efficient coupling between fiber and matrix. Therefore, it is important to optimize the interfacial bonding since a direct linkage between fiber and matrix gives rise to a rigid, low impact resistance composite material.
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Galleani, Gustavo. "Development of glass optical fibers based on fluoride-phosphate for deep-UV optical transmission /." Araraquara, 2017. http://hdl.handle.net/11449/152183.
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Orientador: Younes MessaddeqCoorientador: Silvia Helena Santagneli
Coorientador: Denis Boudreau
Banca: Marcelo Nalin
Banca: Hellmut Eckert
Banca: Martin Bernier
Abstract: The development of new optical fibers capable to operate in the deep-ultraviolet (DUV, 200-300 nm) and the vacuum-ultraviolet (VUV, 120-200 nm) would benefit to laser technologies, microlithography techniques (increased spatial resolution) and elemental chemical sensing applications (phosphorous and sulfur sensing in agriculture). The only well-established UV-transmitting fiber existing to date consists in high- OH/fluorine doped silica glass core/clad fibers. However, the utilization of such fibers is limited by solarisation effect that degrades the UV-light transmission with long time exposition. Mixed fluoride-phosphate (FP) glasses with ultra-low content of impurities can be VUV- and/or DUV-transmitting materials, offering thus an alternative to the commercialized high-OH/fluorine doped silica fibers. These glasses are produced by mixing fluorides and polyphosphates to combine their properties as excellent glass-forming ability, low refractive index and broad optical transmission windows ranging from ~160 to 4000 nm. Also, when doped with trivalent rare-earth (RE) ions, the low phonon fluorine environment is favorable for RE high quantum efficiencies, making then suitable for photonic application in the form of fiber and/or bulk glass. Firstly, highly pure FP glasses were prepared and utilized to fabricate step-index optical fibers, by a modified crucible technique. In a first step, the bulk glasses were studied to be highly transparent in the VUV region, down to 160 nm, ... (Complete abstract click electronic access below)
Resumo: O desenvolvimento de novas fibras ópticas capazes de operar na região do ultravioleta profundo (200-300 nm) e de vácuo (120-200 nm) beneficiariam aplicações em tecnologias a laser, técnicas de microlitografia (maior resolução espacial) e detecção química elementar (detecção de fósforo e enxofre na agricultura). A única fibra de transmissão UV bem estabelecida existente até o momento consiste em fibras núcleo-casca de vidro de sílica dopado com OH/flúor. No entanto, a utilização de tais fibras é limitada pelo efeito de solarização que degrada a transmissão da luz UV apos exposição prolongada. Os vidros mistos fluoreto-fosfato com baixas quantidades de impurezas, são materiais transmissores de luz UV-profundo e vácuo, oferecendo assim uma alternativa frente as fibras de silica utilizadas hoje. Estes vidros são produzidos pela mistura de fluoretos e polifosfatos com propriedades combinadas de ambos como, excelente capacidade de formação vítrea, baixo índice de refração e ampla janela de transmissão (~ 160 a 4000 nm). Além disso, quando dopados com íons terras-raras trivalentes, o ambiente de baixa energia de fonon dos fluoretos é favorável para emissões dos TRs com alta eficiência quântica, tornando-os então adequados para aplicações na área da fotônica na forma de fibra e/ou bulk. Portanto, em primeiro lugar, foram preparados vidros FP altamente puros e utilizados para fabricação de fibras ópticas de índice-degrau, pela técnica do cadinho. Na primeira etapa, os vidros na forma ... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor
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Galleani, Gustavo. "Development of glass optical fibers based on fluoride-phosphate for deep-UV optical transmission." Doctoral thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/28375.
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Thèse en cotutelle : Université Laval, Québec, Canada et Universidade Estadual Paulista “Júlio de Mesquita Filho” Araraquara, Brasil DoutoradoLe développement de nouvelles fibres optiques capables de transmettre dans les régions de l'ultraviolet moyen (200-300 nm) et lointain (120-200 nm) bénéficierait aux techniques de microlithographie, aux technologies laser, et également à la détection chimique (détection du phosphore et du soufre pour l'agriculture), ce qui représent la principale motivation de ce travail. En outre, les verres mixtes fluorure/phosphate peuvent offrir un environnement de fluorures de faible énergie de phonons qui est favorable pour l'émission avec une grande efficacité quantique lorsqu’ils sont dopés avec des ions de terre rare trivalents. Une telle propriété rend alors leur utilisation attractive pour d'autres applications également sous forme de fibres et/ou verres massifs dans le domaine de la photonique. La seule fibre connue pouvant opérer dans l’UV (~170-300 nm) est constituée de silice pure dopée avec OH/F. Cependant, l'utilisation de telles fibres est limitée par l'effet de solarisation qui dégrade la transmission de la lumière UV après une exposition prolongée. Les verres à base de fluorophosphate (FP) sont des matériaux hautement transparents dans l'UV lorsqu’ils possèdent de faibles quantités d'impuretés, offrant ainsi une alternative aux fibres de silice utilisées aujourd'hui dans cette région du spectre électromagnétique. Ces verres sont produits par le mélange de fluorures et polyphosphates et combinent ainsi leurs propriétés telles que: une excellente aptitude à vitrifier, un faible indice de réfraction et une large fenêtre de transmission (~ 160-4000 nm). Toutefois, peu d'études ont été rapportées à ce jour sur leur méthode de fabrication et par conséquent, les pertes optiques dans la région UV. En outre, lorsqu'il est dopé avec des ions de terres rares trivalentes (RE), l'environnement de faible énergie de phonon est favorable pour les efficacités quantiques élevées, ce qui permet une application photonique sous forme de fibre et/ou de verre massif. Par conséquent, des verres FP très purs ont été préparés et utilisés pour fabriquer des fibres optiques à saut d´indice, par une technique de creuset modifiée. Dans une première étape, les verres ont été étudiés pour être très transparents dans la région VUV, jusqu'à 160 nm, et les caractéristiques des températures, la viscosité autour du point de ramollissement ont été caractérisées. Ensuite, les fibres ont été fabriquées par la technique du creuset, par l´étirage d´une préforme à travers un creuset en silice fondue. Alors que la cristallisation incontrôlée a été observée lors du tirage des fibres par le procédé classique, l'étirage à partir d'un creuset en silice fondu s'est avéré approprié pour obtenir des fibres de verre FP exemptes de cristaux. Ensuite, des mesures d'atténuation ont été effectuées sur les fibres. La deuxième partie de cette thèse est compose de deux parties: l'étude structurale des verres FP avec différent ratios fluorure/phosphate et la corrélation des propriétés luminescentes des verres dopés avec des ions de terres rares avec leur structure. Les verres obtenus ont été caractérisés par différentes techniques, calorimétrie différentielle à balayage (DSC), spectroscopie Raman et résonance magnétique nucléaire à l’état solide (RMN). Au cours de l'étape suivante, on a utilisé des techniques de double resonance ²⁷Al/³¹P pour quantifier le nombre moyen de liaisons P-O-Al dans les verres et l'environnement local des espèces de fluorure a également été déterminé. Ensuite, les verres ont été dopées avec des ions de terres rares et l'environnement local a été caractérisé par spectroscopie de résonance paramagnétique électronique (RPE) de la sonde Yb³+ et par des expériences de photoluminescence sur des ions Eu³⁺. Les propriétés de la luminescence ont été corrélées avec la transformation structurale en fonction de la composition. Enfin, en raison de la haute transparence UV, nous avons préparé des verres FP dopées avec des ions Gd³+, Tm³+ et Yb³+ comme candidat potentiel pour la fabrication de lasers à fibre UV. Les propriétés de photoluminescence sous excitation au laser à diode de 980 nm ont été étudiées et l'effet des différent ratios fluorure/phosphate dans les verres sur l'émission de conversion ascendante UV du Gd³+ a egalement été etudié. Ensuite, leurs propriétés structurales ont également été explorées par la résonance magnétique nucléaire du ⁴⁵Sc, incorporé pour imiter les ions de terres rares dans la matrice vitreuse. En utilisant la technique de la double résonance ⁴⁵Sc/³¹P, la distribution du ligand entourant les ions de terres rares a été quantifiée et l'efficacité de l'émission du Gd³+ par rapport aux ions Tm³+ avec la structure a été effectuée.
The development of new optical fibers capable to operate in the deep-ultraviolet (DUV, 200-300 nm) and the vacuum-ultraviolet (VUV, 120-200 nm) would benefit to laser technologies, microlithography techniques (increased spatial resolution) and elemental chemical sensing applications (phosphorous and sulfur sensing in agriculture). The only well-established UV-transmitting fiber existing to date consists in high-OH/fluorine doped silica glass core/clad fibers. However, the utilization of such fibers is limited by solarisation effect that degrades the UV-light transmission with long time exposition. Mixed fluoride-phosphate (FP) glasses with ultra-low content of impurities can be VUV- and/or DUV-transmitting materials, offering thus an alternative to the commercialized high-OH/fluorine doped silica fibers. These glasses are produced by mixing fluorides and polyphosphates to combine their properties as excellent glass-forming ability, low refractive index and broad optical transmission windows ranging from ~160 to 4000 nm. Also, when doped with trivalent rare-earth (RE) ions, the low phonon fluorine environment is favorable for RE high quantum efficiencies, making then suitable for photonic application in the form of fiber and/or bulk glass. Firstly, highly pure FP glasses were prepared and utilized to fabricate step-index optical fibers, by a modified crucible technique. In a first step, the bulk glasses were studied to be highly transparent in the VUV region, down to 160 nm, and the characteristics temperatures, viscosity around softening point were characterized. Then, the fibers were fabricated by the crucible technique, drawing the as-made core-cladding preforms in a silica crucible assembly. While uncontrolled crystallization was observed during the fiber drawing by the conventional method, drawing from a fused silica crucible showed to be suitable to obtain crystal-free FP glass fibers. Additionally, the cut-back method was employed to measure the optical attenuation on the FP step-index and single index glass fibers. The second part of this thesis involves the network structural investigation of a series of FP glasses with different fluoride/phosphate ratio. Raman and multinuclear solid-state nuclear magnetic resonance (NMR) spectroscopies were used to study the polyphosphate network transformation for the different fluoride/phosphate ratios. In the next step ²⁷Al/³¹P double resonance techniques were used to quantify the average number of P-O-Al linkages in the glasses and the local environment of fluoride species were also determined. Then, the glasses were doped with RE ions and the local environment was characterized by electron paramagnetic resonance (EPR) spectroscopy of Yb³+ ions probe and by photoluminescence experiments on Eu³+ dopant ions. The luminescence properties were correlated with the structural transformation as a function of composition. Lastly, due to the high UV tansparency of the FP glasses, we prepared FP glasses doped with Gd³+, Tm³+, and Yb³+ ions as a potential candidate for fabrication of UV fiber lasers. The photoluminescence properties under 980 nm diode laser excitation were studied, and the effect of fluoride/phosphate ratio in the glasses in the Gd³+ UV upconversion (UC) emission were verified. The effect of Gd³+ content in the UV UC emission was also studied. Then, by using ⁴⁵Sc/³¹P double resonance technique, utilizing scandium as a diamagnetic mimic for the luminescent RE species, the ligand distribution surrounding the RE ions were quantified, and the efficiency of the Gd³+ emission, compared to the Tm³+ ions with structure was done.
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Fan, Zhihang. "Flow and rheology of multi-walled carbon nanotubes thermoset resin suspensions in processing of glass fiber composites." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 254 p, 2007. http://proquest.umi.com/pqdweb?did=1362534231&sid=8&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Elhage, Ayda. "Palladium-based Catalyst for Heterogeneous Photocatalysis." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39388.
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Over the past decade, heterogeneous photocatalysis have gained lots of interest and attention among the organic chemistry community due to its applicability as an alternative to its homogeneous counterpart. Heterogeneous catalysis offers the advantages of easy separation and reusability of the catalyst. Several studies showed that under optimized conditions, efficient and highly selective catalytic systems could be developed using supported metal/metal oxide nanoparticles. In this dissertation, we summarize the progress in the development of supported palladium nanoparticles for different types of organic reactions.
Palladium-decorated TiO2 is a moisture, air-tolerant, and versatile catalyst. The direct excitation of Pd nanoparticles selectively isomerized the benzyl-substituted alkenes to phenyl-substituted alkenes (E-isomer) with complete conversion over Pd@TiO2 under H2-free conditions. Likewise, light excited Pd nanoparticles catalyzed Sonogashira coupling, a C-C coupling reaction between different aryl iodides and acetylenes under very mild conditions in short reaction times. On the other hand, UV irradiation of Pd@TiO2 in alcoholic solutions promotes alkenes hydrogenation at room temperature under Argon. Thus, The photocatalytic activity of Pd@TiO2 can be easily tuned by changing the irradiation wavelength. Nevertheless, some of these systems suffer from catalyst deactivation, one of the main challenges faced in heterogeneous catalysis that decreases the reusability potential of the materials. In order to overcome this problem, we developed an innovative method called “Catalytic Farming”. Our reactivation strategy is based on the crop rotation system used in agriculture. Thus, alternating different catalytic reactions using the same catalyst can reactivate the catalyst surface by restoring its oxidation states and extend the catalyst lifetime along with its selectivity and efficiency. In this work, the rotation strategy is illustrated by Sonogashira coupling –problem reaction that depletes the catalyst– and Ullmann homocoupling –plausible recovery reaction that restores the oxidation state of the catalyst (Pd@TiO2). The selection of the reactions in this approach is based on mechanistic studies that include the role of the solvent and evaluation of the palladium oxidation state after each reaction.
In a more exploratory analysis, we successfully demonstrated that Pd nanoparticles could be supported in a wide range of materials, including inert ones such as nanodiamonds or glass fibers. The study of the action spectrum shows that direct excitation of the Pd nanoparticles is a requisite for Sonogashira coupling reactions. The main advantages of heterogeneous catalysis compared to its homogeneous counterpart are easy separation and reusability of the catalyst.
Finally in order to facilitate catalyst separation from batch reaction and develop a suitable catalytic system for continuous flow chemistry, we employed glass fibers as catalyst support for a wide variety of thermal and photochemical organic reactions including C-C coupling, dehalogenation and cycloaddition. Different metal/metal oxide nanoparticles, namely Pd, Co, Cu, Au, and Ru were deposited on glass wool and fully characterized. As a proof of concept, Pd decorated glass fibers were employed in heterogeneous flow photocatalysis for Sonogashira coupling and reductive de-halogenation of aryl iodides.
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Hatcher, Brian Matthew. "Polyvinylpyrrolidone modified bioactive glass fibers as tissue constructs: synthesis, characterization, and rat mesenchymal stem cell response." [Gainesville, Fla.] : University of Florida, 2002. http://purl.fcla.edu/fcla/etd/UFE0000543.
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Chazot, Matthieu. "Spectroscopie multimodale et optimisation de multimatériaux." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0259/document.
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Les composés multimatériaux à base de verre connaissent aujourd’hui un intérêt croissant, en particulier sous la forme de fibres optique pour des applications dans l’infrarouge. Parmi les matériaux vitreux qui existent, les verres chalcogénures présentent de nombreux avantages, tel qu’un large domaine de transparence allant du visible à l’infrarougeou encore de bonne aptitude à pouvoir être étirer. Pour réaliser de nouvelles fibres multimatériaux, il est important d’avoir accès à un choix étendu de compositions vitreuses étirables pouvant servir de matrice hôte. Il peut être montré que les verres actuellement utilisés pour la réalisation de fibres multimatériaux couvrent deux plages de température de transition vitreuse différentes ; soit à basse température (100-250 °C), ou à haute température (1000 °C et plus). Le manque d’information sur des verres étirables couvrant un domaine intermédiaire de température entre 250 et 1000 °C, nous ont conduit à explorer les propriétés et les capacités d’étirement des verres des deux systèmes ternaires Ge-S-I et Ga-As-S. Il sera montré que ces systèmes vitreux ont en effet des Tg permettant de couvrir cette gamme intermédiaire de température et ont de larges domaines de formation vitreux. Un ensemble de caractérisations physiques et thermiques sur les verres au sein des systèmes ternaires Ge-S-I et Ge-As-S seront présentés et analysés. Il sera possible d’observer, comment notamment les résultats des mesures thermomécaniques et de viscosité des échantillons synthétisés ont permis d’aborder dans les meilleures conditions les tests d’étirement des verres. Ou encore comment l’analyse minutieuse des propriétés a pu permettre de définir un domaine de composition combinant à la fois des propriétés optimales en termes de Tg et de transparence dans le visible, avec une bonne capacité à pouvoir être étirées sous forme de fibres optiques. Pour la première fois les domaines de fibrage des deux ternaires à partir de l’étirement d’une préforme seront présentés dans ce manuscrit. Ce travail présente également une caractérisation structurale des verres Ge-S-I. Cette étude a été réalisé en combinant la spectroscopie Raman, la spectroscopie IR et des calculs de chimie théorique afin de proposer un nouveau modèle structural basé sur les avancés les plus récentes d'une part sur la structure du système binaire Ge-S, puis ternaire Ge-S-I.Enfin, les résultats préliminaires sur la réalisation de fibres multimatériaux à partir de verres Ge-S-I et Ge-As-S pour la réalisation de sources laser entre 3 et 5 µm, seront présentés. Le projet, la méthodologie et les résultats quant à la réalisation d’une fibre multimatériaux à base de verre chalcogénure avec un cœur cristallisé de ZnS à partir de deux techniques innovantes différentes, seront présentésNowadays, the interest on multimaterials based on glass matrix growth constantly, in particular in the field of multimaterial optical fibers for IR applications. Among the glass materials that exist, chalcogenide glasses presents a lot of advantages as for instance large transparency windows, spanning from the visible to the infrared or also good capability to be drawn. In the aim to realize new multimaterials fibers, it is important to get a large choice of draw able glass compositions that can be used as host matrix. It can be shown that the glass used currently to make multimaterial fibers covers two glass transition temperature range ; low temperature (100-250 °C) and high temperature (1000 °C and more). The lack of information regarding the existence of glass compositions that can be drawn into fibers at intermediate temperature (between 250 and 1000 °C), has lead us to explore the properties and the draw ability of glasses into two ternary systems: Ge-As-S and Ge-S-I. It will be presented that these glass systems possess Tg that covers this intermediate range of temperature and have large glass forming regions. Some physical and thermal characterizations of Ge-As-S and Ge-S-I glasses will be presented and analyzed. It will be possible to observe how the thermomechanical and viscosity measurements made on the different samples enabled us to perform the drawing tests in the best conditions. It will be also possible to see how a careful analysis of the Ge-S-I glass properties gave us the possibility to define a glass region combining optimal properties as Tg and transparency in the visible, and good capability to be drawn. For the first time, the fiber drawing region of both systems will be presented in this thesis. This work present also a structural characterization of Ge-S-I glasses using IR and Raman spectroscopy as well as DFT calculations, in the aim to propose a new structural model based on recent development in the Ge-S network structure. Finally, preliminary results on the realization of Ge-S-I and Ge-As-S based multimaterial fibers for the production of IR laser sources between 3 and 5 µm, will be presented. The last chapter will present the project, the methodology and the results obtained to realize multimaterial fibers with ZnS core, using two different technics
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Kalyankar, Rahul R. "Natural fiber reinforced structural insulated panels for panelized construction." Birmingham, Ala. : University of Alabama at Birmingham, 2009. https://www.mhsl.uab.edu/dt/2010r/kalyankar.pdf.
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MacHuca, Joao Rodriguez, Quispe Oscar Pusari, Gary Duran Ramirez, and Diaz Carlos Fernandez. "Improvement of the shear strength parameters of an expansive soil using recycled glass powder and polypropylene fibers." Institute of Electrical and Electronics Engineers Inc, 2020. http://hdl.handle.net/10757/656416.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.n this article, the geotechnical behavior of the reinforced soil is studied through additions of polypropylene fiber and recycled glass powder, this in order to obtain a homogeneously reinforced soil matrix to reduce possible structural failures, differential settlements and increase capacity bearing. The sample used was classified as a clay soil with low plasticity (CL) and with moderately expansive characteristics, based on the values of the Liquid Limit, Plastic Limit and Plasticity Index. The effect of the 1% polypropylene fiber and different amounts of recycled glass powder (0%, 4%, 5%, 6.5%), with respect to dry weight is analyzed in this soil. The purpose of varying the quantity of these materials is to find a trend of the strength parameters and obtain the optimal percentages that provides improvements in geotechnical behavior. Modified Proctor and Direct Shear tests were carried out, this latter to obtain the shear strength parameters of the mixtures and compare them with the clay soil. Finally, the optimal result for soil improvement was the mixture made by 1% polypropylene fiber and 4% glass powder, which achieved an increase of the angle of friction and cohesion.
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Meyer-Scherf, Ronald [Verfasser], and Thomas [Akademischer Betreuer] Böllinghaus. "The pressure resistance of hollow glass fibers at internal pressure load / Ronald Meyer-Scherf. Betreuer: Thomas Böllinghaus." Magdeburg : Universitätsbibliothek, 2015. http://d-nb.info/1082625795/34.
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Alam, Sameer Alam. "Plastic and Slag as a Potential Aggregate Replacement in Concrete with Glass Fibers and Silica Fume Admixtures." Youngstown State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1544787269399169.
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Montes, Thisien Gabriel 1988. "Caracterização experimental de fibras de vidro telurito dopado com érbio e itérbio : Experimental characterization of tellurite glass fibers doped with erbium and ytterbium." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261920.
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Orientador: Aldário Chrestani BordonalliDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
Made available in DSpace on 2018-08-27T14:08:20Z (GMT). No. of bitstreams: 1 Montes_ThisienGabriel_M.pdf: 6660294 bytes, checksum: 3ca5cc8372729ad8e25455441ebddef9 (MD5) Previous issue date: 2015
Resumo: Com a demanda por comunicação continuamente aumentando nos últimos anos, mantém-se constante a busca por aperfeiçoamento dos amplificadores ópticos a fibra. Como uma proposta de proporcionar maior largura de banda de amplificação para sistemas ópticos, este trabalho procura caracterizar o comportamento operacional de uma fibra de vidro telurito dopado com érbio e itérbio para diferentes condições iniciais de comprimento de amostra, aplicação de sinais e configuração de bombeio. As amostras, fabricadas pelo Grupo de Fibras Ópticas do IFGW/UNICAMP, foram submetidas a análises experimentais baseadas nas principais topologias de amplificadores a fibra que usam matrizes de sílica. Assim, avalia-se a potencialidade das características de amplificação do vidro telurito fabricado com dosagem de compostos inéditos, além de uma investigação da possibilidade da geração laser utilizando-se essa fibra como meio ativo em configurações com laço de realimentação. Mesmo que o ganho real do sistema não tenha sido determinado pela incerteza em relação a real potência óptica acoplada às amostras, observou-se ser possível a compensação da atenuação que o sinal que se propaga pelas amostras sofre após a aplicação de bombeio. Nesse aspecto, o vidro telurito dopado com érbio e itérbio apresentou potencial de aplicação em amplificação óptica. Uma amostra de 2 cm, comprimento muito menor que o usado em amplificadores ópticos baseados em matrizes de sílica e uma ordem de grandeza menor que os baseados em vidro telurito dopado apenas com érbio, apresentou resultados de ganho óptico on-off da ordem de 30 dB com bombeio bi-direcional de 100 mW. Em relação ao vidro telurito dopado apenas com érbio, os resultados para o ganho on-off chegaram a ser até 15 dB maiores. Além disso, as transições providas pela interação entre a matriz vítrea com o érbio e o itérbio levaram a larguras de banda de 3 dB para o espectro de ASE de até 70 nm, dependendo da configuração de bombeio
Abstract: With the recently increase in data transmission demands, the search for improved fiber amplifier physical processes, materials, and configurations is still on going. As a way to provide a wider amplification bandwidth for optical systems, this work intends to characterize the operational behavior of an erbium and ytterbium doped tellurite fiber for different sample lengths, light coupling and pump configurations. The fiber samples, manufactured by the Optical Fiber Group of the IFGW/UNICAMP, underwent experimental analyses based on the same main pump topologies as those of silica-based optical amplifiers. Thus, the potential amplification characteristics of tellurite glass doped with new compounds are evaluated, as well as an investigation of possible laser generation by using this type of fiber as gain medium within feedback loop configurations. Although real system gain was impossible to determine due to uncertainties in the actual coupled optical power, it was observed that the attenuation during signal propagation through the fiber samples could be compensated after pump application. In this context, the erbium and ytterbium doped tellurite fiber has potential for optical amplification. Samples as short as 2 cm, far shorter than the ones used in silica based amplifiers and one order of magnitude shorter than those based on Er3+ doped tellurite fiber structures, presented on-off optical gain of the order of 30 dB for bi-directional 100-mW pump. By comparing with the latter doped glass structure, the on-off gain results were as high as 15 dB greater. Furthermore, the transitions provided by the interaction between the host glass and both erbium and ytterbium have led to a 70-nm ASE bandwidth, depending on the pumping configuration
Mestrado
Telecomunicações e Telemática
Mestre em Engenharia Elétrica
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Caratin, Reinaldo Leonel. "Desenvolvimento de compósitos de matriz cimentícia com reforços contínuos de fibras de carbono e fibras de vidro." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-22012015-163331/.
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Resíduos da área de engenharia civil decorrentes da recuperação de estruturas danificadas por agentes agressivos contribuem continuadamente para impactar o meio ambiente de maneira cada vez mais preocupante. O desenvolvimento de novas tecnologias que sejam aceitáveis do ponto de vista ambiental e financeiro provou ser um grande desafio na solução desse problema quando se compara o custo original e eficaz em médio e longo prazo ao custo da demolição, destinação desse material e reconstrução da obra. Para viabilizar a utilização de compósitos de fibras sintéticas como reforço resistente a ambientes agressivos em elementos de concreto, os aparatos de ensaio e os corpos de prova foram modificados e adaptados aos sistemas operacionais descritos pelas normas técnicas vigentes, a partir da concepção do uso de filamentos de fibra contínua. Dado o caráter inovador do trabalho, não se identificou uma norma que tratasse especificamente dos ensaios de flexão nem pullout com fibras contínuas em blocos de concreto. Portanto, para se conseguir um aproveitamento desse tipo de reforço que respondesse satisfatoriamente quando comparado às armaduras metálicas, foi aplicada uma rugosidade à superfície da haste para garantir sua aderência ao bloco de concreto. Pelo método de preparo de compósitos de matriz cimentícia proposto no presente estudo, foram determinados os valores da força de arrancamento dos reforços com fibras de carbono e vidro-AR, os quais, no caso das fibras de carbono, apresentaram aumentos significativos entre 76% e 158% e 47% e 120% respectivamente para concretos de resistência à compressão de 30 MPa (fcm 30) e 40 MPa (fcm 40) comparados com valores obtidos para barras de aço.In Civil Engineering, the waste from the recovery of structures that were damaged by aggressive agents continuously contribute to impact the environment in an increasingly concerning way. The development of new technologies that would be environmentally and financially acceptable has become a major challenge to solve that problem when one compares the medium and long term original and effective cost to the cost of demolition, destination of that material and rebuilding. To enable the use of synthetic fiber composites as a resistant reinforcement to aggressive environments in concrete elements, the test apparatus and the specimens were changed and suited to the operational systems described by current technical standards from the conception of the use of continuous fiber filaments. Given the innovative character of the present work, no standard specifically related to bending and pullout tests with continuous fibers in concrete blocks has been identified. Therefore, in order to obtain good use of that kind of reinforcement that would respond satisfactorily when compared to metallic bars, some rugosity was applied to the rod surface in order to ensure its adherence to the concrete block. The preparation method of cement matrix composites proposed in the present work has determined pullout strength values and reinforcement with carbon and AR glass fiber values, which, regarding carbon fibers, showed significant increase between 76% and 158% and 47% and 120% respectively for compression resistant concrete of 30 MPa (fcm 30) and 40 MPa (fcm 40) compared to the obtained values for steel bars.
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Lozano, Flavien. "Elaboration de matelas à base de fibres de verre par voie humide." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI001.
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Les matelas fibreux à base de fibres de verre produits par voie humide ont des applications industrielles en tant que séparateur de batterie et matériaux d’isolation (cœur de panneaux d’isolation sous vide). Ces matériaux utilisent principalement des fibres submicroniques, relativement chères et pouvant présenter des risques pour la santé. Ce projet est une contribution à l'élaboration d'un procédé de fabrication par voie humide de matelas de fibres de verre visant à valoriser des fibres plus grossières, le produit final devant respecter un cahier des charges précis. Nous avons été amenés à étudier le comportement des fibres de verre dans les différentes étapes du procédé et à caractériser les matelas résultants. Nous nous sommes intéressés en particulier au comportement physico-chimique des suspensions aqueuses de fibres de verre. Nous avons caractérisé les propriétés de contexture, la résistance mécanique en traction, la compressibilité et la conductivité thermique des matelas fibreux. Les travaux expérimentaux nous ont permis de proposer une formulation de la composition optimisée et des conditions opératoires du procédé afin que le matelas final soit conforme au cahier des charges. Cette nouvelle composition intègre des fibres de renfort en faible quantité. Elle permet d’améliorer les caractéristiques mécaniques sans affecter les autres propriétés.Enfin, nous avons quantifié les coûts de production et les avons comparés à ceux du procédé actuellement utilisé avec des fibres grossières (production par voie sèche).Mots-clés : Génie papetier, physico-chimie, milieu poreux, fibres de verre, caractérisationGlass fibre - based mats produced by a wetlaid process have industrial applications as a battery separator and insulation materials (core of vacuum insulation panels). These materials are mainly made with sub-micron fibres which relatively expensive and can present a risk to health. This project is a contribution to the production of glass fibre-based mats by a wet-laid process to add value to coarser fibres, the final product should respect precise specifications. We have been led to study the behavior of glass fibers in different stages of the process and to characterize the resulting mats. We investigated especially the physico-chemical behavior of aqueous suspensions of glass fiber. We have characterized structure properties, the mechanical resistance to traction, the compressibility and the thermal conductivity of fibrous mats. The experimental work has allowed us to give a formulation of the optimized composition and operational conditions of the process so that the final mattress conforms to the specifications. This new composition includes reinforcement fibres in small quantities. It allows improving the mechanical characteristics without affecting the other properties. Finally, we quantified the production costs and compared them to those of the process currently used with coarse fiber (dry-laid production).Keywords: Paper engineering, physical chemistry, porous media, glass fibre, characterization
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Bonnell, Elizabeth Ann. "Temperature Dependent Behavior of Optical Loss from Hydrogen Species in Optical Fibers at High Temperature." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/78132.
Full textAbstract:
This study reports on the behavior of silica based optical fibers in a hydrogen environment at high temperatures. The hydrogen response in the form of optical loss in the wavelength range of 1000-2500 nm of a germanium doped graded index 50/125 graded index fiber was examined in the temperature range of 20–800 °C. When the fiber was exposed to hydrogen at 800 °C two absorption bands appeared: ~1390 nm assigned to the first overtone of the hydroxyl stretch and ~2200 nm band with complex assignments including the combination mode of the fundamental hydroxyl stretch with SiO4 tetrahedral vibrations and the combination mode of SiOH bend and stretch. The growth rate of the 1390 nm band fits the solution to the diffusion equation in cylindrical coordinates while the 2200 nm band does not. Absorption for both bands persisted as the fiber is cooled to room temperature. Temperature dependent behavior was observed in that as temperature increases from room temperature, the absorption intensity decreases and band shifts slightly to longer wavelengths. Temperature dependence is repeatable and reversible. However, if no hydrogen is present in the environment at temperatures greater than 700 °C, the 1390 nm band will permanently decrease in intensity, while the 2200 nm band does not change. Changes in the structure of the glass appear to be causing this temperature dependent behavior. Other necessary conditions for structural changes to cause this temperature dependent behavior are examined.Master of Science