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1
Jha, Vineetkumar. « Carbon black filler reinforcement of elastomers ». Thesis, Queen Mary, University of London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510795.
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Ogden, Gary N. « The quality of binder-filler interfaces in carbon electrodes ». Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/7049.
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The aims of this research project were to identify and classify the binder-filler interfaces formed in carbon electrodes and to determine the effects of the interfacial quality on important electrode properties. The effects of raw materials and some fabrication process variables on interfacial characteristics and quality of laboratory produced test electrodes were also studied, and the development of binder-filler interfaces during the carbonisation process followed. Electrode quality was assessed by measurement of density, electrical resistivity and tensile strength. Pore structural data were also obtained by using a computerised image analysis system allied to an optical microscope. Interface quality data were obtained by examining etched surfaces in a scanning electron microscope and classifying the binder-filler interface observed into one of five categories. The category depending on the extent of contact between the binder and filler. Accordingly, test electrodes were produced from combinations of four filler carbons, comprising three grades of calcined petroleum coke and an electro-calcined anthracite, and four coal-tar binder pitches which varied in the type and quantity of insoluble matter content. Examination of these test electrodes showed that the nature of the filler carbon used had a dominant influence on the quality of the interface formed, as assessed by this technique. A combination of one filler carbon and one binder pitch was used to study the effects of some fabrication process variables. These were pitch content and, mixing time and temperature. Of these process variables, pitch content and mixing temperature were found to have the major effects on the binder-filler interface and electrode quality. Investigation of the development of the binder-filler interfaces during the carbonisation process showed three distinct zones of interface development and transformation. These zones were associated with three temperature dependent mechanisms; thermal stress relaxation between 200-350 degrees C, volatile gas evolution from coal-tar pitch decompositionb etween3 50-600 degrees C and stresses induced by thermal contraction of the binder phase between 600-1000 degrees C.
3
LI, Jr-Hung. « INFRARED BRAZING OF LOW CARBON SPEED WITH COPPER FILLER ». University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin990736063.
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Xu, Huagen [Verfasser], Dirk [Akademischer Betreuer] Schubert et Dirk [Gutachter] Schubert. « Electrical Conductivity of Binary PMMA/carbon-based filler and Ternary Poly(alkyl methacrylate)/PS/carbon-based filler composite films / Huagen Xu ; Gutachter : Dirk Schubert ; Betreuer : Dirk Schubert ». Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2020. http://d-nb.info/1222267993/34.
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Nitschke, Annika. « Investigation of Polymer-Filler Interactions Using Functionalized Nanoparticles ». Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-1363-6.
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Albehaijan, Hamad A. « Approaches to Enhance Filler-Polymer Interactions and Cure Properties of Rubber Compounds ». University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1491515276428703.
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Sun, Weicheng. « Use of Torrefied Sorghum as Eco-friendly Filler in Styrene Butadiene Rubber ». University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1527786418607651.
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Prystaj, Laurissa Alia. « Effect of carbon filler characteristics on the electrical properties of conductive polymer composites possessing segregated network microstructures ». Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/31667.
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Thesis (M. S.)--Materials Science and Engineering, Georgia Institute of Technology, 2009.Committee Chair: Rosario Gerhardt; Committee Member: Gleb Yushin; Committee Member: Hamid Garmestani. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Ren, Xianjie ren. « Use Of Fly Ash As Eco-Friendly Filler In Synthetic Rubber For Tire Applications ». University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1463148731.
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Bryan, Nicholas James. « PEBAX-based mixed matrix membranes for post-combustion carbon capture ». Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31239.
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Polymeric membranes exhibit a trade-off between permeability and selectivity in gas separations which limits their viability as an economically feasible post-combustion carbon capture technology. One approach to improve the separation properties of polymeric membranes is the inclusion of particulate materials into the polymer matrix to create what are known as mixed matrix membranes (MMMs). By combining the polymer and particulate phases, beneficial properties of both can be seen in the resulting composite material. One of the most notable challenges in producing mixed matrix membranes is in the formation of performance-hindering defects at the polymer-filler interface. Non-selective voids or polymer chain rigidification are but two non-desirable effects which can be observed. The material selection and synthesis route are key to minimising these defects. Thin membranes are also highly desirable to achieve greater gas fluxes and improved economical separation processes. Hence smaller nano-sized particles are of particular interest to minimise the disruption to the polymer matrix. This is a challenge due to the tendency of some small particles to form agglomerations. This work involved introducing novel nanoscale filler particles into PEBAX MH1657, a commercially available block-copolymer consisting of poly(ethylene oxide) and nylon 6 chains. Poly(ether-b-amide) materials possess an inherently high selectivity for the CO2/N2 separation due to polar groups in the PEO chain but suffer from low permeabilities. Mixed matrix membranes were fabricated with PEBAX MH1657 primarily using two filler particles, nanoscale ZIF-8 and novel nanoscale MCM-41 hollow spheres. This work primarily investigated the effects of the filler loading on both the morphology and gas transport properties of the composite materials. The internal structure of the membranes was examined using scanning electron microscopy (SEM), and the gas transport properties determined using a bespoke time-lag gas permeation apparatus. ZIF-8 is a zeolitic imidazolate framework which possesses small pore windows that may favour CO2 transport over that of N2. ZIF-8-PEBAX membranes were successfully synthesised up to 7wt.%. It was found that for filler loadings below 5wt.%, the ZIF-8 was well dispersed within the polymer phase. At these loadings modest increases in the CO2 permeability coeffcient of 0-20% compared to neat PEBAX were observed. Above this 5wt.% loading large increases in both CO2, N2 and He permeability coeffcients coincided with the presence of large micron size clusters formed of hundreds of filler ZIF-8 particles. The increases in permeability were attributed to voids observed within the clusters. MCM-41 is a metal organic framework that has seen notable interest in the field of carbon capture, due to its tunable pore size and ease of functionalisation. Two types of novel MCM-41 hollow sphere (MCM-41-HS) of varying pore size were incorporated into PEBAX and successfully used to fabricate MMMs up to 10wt.%. SEM showed the MCM-41 generally interacted well with the polymer with no signs of voids and was generally well dispersed. However, some samples of intermediate loading in both cases showed highly asymmetric distribution of nanoparticles and high particle density regions near one external face of the membrane which also showed the highest CO2 permeability coeffcients. It is suspected that these high permeabilities are due to the close proximity of nanoparticles permitting these regions to act in a similar way to percolating networks. It was determined that there was no observable effect of the varying pore size which was expected given the transport in the pores should be governed by Knudsen diffusion.
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Agovino, Anna. « Metathesis reactions catalyzed by ruthenium complexes for the self-healing of aeronautical materials ». Doctoral thesis, Universita degli studi di Salerno, 2018. http://hdl.handle.net/10556/3171.
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2015 - 2016In this PhD thesis work, Ruthenium catalysts were covalently and non-covalently linked to carbon-based nanomaterials, in order to give self-repairing ability to the aeronautical materials. These supported catalysts have been characterized and their activity has been evaluated in metathesis reactions. The 1st and 2nd generation Grubbs and Hoveyda-Grubbs catalysts were covalently bonded to graphite oxide and tested in the ring-opening metathesis polymerization reaction of tensed monomers, and subsequently their catalytic activity was verified in the aeronautical composites. To optimize the performance of such supported catalysts, catalytic sites have been protected from the highly reactive environment by a polymeric globular shell. These catalysts have been further supported on multi-walled carbon nanotubes and graphite by an alternative covalent synthetic approach that allows to preserve the chemical and physical properties of the carbon nanotubes employed, avoiding the initial oxidation step. For non-covalent functionalization, the same catalysts were first linked to pyrene molecules and then, by π-stacking, anchored on graphite. Their activity was determined in metathesis reactions and their conductivity was estimated within aeronautical composites. Such complex pyrene-catalyst, highly versatile, have been used to synthesize polymers having a terminal pyrene capable of improving the dispersion of the same carbon nanotubes used in aeronautical materials in order to improve their performance. Lastly, was evaluated the possibility of self-repairing the aeronautical material through radical polymerization of monomers such as styrene, using Copper catalysts.[edited by author]
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Kuper, Michael W. « Investigations Near the Fusion Boundary of Grade 91 Steel Dissimilar Metal Welds with Nickel Based Filler Metals ». The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1543505600533312.
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Al-Shenawa, Amaal Abdallah Ali. « Effectiveness of Fillers for Corrosion Protection of AISI-SAE 1018 Steel in Sea Salt Solution ». Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984141/.
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Corrosion represents the single most frequent cause for product replacement or loss of product functionality with a 5% coat to the industrial revenue generation of any country in this dissertation the efficacy of using filled coatings as a protection coating are investigated. Fillers disrupt the polymer-substrate coating interfacial area and lead to poor adhesion. Conflicting benefits of increasing surface hardness and corrosion with long term durability through loss of adhesion to the substrate are investigated. The effects of filler type, filler concentration and exposure to harsh environments such as supercritical carbon dioxide on salt water corrosion are systematically investigated. The constants maintained in the design of experiments were the substrate, AISI-SAE 1018 steel substrate, and the corrosive fluid synthetic sea salt solution (4.2 wt%) and the polymer, Bismaleimide (BMI). Adhesion strength through pull-off, lap shear and shear peel tests were determined. Corrosion using Tafel plots and electrochemical impedance spectroscopy was conducted. Vickers hardness was used to determine mechanical strength of the coatings. SEM and optical microscopy were used to examine dispersion and coating integrity. A comparison of fillers such as alumina, silica, hexagonal boron nitride, and organophilic montmorillonite clay (OMMT) at different concentrations revealed OMMT to be most effective with the least decrease in adhesion from filler-substrate contact. Subsequently examining filler concentration, a 3 wt% OMMT was found to be most effective. A comparison of unmodified and modified BMI with 3 wt% OMMT exposed and not exposed to supercritical carbon dioxide showed that the BMI provided better corrosion protection; however, OMMT provided better wear, shear, and hardness performance.
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Tricàs, Rosell Núria. « Plasma modification on carbon black surface : From reactor design to final applications ». Doctoral thesis, Universitat Ramon Llull, 2007. http://hdl.handle.net/10803/9288.
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El present treball es basa en l'estudi de la modificació de la superfície del negre de carboni (NC) per mitjà de tècniques de plasma. Tot i que aquest tipus de tractament s'utilitza de manera comú sobre superfícies planes, tanmateix encara existeixen problemes a l'hora de treballar en materials en pols degut a la dificultat que suposa la seva manipulació. En aquest treball s'ha modificat NC tant per tècniques de plasma a baixa pressió com per mitjà de tècniques de plasma atmosfèric. Per tal d'assolir aquest objectiu s'han posat a punt tres reactors de plasma capaços de modificar aquest tipus de material; dos reactors treballen a baixa pressió mentre que el tercer es tracta d'un equip a pressió atmosfèrica.Els sistemes de plasma a baixa pressió utilitzats han estat un reactor down-stream i un reactor de llit fluiditzat. Ambdós sistemes utilitzen un generador de radio freqüències a 13,56MHz per tal de general el plasma. Tots dos sistemes han estat optimitzats per la modificació de materials en pols. En el cas del reactor down-stream, s'ha estudiat a posició d'entrada del gas reactiu, la potència del generador i el temps de modificació per a tres tipus de tractament: oxigen, nitrogen i amoníac. En el cas del reactor de llit fluiditzat, els paràmetres que s'han estudiat han estat la distància entre la pols i la zona de generació de plasma, la mida de la partícula i la porositat de la placa suport.
Pel que fa a la modificació mitjançant la utilització de plasma atmosfèric, s'ha dissenyat un sistema que permet utilitzar una torxa de plasma atmosfèric comercial (Openair® de Plasmatreat GmbH) per tal de modificar materials en pols. Aquest sistema consisteix en un reactor adaptable a la torxa de plasma atmosfèric on té lloc la modificació, un sistema d'introducció de la pols dins de la zona de reacció així com també un sistema de refredament i col·lecció del material modificat que conjuntament permeten un funcionament quasi-continu del tractament.
S'ha utilitzat el reactor down-stream i el reactor a pressió atmosfèrica per tal de modificar tres tipus diferents de negre de carboni (N134, XPB 171 i Vulcan XC-72). D'altra banda, s'ha grafititzat i extret el N134 prèviament a la modificació per tal de realitzar un estudi sobre la influència de l'estructura superficial així com també de la presència d'impureses sobre la superfície del NC. L'oxidació i l'augment de nitrogen en superfície han estat les dues modificacions que s'han estudiat principalment per tal de comparar el resultat obtingut per les tècniques presentades.
El NC s'ha caracteritzat mitjançant diverses tècniques analítiques per tal de poder obtenir informació sobre els canvis produïts durant la modificació per plasma. Aquestes tècniques inclouen superfície específica, XRD, WAXS, STM per tal d'estudiar els canvis en la seva morfologia i estructura de la superfície. D'altra banda, per tal d'estudiar els canvis en la composició química s'han emprat mesures de pH, valoracions àcid/base i XPS.
Finalment, alguns dels negres de caboni modificats han estat seleccionats per tal de ser avaluats en aplicacions finals tal i com són el reforçament d'elastòmers i la seva activitat vers la reducció d'oxigen utilitzada en les PEMFC per tal d'eliminar els metalls nobles. En el primer cas, s'ha estudiat l'efecte sobre la cinètica i el mecanisme de vulcanització del negre de carboni modificat mitjançant el plasma atmosfèric. Aquest estudi s'ha dut a terme utilitzant dues tècniques complementaries com són les corbes reomètriques i la vulcanització de molècules model (MCV). També s'han realitzat mesures d'adsorció de polímer sobre el NC i Bound Rubber per tal d'estudiar la interacció polímer-càrrega la qual presenta una gran influència en les propietats finals dels materials. D'altra banda, s'ha estudiat també la capacitat del NC modificat vers a la reducció d'oxigen a partir de voltametria cíclica i s'han determinat les propietats del NC que poden influir de manera rellevant en l'activitat cataítica final del NC per a aquesta reacció. Tot i que es necessari fer una preparació posterior al tractament de plasma per a aquesta aplicació, el material final pot contribuir notablement a la eliminació de metalls nobles com a catalitzadors de reducció d'oxigen en les Piles de Combustible.
The present works deals with plasma modification of carbon black (CB). Although this type of treatment is widely used on flat surfaces handling problems should be overcome in order to treat powders as CB. In this study CB has been modified both by means of low-pressure and atmospheric pressure non-equilibrium plasmas. In order to accomplish this objective three different plasma reactors have been set-up; two at low pressure and one at atmospheric pressure working conditions.
Low pressure plasma reactors utilised in this work consist in a down-stream and a fluidised bed system working at Radio Frequency generation power (RF 13,56 MHz). Both reactors have been optimized to treat powder materials. For the down-stream reactor, position of the reactive gas inlet, and treatment conditions such as generator power and time have been studied for oxygen, nitrogen and ammonia treatments. For the fluidized bed reactor the distance of the powder sample to the plasma generation zone, particle size and support porosity have been taken into account.
Concerning atmospheric plasma, a device has been set up in order to adapt a commercial plasma torch (Openair® from Plasmatreat GmbH), for powder modification. An adaptable reactor, a method to introduce the powder in the plasma zone as well as a collecting system had been developed in order to obtain a quasi-continuous modification treatment.
Three types of CBs, N134, XPB 171 and Vulcan XC-72 have been modified in both the down-stream and the atmospheric plasma system. Graphitization and extraction of N134 were also carried out before plasma modification in order to study the effect of both impurities and surface structure of the CB during plasma modification. Surface oxidation and nitrogen enrichment were the two main studied treatments in both systems which allowed comparing their performances.
Unmodified and Modified CBs have been characterised from several points of view. Specific surface area, XRD, WAXS and STM have been used in order to study morphological and surface structure changes. On the other hand, pH measurements, acid/base titration and XPS were employed in order to study the surface chemistry composition changes that had taken place during plasma modification.
Some of the modified CB grades were selected in order to be tested in final applications such as rubber reinforcement and oxygen reduction non-noble metal catalyst for PEMFC. In the first case, the effect of atmospheric plasma treatment on the vulcanization kinetics and mechanism has been evaluated both by rheometre curves and the model compounding approach. Studies about the polymer-filler interaction have been also carried out by calculating bound rubber and adsorption from polymer solution. Last but not least, plasma modification capacity to enhance the oxygen reduction activity to obtain non-noble metal catalysts for PEMFC has been evaluated after the correspondent preparation. Oxygen reduction activity has been studied by means of cyclic voltammetry. The main CB properties which could play an important role in such applications have been analyzed.
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BELLI, ALBERTO. « Comparison between Commercial and Recycled Carbon-Based Fillers and Fibers for the Development of Smart and Sustainable Multifunctional Mortars ». Doctoral thesis, Università Politecnica delle Marche, 2019. http://hdl.handle.net/11566/263335.
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La società moderna è in gran parte fondata sulle infrastrutture che garantiscono la fornitura di beni, trasporti e mezzi di comunicazione. La loro salvaguardia e il risparmio delle risorse necessarie per il loro funzionamento è di crescente importanza per l’Ingegneria civile. Per questo motivo, la ricerca sui materiali da costruzione si sta concentrando sul riutilizzo di sottoprodotti industriali riciclati, per un’industria edilizia più sostenibile. L’Ingegneria dei materiali, grazie al recente sviluppo di nanomateriali ad alte prestazioni, propone molteplici spunti per la realizzazione di materiali strutturali multifunzionali.
La presente ricerca mira a sviluppare compositi multifunzionali a base di leganti idraulici, con l'aggiunta di filler e fibre a base di carbonio di origine riciclata, ottenuti da sottoprodotti industriali. Sono stati studiati i miglioramenti in termini di resistenze meccaniche e di durabilità, nonché le loro proprietà disinquinanti e fotocatalitiche. Le proprietà elettriche delle miscele sono state studiate, per la valutazione delle capacità di schermatura delle interferenze elettromagnetiche delle aggiunte, e come base di studio per lo sviluppo di materiali auto-sensibili per il monitoraggio strutturale.
Sono state realizzate paste e malte contenenti grafene o altri filler a base di carbonio di origine riciclata (da 0.25 a 4% sul peso del legante) e fibre di carbonio (da 0.05 a 1.6% sul volume della miscela).
Sui composti sono stati eseguiti test di resistenza meccanica e durabilità, nonché test di adsorbimento degli inquinanti, di fotocatalitisi e di resistività elettrica. La sensibilità elettrica alla deformazione è stata valutata misurando la variazione percentuale della resistività su provini soggetti a carichi di compressione semi-statici.
I risultati mostrano che l’aggiunta di filler a base di carbonio riciclati porta a un raffinamento della microstruttura della matrice e a un incremento delle resistenze meccaniche, nonché a un decremento della permeabilità all’acqua. L’aggiunta di micro-fibre di carbonio riciclate porta a un incremento delle resistenze meccaniche a flessione, e a un notevole aumento della conducibilità elettrica (di svariati ordini di grandezza, rispetto ai tradizionali materiali cementizi).Today's society is largely based on infrastructures that guarantee goods, transport and communication networks. Their safeguarding and saving of resources for their operation is becoming increasingly important in the field of building engineering. For this reason, research on building materials is increasingly focused on the re-use of recycled industrial by-products, for a more sustainable construction industry. Materials engineering, thanks to the development of high performance nanomaterials, offers several ideas for the construction of multifunctional building materials. The present research aims to develop multifunctional hydraulic binder-based composite with the addition of recycled carbon-based fillers and fibers obtained from industrial by-products. The enhancement of mechanical strength and durability of the composites have been studied, together with their de-polluting and photocatalytic properties. The electrical properties of the mixtures have been studied to analyze the Electromagnetic interference shielding capability of carbon-based admixtures, and to provide a basis for the development of strain-sensing materials for structural health monitoring. Pastes and mortars containing graphene or other commercial and recycled carbon-based fillers (from 0.25 to 4.0% on binder weight) and fibers (from 0.05 to 1.6% by mixture volume) were realized. Tests of mechanical resistance and durability were performed on the mixtures, together with test of pollutants adsorption, photocatalysis and electrical resistivity. Strain-sensitivity has been evaluated by measuring the fractional change in resistivity of the specimens subjected to quasi-static compressive loads. Results show that the addition of recycled carbon-based fillers leads to a refinement of the matrix microstructure, increasing the mechanical strength and decreasing the water permeability. The addition of recycled carbon micro-fibers leads to an increase in flexural strengths and to a noticeable increase in electrical conductivity (up to several orders of magnitude compared to the traditional cementitious materials).
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Houdek, Aleš. « Návrh postupu svařování ložiskové konzoly ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228733.
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The thesis deals with a draft production procedure for a specific welded component of a bearing console, including the consideration of the basic material welding quality, the selection of welding method and parameters, thermal processing, if applicable, and the selection of filler material. Draft welding procedure of WPS and weld check. Consideration of the use of a robot.
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Yang, Guanda [Verfasser], Dirk [Akademischer Betreuer] Schubert, Fritjof [Akademischer Betreuer] Nilsson, Dirk [Gutachter] Schubert, Fritjof [Gutachter] Nilsson, Georg [Gutachter] Fischer et Kyle [Gutachter] Webber. « Big Data Analysis and Simulation Platform for Anisotropic Electrically Conductive Composites -Validation Utilizing PMMA and Carbon Filler / Guanda Yang ; Gutachter : Dirk Schubert, Fritjof Nilsson, Georg Fischer, Kyle Webber ; Dirk Schubert, Fritjof Nilsson ». Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2021. http://d-nb.info/1228214735/34.
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Meininghaus, Thomas. « Beitrag zum induktiven Löten von Stählen mit unterschiedlichen Kohlenstoffgehalten ». Doctoral thesis, Universitätsbibliothek Chemnitz, 2001. http://nbn-resolving.de/urn:nbn:de:swb:ch1-200100860.
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Das Löten wird als ein Fügeverfahren charakterisiert, bei dem die thermische Beeinflussung der Fügepartner minimal ist. Gleichzeitig ist damit jedoch der prinzipielle Mangel einer Lötverbindung verbunden, denn durch den Verzicht auf das Aufschmelzen des Grundwerkstoffs erreichen die Festigkeiten in der Regel nicht die der Grundwerkstoffe. Diesem Mangel läßt sich einerseits durch Überlapp- oder Steckverbindungen begegnen andererseits bilden sich bei sehr kleiner Lötspaltbreiten ( < 0,02 mm) und in Verbindung mit einem geeigneten Lot-Grundwerkstoff-System sog. Stengelkristallite aus, die über die Lötnaht wachsen und die Festigkeit des Lötverbundes nachhaltig verbessern.
Es wird ein Konzept vorgestellt, mit dem der Anwendungsbereich der Stengelkristallite auf industrieübliche Lötspaltbreiten von bis zu 0,2 mm ausgebreitet wird. Die theoretischen Grundlagen werden durch umfangreiche Versuchsplanung und -durchführung bestätigt. Die Bewertung dieses Verbindungstyps im Vergleich zu Verbindungen ohne Stengelkristallite wird in umfangreichen statischen und dynamischen Festigkeitsuntersuchungen dargelegt. Metallographische Untersuchungen bestätigen den Einfluss auf die Festigkeitserhöhung.
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Ivanoska-Dacikj, Aleksandra, Gordana Bogoeva-Gaceva, René Jurk, Sven Wießner et Gert Heinrich. « Assessment of the dynamic behavior of a new generation of complex natural rubber-based systems intended for seismic base isolation ». Sage, 2017. https://tud.qucosa.de/id/qucosa%3A35604.
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This work, conceived as a second step in the development of high-performance damping materials suitable for seismic application, describes the preparation and characterization of complex natural rubber-based composites containing hybrid nano- and conventional fillers. The cluster–cluster aggregation model was used to assess the apparent filler networking energy. The values obtained suggested that the presence of the hybrid nanofiller strengthens the filler networking. The same model was used to understand the mechanisms of energy dissipation. The damping coefficient was found to be in the sought range between 10% and 20% (at 0.5 Hz and high shear strain).
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Satam, Sayali S. « Optimization of Wet Friction Systems Based on Rheological, Adsorption, Lubricant and Friction Material Characterization ». University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1503358825451407.
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Yin, Xunqian. « Modification of electrostrictive polymers and their electromechanical applications ». Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0041/document.
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Les polymères électroactifs (PAE), sont des matériaux permettant de réaliser une conversion entre l'énergie électrique et mécanique. L'objet de ce travail est de proposer des procédés de modifications des terpolymères électrostrictifs par voies composites basés sur différentes approches dans le but d’améliorer les performances électromécaniques et de développer des applications à partir de ces matériaux modifiés. Dans un premier temps, un nano-composite à base de terpolymère et de noir de carbone a été préparé pour améliorer la permittivité diélectrique. Dans un deuxième temps, sur la base de la nature hétérogène de terpolymère semi-cristallin ainsi que du rôle important que la polarisation interfaciale joue sur la réponse diélectrique et électromécanique, une faible quantité d’agent plastifiant (bis (2-ethylhexyl) phalate (DEHP)) a été introduite dans le terpolymère électrostrictif afin de former un composite tout organique permettant l'amélioration des performances électromécaniques. Enfin, l’utilisation de ces matériaux modifiés dans deux applications spécifiques a été étudiée: La récupération de l'énergie mécanique et une pompe microfluidique sans valveElectroactive polymers (EAPs), which can realize the conversion between electrical and mechanical energy, have been emerging as one of the most interesting smart materials in the past two decades due to their low density, excellent mechanical properties, ease of processing, low price and potential applications in the fields of sensors, actuators, generators, biomimetic robots and so on. The object of this work is to modify electrostrictive terpolymers with different approaches to improve the electromechanical performances and to develop some applications based on modified terpolymers. Firstly, an organic/inorganic (terpolymer/carbon black) nanocomposite was prepared to improve the dielectric permittivity based on the percolation theory. Secondly, based on the heterogeneous nature of semi-crystalline terpolymer and the important role that interface polarization plays for dielectric and electromechanical response, small molecular plasticizer bis(2-ethylhexyl) phalate (DEHP) was introduced into electrostrictive terpolymer to form an all-organic polymer composite with improved electromechanical performances. Finally, two applications including mechanical energy harvesting and microfluidic pump based on DEHP modified terpolymers were investigated
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Vidhate, Shailesh. « Piezoresistive Polyvinylidene Fluoride/Carbon Filled Nanocomposites ». Thesis, University of North Texas, 2011. https://digital.library.unt.edu/ark:/67531/metadc68059/.
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This thesis examines the value of using dispersed conductive fillers as a stress/strain sensing material. The effect of the intrinsic conductivity of the filler on the ability to be effective and the influence of filler concentration on the conductivity are also examined. To meet these objectives, nanocomposites of polyvinylidene fluoride (PVDF) with carbon nanofibers (CNFs) and carbon nanotubes (CNTs) were prepared by melt-blending using a twin screw extruder. Since PVDF has a potential to be piezoresistive based on the type of crystalline phase, the effect of CNFs on PVDF crystallinity, crystalline phase, quasi static and dynamic mechanical property was studied concurrently with piezoresponse. Three time dependencies were examined for PVDF/CNTs nanocomposites: quasi-static, transient and cyclic fatigue. The transient response of the strain with time showed viscoelastic behavior and was modeled by the 4-element Burger model. Under quasi-static loading the resistance showed negative pressure coefficient below yield but changed to a positive pressure coefficient after yield. Under cyclic load, the stress-time and resistance-time were synchronous but the resistance peak value decreased with increasing cycles, which was attributed to charge storage in the nanocomposite. The outcomes of this thesis indicate that a new piezoresponsive system based on filled polymers is a viable technology for structural health monitoring.
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Yue, Liang. « EPOXY COMPOSITES WITH HYBRID CARBON FILLERS ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1387167480.
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Mada, Mykanth Reddy Materials Science & Engineering Faculty of Science UNSW. « Fabrication and characterisation of SWCNT-PMMA and charcoal-PMMA composites with superior electrical conductivity and surface hardness properties ». Awarded by:University of New South Wales. Materials Science & ; Engineering, 2009. http://handle.unsw.edu.au/1959.4/41831.
Texte intégralRésumé :
Fabrication of SWCNT-PMMA and Activated Charcoal- PMMA composites was carried out by the compression moulding technique. Then Mechanical and Electrical properties of the composites were investigated. The morphological studies of composites showed a) good dispersion of fillers and b) good interaction between fillers and matrix. Electrical conductivity of SWCNT-PMMA composites was increased by 9 orders of magnitude (at 0.8 % volume fraction of SWCNT) and that of AC-PMMA composites increased by 16 orders of magnitude (at 17 % volume fraction of AC). The percolation threshold of both composites turned out to be lower compared to the theoretical values. A significant improvement in mechanical properties was obtained ??? particularly in AC-PMMA composites which showed a 400 % improvement in Vickers microhardness ??? raising the polymer matrix abrasion property literally to that of Aluminium alloys (Dobrazanski et al 2006). In conclusion, it is to be noted that Activated Charcoal - PMMA composites have a great potential for cost effective conducting polymer composite production by the use of cheap filler: In addition, the compression moulding technique shows good potential for cost effective fabricating technique for amorphous polymers with high electrical and mechanical properties.
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Costa, Elisabete Fernandez Reia Da. « Liquid moulding of carbon nanoparticle filled composites ». Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7276.
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This thesis focuses on the incorporation of carbon nanoparticles within continuous fibre reinforcements by liquid composite moulding processes, in order to provide enhanced electrical and delamination properties to the multiscale composites. The mechanisms controlling the flow and filtration of these nanoparticles during liquid composite moulding are studied, in order to develop a predictive 1-D model which allows design of the processing of these composite materials. Five different carbon nanoparticles at 0.25 wt% loading, three unmodified and one surface modified carbon nanotube systems and one carbon nanofibre system, were utilised to modify a commercial two-component epoxy resin utilised to impregnate carbon and glass reinforcements at high fibre volume fraction by resin transfer moulding. The dispersion of the nanofillers in the prepolymer was carried out by ultrasonication, high shear mixing or triple roll milling or a combination of the three. Electrical conductivity measurements of the carbon nanoparticle liquid suspensions during dispersion, alongside optical microscopy imaging and rheological analysis of these allowed the selection of the concentration of nanofiller and the appropriate dispersion technique for each nanoparticle system. The resin transfer moulding process required adaptation to incorporate the dispersion and modify degassing steps, especially when utilising unmodified carbon nanoparticles suspensions, due to their higher viscosity and tendency to be filtered. Nanoparticle filtration was identified by electrical conductivity measurements and microscopy of specimens cut at increasing distances from the inlet. Cake filtration was observed for some of the unmodified systems, whereas deep bed filtration occurred for the surface modified CNT material. Property graded composites were obtained due to filtration, where the average electrical conductivity of the carbon and glass composites produced increased by a factor of two or one order of magnitude respectively. The effect of filler on the delamination properties of the carbon fibre composites was tested under mode I. The results do not show a statistically significant improvement of delamination resistance with the presence of nanoparticles, although localised toughening mechanisms such as nanoparticle pull-out and crack bridging as well as inelastic deformation have been observed on fracture surfaces. Particle filtration and gradients in concentration resulted in non-linear flow behaviour. An 1-D analytical and a finite difference model, based on Darcy’s law accompanied by particle mass conservation and filtration kinetics were developed to describe the flow and filtration of carbon nanoparticle filled thermosets. The numerical model describes the non-linear problem by incorporating material property update laws, i.e. permeability, porosity and viscosity variations on concentration of retained and suspended particles with location and time. The finite difference model is consistent and converges to the analytical solution. The range of applicability of the analytical model is limited to lower filtration coefficients and shorter filling lengths, providing an approximate solution for through thickness infusion; whereas the numerical model presents a solution outside this range, i.e. in-plane filling processes. These models allow process design, with specified carbon nanoparticle concentration distributions achieved via modifying the nanofiller loading at the inlet as a function of time.
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Vlandas, Alexis S. D. « Structure and properties of filled carbon nanotubes ». Thesis, University of Oxford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526423.
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Murki, Sai Rohith, et Yaswanth Puttagunta. « CFD Simulation of an Activated Carbon Filter ». Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13839.
Texte intégralRésumé :
In various industries, specialized filters with activated carbon are used for adsorbing mercury from air-flows. MRT has eight such Activated CarbonFilters (ACFs) in one of their devices. The main purpose of research is tostudy the flow in the ACF filter and suggest a mathematical model for the complete system through which an improved design can be found.Simulation of a single ACF illustrates how the current system’s air flow does not cover the whole filter leaving part of the carbon bed unused forthe adsorption. This is validated by experimental data. A theoretical studybased on a mathematical model is made and the improved air flow pattern of a re-designed ACF is presented. An additional improvement is that byswitching inlet and outlet the usable time of the filters is prolonged.
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Parris, Donald R. « Electrical characterization of carbon black filled rubber ». Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91055.
Texte intégralRésumé :
DC resistance and AC conductance and capacitance have been measured under various conditions in an effort to electrically characterize and make electrical-mechanical correlations for 15 carbon black filled rubber samples.
Resistance, conductance and capacitance have been monitored as functions of uniaxial compressive stress, time, temperature, and mechanical and thermal history. Capacitance and conductance have also been monitored as functions of frequency under various degrees of compressive loading and before and after specific heat treatments.
A direct relationship has been found between sample • conductance and capacitance under any thermal and/or mechanical condition. This is in agreement with previous theories of conduction network formation and percolation. Various conduction mechanisms have been enumerated and an equivalent circuit of a network of lumped R-C "microelements'' has been qualitatively described. Stress, relaxation, frequency, and temperature dependences of the macroscopic parameters measured ( conductivity and capacitance) are discussed in terms of this model.M.S.
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Frébourg, Philippe. « Mélanges noir de carbone-polybutadiène : étude par RMN du proton, extraction et gonflement ». Université Joseph Fourier (Grenoble), 1994. http://www.theses.fr/1994GRE10205.
Texte intégralRésumé :
Les systemes etudies sont constitues d'agregats de noir de carbone n220 interconnectes par des chaines polybutadiene absorbees a leur surface. Nous les caracterisons par extraction, rmn et gonflement. Les mesures du taux de polymere residuel apres extraction et la modelisation de l'adsorption par la percolation nous permettent d'estimer la proportion de chaines faiblement fixees et desorbees lors du sejour en solvant. D'autre part, les proprietes rmn de ces systemes conduisent a une caracterisation fine de la statistique d'adsorption sur differentes echelles d'espace: au niveau de l'interface charge-polymere, nous mettons en evidence une proportion de monomeres adsorbes remarquablement faible, de l'ordre de 2%. Au niveau de l'interphase, nous montrons que la structure en boucles des chaines adsorbees depend fortement de l'histoire des echantillons. En fin d'extraction et avant sechage cette structure est tres lache et le nombre de points d'absorption par chaine est independant de leur longueur. Par contre, apres sechage l'interphase s'est densifiee de facon irreversible et ce nombre devient proportionnel a la racine carree de la longueur des chaines. Enfin, le gonflement, decrit dans l'approche en champ moyen de flory, apporte des informations complementaires sur la texture des melanges. L'ensemble des resultats experimentaux obtenus conduit a une representation globale et coherente de l'organisation microscopique de ces systemes
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Ciuk, Karlsson Susanna. « Modeling of bark-, sand- and activated carbon filters for treatment of greywater ». Thesis, Energi och Teknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-187078.
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ABSTRACT Modeling of bark-, sand- and activated carbon filters for treatment of greywater Susanna Ciuk Karlsson The part of the waste water produced in a household, originating from showers, dish - and wash water, is called greywater. It is possible to treat the greywater separately from the black water (toilet water) as it is less polluted and then use it for purposes such as garden irrigation. There are various methods for purifying greywater. Here, the possibility to purify greywater using three column filters with different materials (activated carbon, pine bark and sand) was examined through modeling in the computer program HYDRUS. A set-up with physical filters was available, where flow measurements were performed. These measurements were used to validate the model that was developed in HYDRUS. When a flow model had been produced that could replicate the measured flow, a module of HYDRUS was used to also model the reactive transport of nutrients and organic matter in the filters. The complete model was used for evaluation of the treatment performance of the filters during a default scenario where they were loaded with 1 liter of water per day containing pollutant concentration corresponding to typical greywater.REFERAT Modellering av bark-, sand- och kolfilter för rening av BDT-vatten Susanna Ciuk Karlsson I ett hushåll används vatten som då blir till avloppsvatten. Detta avloppsvatten består till stor del av bad, disk och tvättvatten (BDT-vatten). Det är möjligt att behandla BDT-vattnet separat från klosettvattnet då det är mindre förorenat, låta det genomgå rening och sedan använda det för till exempel bevattning av trädgårdar. Det finns olika metoder för att rena BDT-vatten. Här studerades möjligheterna att rena BDT-vatten med hjälp av tre filter av olika material; aktivt kol, tallbark och sand, genom modellering i datorprogrammet HYDRUS. En praktisk experimentuppsättning med filterkolonner fanns att tillgå, där ett experiment med flödesmätningar genomfördes. Mätningarna användes för att validera modellen som utvecklades i HYDRUS. Efter att en flödesmodell som stämde överrens med uppmätta värden utvecklats, modellerades reaktiv transport av näringsämnen och organiskt material i filtren med en modul tillhörandes HYDRUS. Med hjälp av modelleringen kunde filtertypernas reningsförmåga utvärderas för ett iscensatt standardscenario där filtrena belastades med 1 l vatten/dag innehållandes föroreningar motsvarandes ett typiskt gråvatten.
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Hudziak, Stephen. « Iron-filled carbon nanotubes : Synthesis, characterisation and applications ». Thesis, Queen Mary, University of London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528419.
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Thompson, Timothy V. « Solid-state NMR studies of absorption onto activated carbon ». Thesis, Durham University, 1995. http://etheses.dur.ac.uk/5228/.
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This is a study of adsorption on three activated carbon substrates using solid- state NMR. The adsorbates used as probe molecules included a range of phosphates, phosphonates and deuterated water. High-resolution (^31)p and (^2)H NMR spectra have been obtained using magic-angle spinning and a single-pulse regime. The deuterium results include the generation of an adsorption isotherm. The traditional gravimetric analysis and NMR experiments were run concurrently. These results showed that the NMR technique was qualitatively and quantitatively accurate, while the proven adsorption isotherm theory could be applied to the NMR results. The additional information given by the (^2)H NMR results showed evidence of two distinct adsorption sites. Initial adsorption in the micropores gives a peak shifted by 6 ppm to low frequency of the liquid (^2)H(_2)O. This peak was broadened due to restricted motion in the micropores. The second peak was observed only at high relative humidities and was attributed to adsorption on the external surface or in macropores. The chemical shift was similar to that of the pure liquid. The (^31)p NMR results were used to directly observe the adsorption of phosphates with a range of molecular sizes. The NMR data were used to calculate the micropore accessibility for each phosphate. Differences in the adsorption mechanism were recorded, and direct comparison for each carbon gave some structural information. It was possible to follow competition reactions over time periods of 1 min to 24 hours. A battlefield simulation was studied, with (^2)H(_2)O and a phosphate competing for the adsorption sites. The NMR results showed that the phosphate was preferentially adsorbed into the micropores, displacing the (^2)H(_2)O However, the addition of (^2)H(_2)O to a carbon saturated with a phosphate enabled more phosphate to be adsorbed into the micropores via a cooperative mechanism. Measurements of the transverse relaxation for adsorbed molecules suggest that the broad micropore signal consists of some overlapping peaks. The peaks width similar chemical shift are attributed to adsorption in pores with differing dimensions. The natural linewidth involves broadening caused by restricted anisotropic motion within the micropores.
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Jones, Kristopher Neil. « An Exploration of Carbon-Filled Carbon Nanotubes as a Potential Material in Coronary Stents ». BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3785.
Texte intégralRésumé :
The purpose of this research is to explore the potential of using carbon-infiltrated carbon nanotubes (CI-CNT) as a material for coronary artery stents. Stents are commonly fabricated from metal, which may not perform as well as many polymers and ceramics in biomedical applications. Pyrolytic carbon, a ceramic, is currently used in medical implant devices due to its preferrable biocompatibility properties. Micro-patterned pyrolytic carbon devices can be created by growing carbon nanotubes, and then filling the space between with amorphous carbon via chemical vapor deposition. We prepared multiple samples of two different planar stent-like flexible geometries and smaller cubic structures out of carbon infiltrated carbon nanotubes. These samples were tested in tension to failure. The cubic structures were used for separate compression tests. We also examined existing auxetic patterns for possible application in the stent designs and a second iteration of design and fabrication was performed using data and understanding obtained from the work in the first iteration. Slight changes were made to the mask design and fabrication processes based on the new geometries and testing considerations. The auxetic planar designs were tested in compression to demonstrate flexibility and collect material data. The testing results show that CI-CNTs can be designed and fabricated into flexible geometries capable of stent-like compression. The samples in this work were found to have moduli ranging from 5 to 27 GPa, with the majority being between 10 and 20 GPa. We also found fracture strength greater than 100 MPa, with it sometimes getting as high as 200 MPa. Lastly, fracture strain values were measured, with the maximum reaching 1.4% and the average between 0.75-1%. We also found that the CI-CNTs material lends itself to fracture at weak locations (if present) before the anticipated fracture strength has been reached and concluded that a tightly controlled process (including fabrication machines) environment is necessary to ensure consistent results and a CI-CNT material whose imperfections have been minimized.
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Torres, Dias Abraao Cefas. « Effects of high pressure on empty and water-filled single-wall carbon nanotubes studied by Raman spectroscopy ». Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10283/document.
Texte intégralRésumé :
La présente thèse est constituée par un ensemble d'études expérimentales sur l'effet des hautes pressions sur les nanotubes de carbone mono-parois, individualisées, fermés ou ouvertes, donc vides ou remplis d'eau. Les techniques des hautes pressions et de la spectroscopie Raman ont été combinées afin d'étudier l'effondrement des nanotubes et de sonder les modifications induites par l'effet de la pression. Les coefficients de pression des modes radiaux de respiration (RBM) ont été obtenus avec identification individuelle par chiralité. Les RBM des nanotubes remplis d'eau ont pu être observés à des pressions bien plus élevées que pour des nanotubes vides. Après un cycle à haute pression, les nanotubes vides de diamètre plus important n'étaient pas détectables tandis que les tubes de diamètre sous-nanométrique se sont remplis d'eau. Ces observations suggèrent que les nanotubes de diamètre le plus faible ont une meilleur stabilité sous pression qui est accrue par le remplissage par de l'eau. Une réponse inusuelle du nanotube (7,2) suggère que la chiralité peut avoir aussi un rôle aussi important dans la stabilité structurelle, en tout cas pour les nanotubes de plus faibles diamètres. De son côté, l'évolution des modes de vibration tangentiels suggère l'effondrement radial des nanotubes vides d'un diamètre d'environ de 1.32 nm à une pression proche de 4 GPa, en accord avec les prévisions théoriques les plus récentes. Ces mêmes tubes remplis d'eau, présentent un effondrement à une pression qui se situe au-delà de 16 GPaThe present thesis constitutes a set of experimental studies on the effect of high pressures on single wall carbon nanotubes, individualized, closed or open, therefore empty or filled with water. High-pressure techniques and Raman spectroscopy were combined to study the radial collapse, as well to probe the pressure-induced modifications. Chirality-resolved pressure derivatives were obtained for the radial breathing modes (RBM). The RBM of water-filled could be observed at pressures higher than those of empty. After a high-pressure cycle, empty nanotubes of larger diameters were not detectable anymore, while sub nanometric diameter ones became filled with water. Such observations suggest that thinner nanotubes have better pressure-stability, which is increased upon water filling. An unusual response of the (7,2) nanotube suggests that the chirality may have also an important role on the structural stability for small diameters. The evolution of the tangential modes suggest the onset of radial collapse of empty nanotubes averaging 1.32 nm diameter at about 4 GPa, in agreement with the latest theoretical predictions. These same nanotubes, though water-filled, they collapse at pressures higher than 16 GPa
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Golightly, John. « Characterization of a carbon radon filter and Radon detection ». Thesis, Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1397.
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Lin, Tsung-Wu. « Physical properties and potential applications of filled carbon nanotubes ». Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442602.
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Weißker, Uhland. « Synthesis and mechanical properties of iron-filled carbon nanotubes ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-135707.
Texte intégralRésumé :
Carbon forms the basis of a variety of compounds. The allotropic forms of carbon include graphene, fullerenes, graphite, carbon nanotubes and diamond. All these structures possess unique physical and chemical properties. This work focusses on the usage of carbon nanotubes (CNT), especially iron-filled CNT.
An industrial application of CNT requires the understanding of the growth mechanism and the control of the synthesis process parameters. Regarding iron-filled CNT the shell formation as well as the filling process has to be understood in order to control the CNT morphology and distribution and dimension of the iron filling. The thesis involves two topics - synthesis of CNT and characterization of their mechanical properties. Chapter 2 of the present work deals with the synthesis of iron-filled CNT. In this thesis all experiments and the discussion about the growth process were conducted with respect to the demands of magnetic force microscopy probes.
The experimental work was focused on the temperature profile of the furnace, the aluminum layer of the substrate, the precursor mass flow and their impact on the morphology of in-situ iron-filled CNT. By selecting appropriate process parameters for the temperature, sample position, gas flow and by controlling the precursor mass flow, CNT with a continuous filling of several microns in length were created.
Existing growth models have been analyzed and controversially discussed in order to explain the formation of typical morphologies of in-situ filled CNT. In this work a modified growth model for the formation of in-situ filled CNT has been suggested. The combined-growth-mode model is capable to explain the experimental results. Experiments which were conducted with respect to the assumptions of this model, especially the role of the precursor mass flow, resulted in the formation of long and continuous iron nanowires encapsulated inside multi-walled CNT. The modified growth model and the synthesis results showed, that besides the complexity of the parameter interaction, a control of the morphology of in-situ iron-filled CNT is possible.
In chapter 3 the measurements of mechanical properties of in-situ iron-filled CNT are presented. Two different experimental methods and setups were established, whereby one enabled a static bending measurement inside a TEM and another a dynamical excitation of flexural vibration of CNT inside SEM.
For the first time mechanical properties and in particular the effective elastic modulus Eb of in-situ iron-filled CNT were determined based on the Euler-Bernoulli beam model (EBM). This continuum mechanic model can be applied to describe the mechanical properties of CNT and especially MWCNT in consideration of the restriction that CNT represent a macro molecular structure built of nested rolled-up graphene layers. For evaluation and determination of the elastic modulus the envelope of the resonant vibrating state was evaluated by fitting the EBM to the experimental data. The experiments also showed, that at the nanoscale the properties of sample attachment have to be taken into account.
Thus, instead of a rigid boundary condition a torsion spring like behavior possessing a finite stiffness was used to model an one side clamped CNT. The extended data evaluation considering the elastic boundary conditions resulted in an average elastic modulus of Eb = 0.41 ± 0.11 TPa. The low standard deviation gives evidence for the homogeneity of the grown material. To some extend a correlation between the formation process, the morphology and the mechanical properties has been discussed. The obtained results prove the usability of this material as free standing tips for raster scanning microscopy and especially magnetic force microscopy. The developed methods provide the basis for further investigations of the CNT and the understanding of mechanical behavior in greater detail.
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Lucchese, Laurence. « High temperature stabilisation of carbon black filled natural rubber ». Thesis, Manchester Metropolitan University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310622.
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TRAVAGLIA, PAOLO. « Dielectric and EM properties of carbon filled epoxy resin ». Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/859.
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Questa tesi riguarda le proprietà dielettriche e di assorbimento alle microonde della resina epossidica caricata di nanocariche. Tre differenti nanocariche a base di carbonio sono state usate in questa tesi: Carbon black (CB) nanofibre di carbonio (CNF) e nanotubi di carbonio (CNT). Inoltre,sono stati provati vari processi di dispersione delle nanocariche nella resina, per analizzare gli effetti della distribuzione delle nanocariche sulle proprietà dielettriche dei composti che ne risultavano. È stata misurata la permettività usando un sistema VNA nella banda-X (8,2-12,4 GHz) usando il metodo della guida d’onda. La morfologia dei campioni è stata studiata con un sistema FEG-SEM. usando il modello del circuito equivalente è stata tentata una connessione tra la morfologia dei campioni e la permettività. Infine si è giunti alla conclusione se questi materiali sono adatti ad essere usati come materiali che assorbenti le microonde elettromagnetiche.
Nei campioni di CB, realizzati usando cariche con differenti aree di superficiali specifiche la distribuzione delle cariche nella resina é differente, quando si usano cariche di alta area di superficiale producendo piccoli corti clusters ramificati, e nell’altro caso aggregati lunghi spessi e serpeggianti. In entrambi i casi i clusters sono vicini a una forma cilindrica e possono essere visti come condensatori a cilindri paralleli, immersi nella resina. Di conseguenza, i campioni di alta area di superficie presentano valori più bassi di permettività reale (misura la capacita del sistema), dovute alla minore lunghezza dei clusters (armature dei condensatori), ma una maggiore permettività immaginaria (legata agli effetti della conduttività e della dispersione) perché come è stato fatto notare precedentemente i clusters sono disposti in maniera molto ravvicinata permettendo l’attivazione di modelli di conduzione hopping and tunnelling. i campioni CB hanno dimostrato buoni risultati come assorbitori di EM raggiungendo un picco di 38dB usando un campione spesso 4mm.
Nei campioni caricati con cariche con alto aspect ratio (CNF e CNT) il parametro principale è la loro dispersione nella resina,nelle prove con campioni caricati con CNF, nonostante l’uso di metodologie differenti,è stata raggiunta una dispersione non soddisfacente,con la microstruttura risultante composta di aggregati. Le misurazioni EM hanno messo in luce che maggiore il numero e più piccola la dimensione degli aggregati,maggiori sono ε’ e ε” per la stessa ragione trovata nel caso dei campioni caricati con CB. Nel caso dei campioni CNT, invece una dispersione veramente buona stata raggiunta con l’aiuto di un surfactante ed un sonicatore più potente. I risultati dimostrano di nuovo che la permettività è legata alla microstruttura, con la stessa tendenza stabilita con altri tipi di nanocariche, tuttavia,in questo caso è stata rinvenuto un nuovo caso che mette in luce che c’è un ottimo livello di dispersione sopra quale i CNT non interagiscono tra di loro risultando in un ε’ molto alto e in un ε” molto basso visto che la dispersione attraverso l’effetto Joule è limitata. Le prestazioni di assorbimento di CNF e CNT dimostra che sia una percentuale troppo elevata sia la troppa dispersione porta ad un materiale soprattutto riflettente, con basse prestazioni di assorbimento. Un buon compromesso, perciò ,deve essere trovato per ogni sistema come compromesso tra la composizione del materiale, la microstruttura e lo spessore.
Parte del lavoro sperimentale e stata condotta presso l’università di Monash (Clayton, Victoria Australia) sotto la supervisione del Prof. George Simon.This thesis deals with the dielectric and absorbing properties at microwaves (x-band) of epoxy resin filled nanocomposites. Three different carbonaceous nanofillers were used in the experimental: carbon black (CB), carbon nanofibers (CNF) and carbon nanotubes (CNT). Moreover, various dispersion processes of nanofiller in the resin were tried, in order to analyze the effect of filler distribution on the dielectric properties of the resulting composites. Permittivity was measured using a vector network analyzer in x-band (8,2-12,4 GHz) using the waveguide method. Samples morphology was studied by FEG-SEM. Using the equivalent circuit analogy, a link between samples morphology and permittivity was attempted. The suitability of these materials as electromagnetic microwaves absorbers was finally assessed. In carbon black samples, realized using fillers with different specific surface areas, the filler distribution within the resin is very different, producing small short branched clusters when using high surface areas filler, and long thick and meandering aggregates in the other case. In both samples the clusters are close to cylindrical shape and may be seen as parallel cylinders capacitors in the resin. As a consequence, high surface area samples present lower values of real permittivity (that takes into account capacity of the system), due to the smaller length of capacitor plates, but higher imaginary permittivity (linked to conductivity and dissipations effects) because, as noted above, the clusters are closely spaced, permitting the activation of hopping and tunnelling conduction modes. CB samples showed good performances as EM absorbers, reaching a peak of -38 dB using a sample 4 mm thick. In samples loaded with high aspect ratio (CNF and CNT) the key parameter is their dispersion in the resin. In CNF experimentation, despite the use of different methodologies, an unsatisfying dispersion was achieved, with the resulting microstructure made of aggregates. The EM measurements highlighted that the higher the number and the smaller the dimension of the aggregates, the higher are ε’ and ε”,for the same reason found in the case of CB. With CNT, instead, very good dispersions were achieved, by means of the aid of surfactants and of a more powerful sonicator. The results demonstrate again that permittivity is linked to microstructure, with the same trend established with the other type of nanofillers. Nevertheless, in this case, a new evidence was found highlighting that there is an optimum level of dispersion, above which the CNT do not interact each other, resulting in very high ε’ and very low ε”, since dissipation through Joule effect is limited. The absorbing performance of CNF and CNT demonstrate that too much filler, or too much dispersion of it (i.e. Low ε”), bring to a mostly reflective medium, with low absorbing performance. An optimum formulation needs, therefore, to be found for every system as a compromise among material composition, microstructure and thickness. Part of the experimental work (most of chapter 6 ) was carried out during the author secondment to Monash University (Clayton, Victoria Australia) under the supervision of Prof. George Simon.
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Parham, Hamed. « Ceramic-carbon nanotube composites and their potential applications ». Thesis, University of Exeter, 2012. http://hdl.handle.net/10871/8141.
Texte intégralRésumé :
Carbon nanotubes (CNTs) have been the subject of intensive research for nearly two decades, and this is due to their exceptional lightness, large aspect ratio, extraordinary mechanical, electrical, thermal properties and additional multi-functional characteristics. Ceramics have high stiffness and good thermal stability with a relatively low density, and they are an important constituent in the fabrication of advanced composites where high thermal and chemical stability are important. However, brittleness has limited their application in many structural applications. The combination of ceramic (alumina in particular) and CNTs, endeavouring to develop functional composites, offers a very attractive system for research and development. The fabrication of such alumina-CNT composites at bulk scale is therefore highly desirable for industrial applications. However, the synthesis of such composites possesses many technical challenges which need to be addressed. Poor synergy between the matrix and CNTs, potential damage to CNTs, obtaining a uniform and agglomeration-free distribution of CNTs within the matrix, and high cost of CNTs and processes involved in their composite fabrication have proved to be the significant challenges. In this thesis, the focuses are laid on addressing these issues and on the fabrication of specially engineered composites for particular applications such as filter and composites with improved mechanical properties. In this regard, it has been tried to directly fabricate CNTs in different ceramic matrices based on the application requirements. After that, the critical issues and challenges in the fabrication of these functional materials have been clearly investigated and by introducing novel methods and approaches, it has been tried to solve these problems. Also, a new polymer-ceramic-CNT composite has been fabricated by using two different thermoset (epoxy resin) and thermoplastic (polyamide 12) matrices. In this regard, good interfacial bonding between the composite elements along with good wettability of ceramic and CNTs with polymer had to be addressed as critical issues and challenges in the fabrication process. If the adherence at the interface is not strong enough, the material will tear and fail easier. In contrary, a tailored functionalization of CNTs can lead to an improved wettability and as the results, strong interfacial adhesion and bonding between the composite elements. These dominating factors will improve the degree of filling which results in existence of fewer voids inside the composite. These voids will act later as stress points and reduce the composite strength. At the end, the mechanical properties of the fabricated samples have been assessed. The CNT filters have been tested in the removal of bioorganic (yeast cells) and inorganic (heavy metal ions) contaminants from water, and of particulates from air, and they all showed very promising results. More than 99.6% of the air particles (size ranges from 0.3 to 10 µm) were filtered using 300 mm long CNT filter. A complete removal of heavy metal ions from water was reported particularly for single ion. 98% of the yeast cells were filtered. Different factors involved in the filtration efficiency such as ceramic pore size, length of filters, CNT loading and injection rates have also been discussed. Furthermore, the mechanical properties (compression test, hardness and impact test) of the composite materials (including ceramic-CNT, epoxy resin-ceramic-CNT and polyamide-ceramic-CNT composites) have been assessed. During impact test, the epoxy resin-ceramic-CNT composite absorbed 117.2% and 32.7% more energy compared to the pure epoxy resin and epoxy resin-ceramic composite, respectively. The epoxy resin-ceramic-CNT composite sustained 40% more elastic deformation before breakage compared to the epoxy resin-ceramic composite as a result of the CNT reinforcement. The addition of CNTs to the polyamide12-ceramic composite increased its yield stress by 41%. All of these results represent a big leap towards practical applications for the composite reported in the thesis, which may open up new opportunities for CNT engineering at industrial scales, due to the easy fabrication methods introduced and the promising performance they have exhibited.
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Vadivel, Hari Shankar. « Tribological Behaviour of Hybrid Carbon Filled UHMWPE Composites in Water ». Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-373.
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There is a increasing emphasis in today’s world to use environmental friendly solutions for tribological and lubrication purposes. Use of water as a lubricant presents a cost effective and easy method of bio friendly lubrication. But, as water has low viscosity, it is necessary that the materials used in water lubricated contacts perform exceedingly well in boundary lubricated conditions. Polymer Based Materials (PBMs), are one such group of materials which have been proven to perform well in such conditions. In particular, Ultra High Molecular Weight Polyethylene (UHMWPE) has been extensively used in water lubricated contacts. But, PBMs still suffer from wear and related problems and there is room for improvement. Various methods have been tried with mixed results to improve the qualities of polymers and consequently their performance in water lubricated contacts. One such method is by inclusion of fillers. Conventionally, micron sized fillers have been used to form composites with a polymer resulting in materials with better properties. Recently, nanometer sized reinforcements have been attracting more attention due to their unique mechanical and tribological properties. Combining micrometer and nanometer sized filler in a polymer composite could help form materials with excellent properties. Such composites would be termed as a hybrid material. Therefore, the aim of this project and thesis is to experimentally investigate the influence and interaction of micro and nano carbon-based fillers on tribological behaviour of UHMWPE composites and provide further understanding of the mechanisms involved.
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Pruitt, Landon. « Exploration of a carbon nanotube anode gas-filled radiation detector ». Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1220474463/.
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Deeprasertkul, Chudej. « Dynamic mechanical properties of carbon black filled elastomer containing liquids ». Thesis, Queen Mary, University of London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322321.
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Krückel, Johannes [Verfasser]. « Electrical and Rheological Behaviour of Carbon Black Filled Polymers / Johannes Krückel ». München : Verlag Dr. Hut, 2015. http://d-nb.info/1069019909/34.
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Brown, Gareth. « Structural studies of filled single-walled carbon nanotubes and inorganic fullerenes ». Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270283.
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Philp, Eilidh F. « The synthesis and characterisation of novel filled single-walled carbon nanotubes ». Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398396.
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Fang, Xin. « Carbon Nanoparticle-Filled Polyacrylonitrile Electrospun Stationary Phase for Ultrathin Layer Chromatography ». The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1376995276.
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Zhong, Jing. « Ultrasonically aided extrusion in preparation of polymer composites with carbon fillers ». University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1460413630.
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Souza, André Luis Rocha de. « Perfil do mercado de carbono no Brasil : análise comparativa entre os mercados regulado e voluntário ». Universidade Federal da Bahia, 2012. http://www.adm.ufba.br/sites/default/files/publicacao/arquivo/andre_luis_rocha_de_souza_0.pdf.
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Essa pesquisa teve por objetivo geral investigar as principais diferenças entre o mercado de carbono regulado e voluntário no Brasil, no período de 2004 a 2011. Para alcançar o objetivo proposto, realizou-se uma pesquisa exploratória, de caráter bibliográfica e documental. Além disso, realizou-se o mapeamento de projetos no mercado de carbono voluntário no Brasil por meio de busca em bancos de dados e sites institucionais dos Padrões Internacionais (PIs) e dos proponentes, enquanto que os projetos do mercado de carbono regulado foram extraídos do banco de dados já existente no site do Ministério da Ciência e Tecnologia (MCT). Os dados secundários foram coletados por meio de analise de conteúdo dos Documentos de Concepção dos Projetos (DCP) mapeados e extraídos dos sites e banco de dados visitados. Verificam-se diferenças e semelhanças entre os mercados de carbono regulado e voluntário no Brasil, estando o primeiro mercado com 499 projetos, enquanto o segundo possui 111 projetos até o momento. Constatou-se que o mercado de comercialização de créditos de carbono brasileiro, seja ele na categoria regulada, seja na voluntária pode constituir-se em um instrumento econômico de extrema importância na viabilização da redução das emissões de GEE, contribuindo, assim, para a mitigação das mudanças climáticas e para o alcance das metas nacionais de redução de emissão de GEE fixadas na Política Nacional de Mudanças Climáticas (PNMC). Constatou-se também que o uso desses projetos como instrumentos de políticas públicas poderá contribuir significativamente para o cumprimento das metas fixadas pela PNMC e requer a criação de fundos de financiamentos voltados para esses mercados, viabilizando o aumento do número de projetos e suas contribuições para mitigar as mudanças climáticas, bem como a consolidação desses mercados no Brasil. Além disso, faz-se necessário que o governo estimule a iniciativa privada a investir em tecnologias ambientalmente seguras, viabilizando o aumento de energias renováveis para o país, que contribuam para a transição para uma economia de baixo carbono, além da criação de incentivos fiscais que motivem as empresas a desenvolverem os projetos de redução de emissão de GEE. Enfim, recomenda-se como novas investigações futuras a realização de pesquisa com o objetivo de verificar de que forma os créditos de carbono são comercializado no Brasil, identificando as características dos contratos fechados no mercado financeiro nacional, como também a realização de estudos de caso em projetos representativos do mercado de carbono voluntário no Brasil, visando confrontar os dados secundários obtidos via análise de dados com os dados primários obtidos através de pesquisa de campo.
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Silva, Danilo Lopes Costa e. « Filmes finos de carbono depositados por meio da técnica de magnetron sputtering usando cobalto, cobre e níquel como buffer-layers ». Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-27082015-090945/.
Texte intégralRésumé :
Neste trabalho, foram produzidos filmes finos de carbono pela técnica de magnetron sputtering usando substratos monocristalinos de alumina com plano-c orientado em (0001) e substratos de Si (111) e Si (100), empregando Co, Ni e Cu como filmes intermediários (buffer-layers). As deposições foram conduzidas em três etapas, sendo primeiramente realizadas com buffer-layers de cobalto em substratos de alumina, onde somente após a produção de grande número de amostras, foram então realizadas as deposições usando buffer-layer de cobre em substratos de Si. Em seguida foram realizadas as deposições com buffer-layers de níquel em substratos de alumina. A cristalinidade dos filmes de carbono foi avaliada por meio da técnica de espectroscopia Raman e complementarmente por difração de raios X (DRX). A caracterização morfológica dos filmes foi feita por meio da microscopia eletrônica de varredura (MEV E FEG-SEM) e microscopia eletrônica de transmissão de alta resolução (HRTEM). Picos de DRX referentes aos filmes de carbono foram observados apenas nos resultados das amostras com buffer-layers de cobalto e de níquel. A espectroscopia Raman mostrou que os filmes de carbono com maior grau de cristalinidade foram os produzidos com substratos de Si (111) e buffers de Cu, e com substratos de alumina com buffer-layers de Ni e Co, tendo este último uma amostra com o maior grau de cristalinidade de todas as produzidas no trabalho. Foi observado que o cobalto possui menor recobrimento sobre os substratos de alumina quando comparado ao níquel. Foram realizados testes de absorção de íons de Ce pelos filmes de carbono em duas amostras e foi observado que a absorção não ocorreu devido, provavelmente, ao baixo grau de cristalinidade dos filmes de carbono em ambas amostras.In this work, carbon thin films were produced by the magnetron sputtering technique using single crystal substrates of alumina c-plane (0001) and Si (111) and Si (100) substrates, employing Co, Ni and Cu as intermediate films (buffer-layers). The depositions were conducted in three stages, first with cobalt buffer-layers where only after the production of a large number of samples, the depositions using cooper buffer-layers were carried out on Si substrates. Then, depositions were performed with nickel buffer-layers using single-crystal alumina substrates. The crystallinity of the carbon films was evaluated by using the technique of Raman spectroscopy and, complementarily, by X-ray diffraction (XRD). The morphological characterization of the films was performed by scanning electron microscopy (SEM and FEG-SEM) and high-resolution transmission electron microscopy (HRTEM). The XRD peaks related to the carbon films were observed only in the results of the samples with cobalt and nickel buffer-layers. The Raman spectroscopy showed that the carbon films with the best degree of crystallinity were the ones produced with Si (111) substrates, for the Cu buffers, and sapphire substrates for the Ni and Co buffers, where the latter resulted in a sample with the best crystallinity of all the ones produced in this work. It was observed that the cobalt has low recovering over the alumina substrates when compared to the nickel. Sorption tests of Ce ions by the carbon films were conducted in two samples and it was observed that the sorption did not occur probably because of the low crystallinity of the carbon films in both samples.