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1
Shirolkar, Ajay. "A Nano-composite for Cardiovascular Tissue Engineering." Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10840053.
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Cardiovascular disease (CVD) is one of the largest epidemic in the world causing 800,000 annual deaths in the U.S alone and 15 million deaths worldwide. After a myocardial infarction, commonly known as a heart attack, the cells around the infarct area get deprived of oxygen and die resulting in scar tissue formation and subsequent arrhythmic beating of the heart. Due to the inability of cardiomyocytes to differentiate, the chances of recurrence of an infarction are tremendous. Research has shown that recurrence lead to death within 2 years in 10% of the cases and within 10 years in 50% of the cases. Therefore, an external structure is needed to support cardiomyocyte growth and bring the heart back to proper functioning. Current research shows that composite materials coupled with nanotechnology, a material where one of its dimension is less than or equal to 100nm, has very high potential in becoming a successful alternative treatment for end stage heart failure. The main goal of this research is to develop a composite material that will act as a scaffold to help externally cultured cardiomyocytes grow in the infarct area of the heart. The composite will consist of a poly-lactic co glycolic acid (PLGA) matrix, reinforced with carbon nanotubes. Prior research has been conducted with this same composite, however the significance of the composite developed in this research is that the nanotubes will be aligned with the help of an electro-magnetic field. This alignment is proposed to promote mechanical strength and significantly enhance proliferation and adhesion of the cardiomyocytes.
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MacGibbon, Rebecca Mary Alice. "Designer nano-composite materials with tailored adsorption and sensor properties." Thesis, University of Surrey, 2006. http://epubs.surrey.ac.uk/844469/.
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This thesis is concerned with the possibility of producing novel materials by the sol-gel method that could be incorporated into a new sensing system to be used for the detection of hydrocarbons, in particular methane. Possibilities for a new system include coating optical fibres, at pre-determined points, with a material that causes some sort of disruption in the signal of the fibre when in contact with a hydrocarbon or specifically methane. Dip coating an optical fibre with a sol-gel would be a method for producing an optical fibre based system. This would provide variable chemistry, refractive index and hydrocarbon sensitivity. New silica-based sol-gel materials are presented and titania is incorporated to some of these materials in order to improve the catalytic potential of the system and to increase the refractive index. In order to increase the hydrophobicity and elasticity of the final coatings, organic modifiers are added. The sol-gel materials are characterised by a variety of techniques as both monoliths and thin films. Along with the characterisation, the samples are analysed to determine their potential to adsorb methane and water and the possibility of incorporating the samples in to an optical fibre sensor system utilising ultra-violet/visible spectroscopy. The presence of titania and/or organic modifiers in a silica based sol-gel system are seen to increase significantly the extent of methane adsorption and decrease the extent of water sorption at 293-298 K. It appears that having both titania and organic modifier gives a bigger effect on adsorption than either one alone. The reasons for this are considered in detail.
3
Peng, Suili. "Nano/micro particle-based functional composites and applications /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?NSNT%202007%20PENG.
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Peters, Sarah June. "Fracture Toughness Investigations of Micro and Nano Cellulose Fiber Reinforced Ultra High Performance Concrete." Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/PetersSJ2009.pdf.
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Zhai, Yun. "Studies on Structure and Property of Polymer-based Nano-composite Materials." ScholarWorks@UNO, 2013. http://scholarworks.uno.edu/td/1680.
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The mixing of polymers and nanoparticles makes it possible to give advantageous macroscopic material performance by tailoring the microstructure of composites. In this thesis, five combinations of nano inclusion and polymer matrix have been investigated.
The first type of composites is titanium dioxide/ polyaniline combination. The effects of 4 different doping-acids on the microstructure, morphology, thermal stability and thermoelectric properties were discussed, showing that the sample with HCl and sulfosalicylic dual acids gave a better thermoelectric property. The second combination is titanium dioxide/polystyrene composite. Avrami equation was used to investigate the crystallization process. The best fit of the mass derivative dependence on temperature has been obtained using the double Gaussian dependence. The third combination is titanium dioxide/polyaniline/ polystyrene. In the titanium dioxide/polyaniline/ polystyrene ternary system, polystyrene provides the mechanical strength supporting the whole structure; TiO2 nanoparticles are the thermoelectric component; Polyaniline (PANI) gives the additional boost to the electrical conductivity. We also did some investigations on Polyethylene odide-TiO2 composite. The cubic anatase TiO2 with an average size of 13nm was mixed with Polyethylene-oxide using Nano Debee equipment from BEE international;
Single wall carbon nanotubes were introduced into the vinyl acetate-ethylene copolymer (VAE) to form a connecting network, using high pressure homogenizer (HPH). The processing time has been reduced to 1/60 of sonication for HPH to give better sample quality. Theoretical percolation was derived according to the excluded volume theory in the expression of the threshold as a function of aspect ratio.
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Liu, Liyu. "Design and fabrication of microfluidic/microelectronic devices from nano particle based composites /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?NSNT%202008%20LIU.
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Johnson, Timothy Michael. "Strain Monitoring of Carbon Fiber Composite with Embedded Nickel Nano-Composite Strain Gage." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2622.
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Carbon fiber reinforced plastic (CFRP) composites have extensive value in the aerospace, defense, sporting goods, and high performance automobile industries. These composites have huge benefits including high strength to weight ratios and the ability to tailor their properties. A significant issue with carbon fiber composites is the potential for catastrophic fatigue failure. To better understand this fatigue, there is first a huge push to measure strain accurately and in-situ to monitor carbon fiber composites. In this paper, piezoresistive nickel nanostrand (NiNs) nanocomposites were embedded in between layers of carbon fiber composite for real time, in situ strain monitoring. Several different embedding methods have been investigated. These include the direct embedding of a patch of dry NiNs and the embedding of NiNs-polymer matrix nanocomposite patches which are insulated from the surrounding carbon fiber. Also, two different polymer matrix materials were used in the nanocomposite to compare the piezoresistive signal. These nanocomposites are shown to display repeatable piezoresistivity, thus becoming a strain sensor capable of accurately measuring strain real time and in-situ. This patch has compatible mechanical properties to existing advanced composites and shows good resolution to small strain. This method of strain sensing in carbon fiber composites is more easily implemented and used than other strain measurement methods including fiber Bragg grating and acoustic emissions. To show that these embedded strain gages can be used in a variety of carbon fiber components, two different applications were also pursued.
8
Song, Yicheng. "The behavior and properties of ferroelectric single crystals and ferroelectric nano-composites." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B3955806X.
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Song, Yicheng, and 宋亦誠. "The behavior and properties of ferroelectric single crystals and ferroelectric nano-composites." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B3955806X.
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Suberu, Bolaji A. "Multi-scale Composite Materials with Increased Design Limits." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377868507.
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Ball, Jeffrey Craig. "Design and analysis of multifunctional composite structures for nano-satellites." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2572.
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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017.The aim of this thesis is to investigate the applications of multifunctional compos- ite (MFC) technology to nano-satellite structures and to produce a working concept design, which can be implemented on future Cube-Satellites (CubeSats). MFC tech- nologies can be used to optimise the performance of the satellite structure in terms of mass, volume and the protection it provides. The optimisation of the structure will allow further room for other sub-systems to be expanded and greater payload allowance. An extensive literature view of existing applications of MFC materials has been conducted, along with the analysis of a MFC CubeSat structural design account- ing for the environmental conditions in space and well-known design practices used in the space industry. Numerical analysis data has been supported by empirical analysis that was done where possible on the concept material and structure. The ndings indicate that the MFC technology shows an improvement over the conventional alu- minium structures that are currently being used. Improvements in rigidity, mass and internal volume were observed. Additional functions that the MFC structure o ers include electrical circuitry and connections through the material itself, as well as an increase electromagnetic shielding capability through the use of carbon- bre composite materials. Empirical data collected on the MFC samples also show good support for the numerical analysis results. The main conclusion to be drawn from this work is that multifunctional composite materials can indeed be used for nano-satellite structures and in the same light, can be tailor-made to the speci c mission requirements of the satellite. The technology is in its infancy still and has vast room for improvement and technological development beyond this work and well into the future. Further improvements and additional functions can be added through the inclusion of various other materials.
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Henriques, Alexandra J. "Nano-Confined Metal Oxide in Carbon Nanotube Composite Electrodes for Lithium Ion Batteries." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3169.
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Lithium ion batteries (LIB) are one of the most commercially significant secondary batteries, but in order to continue improving the devices that rely on this form of energy storage, it is necessary to optimize their components. One common problem with anode materials that hinders their performance is volumetric expansion during cycling. One of the methods studied to resolve this issue is the confinement of metal oxides with the interest of improving the longevity of their performance with cycling. Confinement of metal oxide nanoparticles within carbon nanotubes has shown to improve the performance of these anode materials versus unconfined metal oxides. Here, electrostatic spray deposition (ESD) is used to create thin films of nano-confined tin oxide/CNT composite as the active anode material for subsequent property testing of assembled LIBs. This thesis gives the details of the techniques used to produce the desired anode materials and their electrochemical characterization as LIB anodes.
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Bai, Jing. "Percolation study of nano-composite conductivity using Monte Carlo simulation." Orlando, Fla. : University of Central Florida, 2009. http://purl.fcla.edu/fcla/etd/CFE0002644.
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Huang, Yaoting. "Fundamental studies on nano-composite phase change materials (PCM) for cold storage applications." Thesis, University of Birmingham, 2019. http://etheses.bham.ac.uk//id/eprint/8844/.
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This thesis studies the thermophysical properties and the phase change behaviour of EG-water and Salt-water based PCMs for cold storage applications, and investigates the role of adding MCNT on the thermophysical properties and the phase change processes. First, the structure of MCNT clusters is linked to the rheological behaviour of the nanofluids by fitting the experimental viscosity data to the modified K-D model. Second, the MCNT cluster information is used to predict thermal conductivity. The effective thermal conductivity of nanofluids not only relies on the particle concentration, but also depends on the particle cluster structure. The specific heat of MCNT nanofluids is decreasing proportionally with the concentration of MCNT. The supercooling degree of EG-water and salt-water based samples can be reduced by adding MCNT particles. The crystallization process of salt-water basefluid and nanofluid was observed and recorded under an optical microscope with cooling stage. Adding MCNT can promote the crystal growth rate.
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Giani, Niccolò <1994>. "Production and characterization of novel thermoplastic (nano)composite materials for additive manufacturing applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10421/1/Giani_Niccol%C3%B2_tesi.pdf.
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The increasing environmental global regulations have directed scientific research towards more
sustainable materials, even in the field of composite materials for additive manufacturing. In this
context, the presented research is devoted to the development of thermoplastic composites for FDM
application with a low environmental impact, focusing on the possibility to use wastes from different
industrial processes as filler for the production of composite filaments for FDM 3D printing. In
particular carbon fibers recycled by pyro-gasification process of CFRP scraps were used as
reinforcing agent for PLA, a biobased polymeric matrix. Since the high value of CFs, the ability to
re-use recycled CFs, replacing virgin ones, seems to be a promising option in terms of sustainability
and circular economy. Moreover, wastes from different agricultural industries, i.e. wheat and rice
production processes, were valorised and used as biofillers for the production of PLA-biocomposites.
The integration of these agricultural wastes into PLA bioplastic allowed to obtain biocomposites with
improved eco-sustainability, biodegradability, lightweight, and lower cost. Finally, the study of novel
composites for FDM was extended towards elastomeric nanocomposite materials, in particular TPU
reinforced with graphene. The research procedure of all projects involves the optimization of
production methods of composite filaments with a particular attention on the possible degradation of
polymeric matrices. Then, main thermal properties of 3D printed object are evaluated by TGA, DSC
characterization. Additionally, specific heat capacity (CP) and Coefficient of Linear Thermal
Expansion (CLTE) measurements are useful to estimate the attitude of composites for the prevention
of typical FDM issues, i.e. shrinkage and warping. Finally, the mechanical properties of 3D printed
composites and their anisotropy are investigated by tensile test using distinct kinds of specimens with
different printing angles with respect to the testing direction.
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Moro, Marjan. "Nano-Characterization of Ceramic-Metallic Interpenetrating Phase Composite Material using Electron Crystallography." Youngstown State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1340223324.
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KORICHO, ERMIAS GEBREKIDAN. "Implementation of Composites and Plastics Materials for Vehicle Lightweight." Doctoral thesis, Politecnico di Torino, 2012. http://hdl.handle.net/11583/2497432.
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Due to ever more severe environmental regulations, safety standards and rise of fuel cost, design of lightweight vehicle is becoming a challenging task in automotive industry. For these reasons, multidisciplinary design approaches are becoming mandatory that takes into account all parties’ interests.
The thesis addresses the potential use of composites, nanomodified composites, thermoplastic and smart hot melts adhesives materials in selected automotive applications to achieve lightweight vehicle. Special attention was paid to specific parts of vehicle structures that are directly related to occupant and pedestrian safety concerns such as B-pillar, frontal bumper subsystem, and engine subframe.
Two approaches were implemented to design composites and thermoplastic intensive vehicle components: experimental test and numerical simulation approaches. In experimental approach, experimental method was developed to establish reliable test procedure to characterize composite materials. Then, selected materials were manufactured and characterized under quasi-static and dynamic loading conditions. Furthermore, selected nano-modified composite materials were characterized to understand effect of presence of nano-clays into the matrix on the mechanical behavior of base material. On the other hand, thermoplastic material was modified with short glass fibers to improve its mechanical behavior for frontal vehicle system application. Besides, in this thesis adhesive joint was considered as alternative solution to achieve vehicle lightweight targets. Detailed material characterization and parametric study of hot melt adhesive (HMA) single lap joint were performed for bumper subsystem application. Accelerated ageing were also performed on selected HMA to represent the worst environmental condition in which the bumper subsystem could be exposed. Also, selected hot-melt adhesive was modified by nano-metal particles to obtain smart adhesive that allows bonded vehicle components to be easily detached during disassembly process.
Particularly, simplified form of composite B-pillar (T-joint) was manufactured and quasi- static experimental tests were performed to validate the results obtained from numerical simulations.
In numerical approach, composite and thermoplastic vehicle components were modeled, they are presented in chapters from seven to nine. Commercially available software have been used for these simulations. Structural analysis and optimizations were performed to obtain a competitive performance in terms of strength, stiffness and crash worthiness against conventional material solutions.
The results found from experimental and numerical simulation works revealed that composites and thermoplastics materials can deliver better performances under static and crashing load conditions. Using those materials, considerable amount of vehicle weight reduction was also achieved by keeping the desired design performance criteria. It is also worth to underline that manufacturing process and joining techniques are some of the main factors that should be taken into consideration during design of composite and thermoplastic components for vehicle applications.
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Khfagi, Osama Mohamed Ibrahim. "Synthesis of Co-Cr-Mo/ fluorapatie nano-composite coating by pulsed laser depositionfor dental applications." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2259.
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Thesis (MTech (Biomedical Technology))--Cape Peninsula University of Technology, 2016.Metallic materials play an essential role in assisting with the repair or replacement of bone tissue that has become diseased or damaged. Metals are more suitable for load bearing applications compared to ceramics or polymeric materials due to high mechanical strength and fracture toughness that are exhibited by metallic materials. However, the main limitation in the application of these metallic materials is the release of the toxic metallic ions. The release of these ions is caused by the interaction of metallic materials with human body fluids. These ions react with body tissue, which might lead to various adverse tissue reactions and/or hypersensitivity reactions. Cobalt-chromium-molybdenum (Co-Cr-Mo) alloys are one of the most useful alloys for biomedical applications such as dental and orthopedic implants because of acceptable mechanical properties and biocompatibility. However, the use of these alloys in biomedical applications has of late come under scrutiny recently due to unacceptable revision rates of applications such as hip resurfacing and total hip arthroplasty designs. Failure analysis has demonstrated that solid and soluble wear debris and corrosion products resulted. This release of ions from the joints has resulted in adverse local tissue reactions. Laser-aided deposition is a material additive based manufacturing process via metallurgically bonding the deposited material to the substrate. Due to its capability to bond various materials together, it became an attractive technology. The principal aims of this study were to 1a) fabricate nanocomposite materials by depositing fluorapatite nanopowder onto the Co-Cr-Mo dental alloy using pulsed laser deposition and 1b) evaluate which laser beam energy and layer thickness, based on the exposure time period, would be applicable, and 2) evaluate bioactivity properties on biological material.
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Khan, Abdul Samad. "A novel bioactive nano-composite : synthesis and characterisation with potential use as dental restorative material." Thesis, Queen Mary, University of London, 2009. http://qmro.qmul.ac.uk/xmlui/handle/123456789/441.
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It is desirable for a dental restorative material to have bioactive and bonding properties. This study focuses on the synthesis of a covalently-linked polyurethane/nanohydroxyapatite (PU/nHA) composite and evaluates its chemical, physical, thermal and biochemical characteristics. nHA powder was produced from the sol-gel and novel composite material was chemically prepared by utilising solvent polymerisation. The resulting composites were analysed by chemical, thermal, and mechanical characterisations and electrospun to form fibre mats. The composites were hydrolytically degraded in deionised water and phosphate buffer solution (PBS) and were analysed. Bioactive behaviour was determined in modified-simulated body fluid. The bioadhesion with dentine was analysed in distilled water and artificial saliva. Cell growth and proliferation was measured and number of adhering bacteria was determined and serial dilution followed by plating for colony forming units per disc. Spectral analyses showed the grafted isocyanate and ether peaks on nHA indicating that urethane linkage was established. Covalent-linkage between nHA and PU were found in this novel composite with no silane agent. The physical and thermal properties were enhanced by nHA. These composites had high resistance toward hydrolysis and little degradation was observed. Bioadhesion and bioactivity analysis showed the composite adhered firmly on the tooth surface (dentine) and bond strength was similar to existing obturating material. Higher nHA content composite showed a thicker layer of adhesion. Cells were proliferated although at a lower rate of growth compared to PU, whereas, there was reduction in bacteria adhering to the grafted composite compared to PU. With its low bacterial adhesion and biocompatibility it may provide a promising solution to reduce infections. The electrospun nano-fibres were successfully developed and revealed no loose nHA particles. Hence, this novel composite has the potential to be used as a bioactive dental restorative material.
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Nyamsi, Francois T. "Carbon Nanotube and Soft Magnetic Lightweight Materials in Electric Machines." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535381574629281.
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Mokhtari, Morgane. "FeCr composites : from metal/metal to metal/polymer via micro/nano metallic foam, exploitation of liquid metal dealloying process." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI088/document.
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Les métaux micro ou nanoporeux sont très attrayants notamment pour leur grande surface spécifique. Le désalliage dans un bain de métal liquide permet une dissolution sélective d'une espèce chimique (l'élément soluble) à partir d'un alliage d'origine (le précurseur) composé de l'élément soluble et d'un élément cible (qui deviendra nano/micro poreux) non soluble dans le bain de métal liquide. Quand le précurseur est plongé dans le bain de métal liquide, à son contact, l'élément soluble va se dissoudre dans le bain tandis que l'élément cible va en parallèle se réorganiser spontanément afin de former une structure poreuse. Quand l'échantillon est retiré du bain, il est sous la forme d'une structure bi-continue composée de deux phases : l'une étant la structure poreuse composée de l'élément cible et l'autre est une phase dans laquelle est présente l'élément du bain avec l'élément sacrificiel en solution solide. Cette phase peut être dissoute par une attaque chimique afin d’obtenir le métal nano/micro poreux. Les objectifs principaux de cette thèse sont l'élaboration et la caractérisation microstructurale et mécanique de 3 différents types de matériaux par désalliage dans un bain de métal liquide : des composites métal-métal (FeCr-Mg), des métaux poreux (FeCr) et des composites métal-polymère (FeCr-matrice époxy). Le dernier objectif est l'évaluation des possibilités d'utiliser la technique de désalliage dans un bain de métal liquide dans un contexte industriel. L'étude de la microstructure est basée sur des observations 3D faites par tomographie aux rayons X et des analyses 2D réalisées en microscopie électronique (SEM, EDX, EBSD). Pour mieux comprendre le désalliage, le procédé a été suivi in situ en tomographie aux rayons X et diffraction. Enfin, les propriétés mécaniques ont été évaluées par nanoindentation et compressionNanoporous metals have attracted considerable attention for their excellent functional properties. The first developed technique used to prepare such nanoporous noble metals is dealloying in aqueous solution. Porous structures with less noble metals such as Ti or Fe are highly desired for various applications including energy-harvesting devices. The less noble metals, unstable in aqueous solution, are oxidized immediately when they contact water at a given potential so aqueous dealloying is only possible for noble metals. To overcome this limitation, a new dealloying method using a metallic melt instead of aqueous solution was developed. Liquid metal dealloying is a selective dissolution phenomenon of a mono-phase alloy solid precursor: one component (referred as soluble component) being soluble in the metallic melt while the other (referred as targeted component) is not. When the solid precursor contacts the metallic melt, only atoms of the soluble component dissolve into the melt inducing a spontaneously organized bi-continuous structure (targeted+sacrificial phases), at a microstructure level. This sacrificial phase can finally be removed by chemical etching to obtain the final nanoporous materials. Because this is a water-free process, it has enabled the preparation of nanoporous structures in less noble metals such as Ti, Si, Fe, Nb, Co and Cr. The objectives of this study are the fabrication and the microstructure and mechanical characterization of 3 different types of materials by dealloying process : (i) metal/metal composites (FeCr-Mg), (ii) porous metal (FeCr) (iii) metal/polymer composites (FeCr-epoxy resin). The last objective is the evaluation of the possibilities to apply liquid metal dealloying in an industrial context. The microstructure study was based on 3D observation by X-ray tomography and 2D analysis with electron microscopy (SEM, SEM-EDX, SEM-EBSD). To have a better understanding of the dealloying, the process was followed in situ by X-ray tomography and X-ray diffraction. Finally the mechanical properties were evaluated by nanoindentation and compression
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Fraser, Andrew. "Mesoscale behavior of an aluminum-manganese dioxide-epoxy mixture under shock loading: from milli to nano-sized aluminum particles." [Milwaukee, Wis.] : e-Publications@Marquette, 2009. http://epublications.marquette.edu/theses_open/7.
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Atbayga, Abdalla Mohammed Ali. "In vitro anti-bacterial activity of titanium oxide nano-composites containing benzalkonium chloride and chlorhexidine gluconate." Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/1460.
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Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Biomedical Technology
In the Faculty of Health and Wellness Sciences
At Cape Peninsula University of Technology
2013Newly developed and commercial dental resins which are commonly used nowadays have to be tested for their antimicrobial susceptibility. The purpose of this in vitro study was to investigate the antimicrobial activity of a titanium oxide (TiO2) nano-composite which was prepared with different antibacterial substances and used as restoratives in dentistry to combat certain selected bacteria that are considered the principle causes of some tooth diseases, for example, tooth decay and to prevent unsuccessful dental restoration. The TiO2 nano-composite was prepared and divided into four groups: The first group was an untreated TiO2 nano-composite. The second group was silane-treated TiO2 nano-composite. The third group was treated TiO2 nano-composite which was combined with chlorhexidine gluconate (CHxG). The fourth group was treated TiO2 nano-composite which was combined with benzalkonium chloride (BzCl). Five of the selected bacteria were grown overnight in Petri dishes. Four of them, namely, Escherichia coli (E. coli) ATCC 11775, Staphylococcus aureus (S. aureus) ATCC 12600, Enterococcus faecalis (E. faecalis) ATCC 29212, and Pseudomonas aeruginosa (P. aeruginosa) ATCC 10145, were grown on Müller-Hinton Agar (MHA). Streptococcus mutans (S. mutans) ATCC 25175 was grown on Brain Heart Infusion (BHI) agar. All these bacteria were tested against the TiO2 nano-composite, and incubated for 24 hours at 37°C, except S. mutans, which was incubated separately and exposed to CO2. It was placed into a CO2 water-jacketed incubator in an atmosphere of 5% CO2 for 24 hours at 37°C. The obtained results showed that neither of the groups of TiO2 nano-composites, (untreated TiO2 nano-composite and treated TiO2 nano-composite) exhibited antimicrobial activity against the pathogens. Only preparations of TiO2 nano-composites at a concentration of 3 %m/m of both CHxG and BzCl showed antimicrobial activity against S. aureus. Antimicrobial activity against S. mutans, E. coli, P. aeruginosa, E. faecalis and S. aureus, were only realized at a concentration of 10 %m/m for both CHxG and BzCl..
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Greco, Pier Paolo. "Development of novel polymeric and composite nano-structured micro-porous materials for impact resistance applications." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2517.
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Impact resistant materials (IRMs) are widely used in the automotive and packaging industry. Their main purpose is the protection of the transported occupants or goods. Cellular materials as well as structures combine lightness with large deformation under load. The energy absorption mechanism is provided by limiting the peak load and ensuring the elastic deformation of the IRMs. Polymeric foams are largely used as IRMs due to their cellular structure. Prediction of the foam properties in terms of Young’s Modulus (Elastic Modulus) and the onset of Plateau Region can be related to the foam density and the mechanical properties of the bulk material (Gibson and Ashby model). The structure of the foam is only partly accounted for in the Gibson and Ashby model in terms of material density. However, it is possible to produce cellular materials with the same density but very different internal architectures. This cannot easily be exploited in conventional polymer foams but the processing of High Internal Phase Emulsion (PolyHIPE) and its polymerisation route to produce PolyHIPE Polymers (PHPs) can produce materials with very different structures. Experiments have revealed that the PHPs properties are dictated by their detailed structure. Elastic PHPs with: 1) varying ratio of polymerizable oil phase with respect to aqueous phase and 2) varying mixing time/energy input were produced and tested by mechanical compression at different temperatures and strain rates. The elastic modulus increases with a quadratic law as a function of the polymerizable oil phase content of the HIPE when the mixing time is the same, as predicted by the model. The Specific Absorption Energy (SAE), represented by the area under the stress-strain curve, increases in a similar way. Increasing mixing time on HIPE has the effect of modifying the cellular structure. Smaller pores and narrower distribution of pores are observed. Such features are consistent for any set of PHPs densities and represent a design tool when some specific mechanical characteristics are prescribed. The assessment of process-structure-properties relationships was performed by combining the mechanical response of the various PHPs with the imaging of their structure by Scanning Electron Microscopy. The properties of PHPs were benchmarked with reference to two commercially available products. One material is characterised by a porous structure with a relatively high Young’s Modulus while the other by a non-porous and composite-like solid structure with lower elastic modulus. The properties of the PHPs can be engineered to shift from a foam-like material to a composite-like through the processing parameters which in turn modify the material porous structure. The temperature has very limited effect on the PHPs material unlike for the reference commercial materials. The enhancement of properties (increasing Elastic Modulus and SAE) induced by changing the processing route are remarkable for such a class of porous materials. When plotted on a Modulus-Density chart, the PHPs fill an existing material-chart gap, representing a new class of materials and opening new possibilities as IRMs.
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Vatani, Morteza. "Additive Manufacturing of Stretchable Tactile Sensors: Processes, Materials, and Applications." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1436202948.
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Ayanda, Olushola Sunday. "Adsorption of organotin compounds on nano metal oxide/silica, activated carbon and fly ash composite materials." Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/760.
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Thesis submitted in fulfilment of the requirements for the degree
Doctor of Technology: Chemistry
in the Faculty of Applied Sciences
at the Cape Peninsula University of Technology
2013In this present study, the physicochemical properties, nature and morphology of prepared composite materials involving activated carbon, fly ash, nFe3O4, nSiO2 and nZnO in the 1:1 ratio for two components composite materials and 1:1:1 for three components composite materials were investigated. The nature, morphology and elemental characterizations of these materials were carried out by means of modern analytical methods such as scanning electron and transmission electron microscopy (SEM and TEM), x-ray diffraction (XRD), x-ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled plasma atomic emission spectroscopy (ICP-AES) and Fourier transform infrared spectroscopy (FTIR). Other physicochemical characterizations undertaken were CNH analysis, ash content, pH, point of zero charge and surface area and porosity determination by Brunauer, Emmett and Teller (BET). The precursors and composite materials were then applied to the sorption (remediation) of tributyltin (TBT) and triphenyltin (TPT) from artificial seawater and wastewater and the adsorption efficiencies for the precursors and the composites compared. The adsorption of TBT and TPT onto these materials as a function of adsorbent amount, contact time, pH, stirring speed, initial adsorbate concentration and temperature was investigated. Maximum organotin adsorption was recorded within the pH range of normal saline water (pH 8). Approximately 99.95 %, 95.75 %, 96.78 %, 99.88 %, 96.96 %, 99.98 %, 99.99 %, 99.99 % and 99.99 % TBT were removed from 25 mL of 100 mg/L TBT-contaminated artificial seawater using 0.5 g adsorbents at a contact time of 60 min, pH 8, stirring speed 200 rpm and temperature of 80 oC by activated carbon, fly ash, nFe3O4, nSiO2, nZnO, fly ash/activated carbon, nFe3O4/activated carbon, nSiO2/activated carbon and nZnO/activated carbon composite, respectively and the adsorption of TBT onto these adsorbents was endothermic. Approx. 99.99 %, 96.54 %, 95.50 %, 96.92 %, 97.14 %, 99.99 %, 98.44 %, 98.98 % and 99.66 % TPT were also removed from 25 mL of 100 mg/L TPT-contaminated artificial seawater using 0.5 g adsorbents at a contact time of 60 min, pH 8, stirring speed 200 rpm and a temperature of 20 oC by the activated carbon, fly ash, nFe3O4, nSiO2, nZnO, fly ash/activated carbon, nFe3O4/fly ash, nSiO2/fly ash and nZnO/fly ash composite, respectively. The adsorption of TPT onto activated carbon and fly ash/activated carbon composite from TPT – contaminated artificial seawater was endothermic while TPT adsorption onto fly ash, nFe3O4, nSiO2, nZnO, nFe3O4/fly ash, nSiO2/fly ash and nZnO/fly ash composites from TPT – contaminated artificial seawater was exothermic. The adsorption of TBT and TPT onto nFe3O4/fly ash/activated carbon and nSiO2/fly ash/activated carbon composites from TBT – and TPT – contaminated water, respectively were endothermic and approx. 99.98 % and 99.99 % of TBT and TPT, respectively were removed from the initial concentration of 100 mg/L OTC by the composites at a temperature of 80 oC, 60 min contact time, pH 8 and a stirring speed of 200 rpm. The adsorption kinetics of all the precursors and composite materials fitted well with the pseudo second-order kinetic model while the adsorption isotherm data could be well described by the Freundlich isotherm model except TBT adsorption onto nZnO/activated carbon and nFe3O4/activated carbon composite from TBT contaminated artificial seawater, TPT adsorption onto activated carbon and fly ash/activated carbon from TPT contaminated artificial seawater, and TPT sorption onto nSiO2/fly ash/activated carbon composite from TPT – contaminated water which could be described by both the Freundlich and Dubinin-Radushkevich (D-R) isotherm models. Optimal conditions for the adsorption of TBT and TPT from artificial seawater were further applied to TBT and TPT removal from TBT – and TPT – contaminated natural seawater obtained from Cape Town harbour and the results obtained show that 99.71 %, 79.23 %, 80.11 %, 82.86 %, 80.42 %, 99.75 %, 99.88 %, 99.83 % and 99.88 % TBT were removed from TBT – contaminated natural seawater by activated carbon, fly ash, nFe3O4, nSiO2, nZnO, fly ash/activated carbon, nFe3O4/activated carbon, nSiO2/activated carbon and nZnO/activated carbon composite, respectively while 99.90 %, 96.44 %, 95.37 %, 96.75 %, 97.03 %, 99.92 %, 98.42 %, 98.92 % and 99.58 % TPT were removed from TPT – contaminated natural seawater by activated carbon, fly ash, nFe3O4, nSiO2, nZnO, fly ash/activated carbon, nFe3O4/fly ash, nSiO2/fly ash and nZnO/fly ash composite, respectively. Experimental results therefore show that the composite materials present higher organotin adsorption efficiency than the precursors due to the nature and improved properties of the composite materials and can therefore be utilized for the remediation of organotin contamination from industrial and/or shipyards process wastewater to > 99 % reduction before discharge into the environment.
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Jordan, Jeff. "Composites at micro- and nano-scale and a new approach to the problem of a concentrated force on a half-plane." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/16431.
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Nauyoks, Stephen Edwin. "Microstructure of nano and micron size diamond-SIC composites sintered under high pressure high temperature conditions." [Fort Worth, Tex.] : Texas Christian University, 2009. http://etd.tcu.edu/etdfiles/available/etd-10152009-102152/unrestricted/Nauyoks.pdf.
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Mahadevegowda, Amoghavarsha. "Processing, microstructure and properties of polymer-based nano-composite dielectrics for capacitor applications." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:fb974b13-2ec5-4104-9f80-45d1cb97eb48.
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The processing and properties of novel polymer-based nano-composite (PNC) dielectrics for capacitor applications has been studied. PNCs were fabricated via a vacuum based deposition technique and their micro/nano-structure, chemical and dielectric properties investigated. After process development and optimisation, co-deposited Al and nylon-6 PNCs had a dielectric constant k∼7 at an approximate Al volume fraction of 0.3 that agreed with analytical predictions if it was assumed that the Al transformed to an oxide in-situ and/or after deposition. The significant effect of absorbed water vapour and temperature on PNC dielectric properties was revealed using different types of post-deposition heat treatment. Alternately-deposited PNCs consisting of Al or Ag 2-20 nm layers sandwiched between nylon-6 layers were fabricated in which the overall PNC Al or Ag volume fraction was controlled by varying the nominal Al or Ag layer thickness. Ag layers comprised of discrete nano-islands that produced a nano-capacitor network effect that increased k to ∼11. In the case of Al layers, when the layer thickness was ≥ 5 nm, corresponding to a nominal volume fraction of 0.1, Al (core)-oxide (shell) nanoparticles were formed and the PNC dielectric constant increased to ∼19. The detailed nano-structure of the core-shell particles was studied using various types of transmission electron microscopy (TEM), and the elevations in dielectric constant ascribed to multiple-interface polarisation effects dependent on the formation of the core-shell structure. PNCs based on alternate deposition of Ti sandwiched in nylon-6, and then both Ti and Ag in nylon-6 were also fabricated, with k reaching ∼73 for Ag+Ti/nylon-6 PNCs. As well as Ti-based core (metal)-shell (oxide) particles, the Ag volume fraction was sufficiently high in the 10 nm nylon-6 layers to again form a nano-capacitor network that contributed to the overall device capacitance and effective dielectric constant. Again, various types of high magnification TEM were critical in resolving the Ti-based core-shell structure and its role in high-k behaviour. The vacuum-based alternate deposition technique has been developed to offer ease of operation, reliability, flexibility and applicability to chemically different filler and matrix systems in the fabrication of high-k PNC based capacitors, in which high-k performance relies critically on the formation of core (metal)-shell (oxide) particles in both Al and Ti based systems.
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Cheekati, Sree Lakshmi. "GRAPHENE BASED ANODE MATERIALS FOR LITHIUM-ION BATTERIES." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1302573691.
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Holliday, Nathan. "Processing and Properties of SBR-PU Bilayer and Blend Composite Films Reinforced with Multilayered Nano-Graphene Sheets." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1458300045.
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Ljiljana, Tanasić. "Višeskalna strategija strukturiranja polimernih nano-kompozita na osnovu različitih prekursora." Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2011. https://www.cris.uns.ac.rs/record.jsf?recordId=77483&source=NDLTD&language=en.
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Ovaj rad je imao za cilj , razvoj postupka sinteze polimernih prekursora mreža na baziobnovljivih sirovina. Razvijen je postupak sinteze poli laktida u rastvoru dihlor metana. Vreme trajanja postupka sinteze je 6 h, a uspešnost samog procesa je potvrđena metodama identifikacije i karakterizacije dobijenih polimera PLLA. U ovom radu, za ispitivanja dobijenih polimernih materijala, uzimajući u obzir ideju o krajnjoj nameni, korišćene su sledeće metode: GPC ( Gel Permeation Chromarography) za određivanje raspodele molekulske mase; IR spektrofotometrija, prikazuje vibraciju atomskih, molekulskih ili funkcionaknih grupa; i termička analiza TGA i DSC, za praćenje promena pri kontrolisanom zagrevanju i hlađenju.Jedan od ciljeva rada je bio i da se da pregled postojećih teorija ojačanja elastomera punilima sa nano česticama, i ispita ponašanje nano-kompozitnih materiajala pod dejstvom visoko energetskog zračenja ( gama zračenja). U eksperimentalnom delu ispitivani su elastomerni materijale na bazi butadienakrilonitrilnog kaučuka (NBR) i hlorsulfonovanog polietilenskog kaučuka (CSM) . Mešanjem CSM i NBR formiraju se umreženi sistemi, koji se koriste kao prekursori mreža za dobijanje nano-kompozitnih materijala ojačanaih česticama aktivnih punilačađi i silicijum (IV) oksida. Kod tako dobijenih materijala ispitivane su karakteristike pre i posle ozračivanja γ zracima. Dinamičko-mehaničkom analizom potvrđen je ojačavajući efekat punila.This work was aimed at the development procedure for the synthesis of polymer precursors network based on renewable raw materials. Developed a procedure for synthesis of poly lactide in solution, dichloro methane. The duration of the synthesis procedure was 6 h, and the success of the process was confirmed by the methods of identification and characterization of the obtained polymer PLLA. In this paper, the investigation obtained polymer materials, taking into account the idea of final destination, following methods were used: GPC (gel permeation Chromarography) to determine the distribution of molecular weight, IR spectrophotometry, showing the vibration of atomic, molecular or funkcionaknih group, and thermal analysis TGA and DSC, to track changes in a controlled heating and cooling. One of the aims of this study was to be given to review of existing theories of reinforcement fillers elastomer with nano particles, and examine the behavior of nano-composite materiajala under the influence of high energy radiation (gamma radiation). In the experimental part of elastomeric materials have been studied on the basis of butadienakrilonitrilnog rubber (NBR) and chlorosulphonated polyethylene rubber (CSM). CSM NBR mixing and forming the network system, which are used as precursors for a network of nano-composite particles ojačanaih active fillers-carbon black and silicon (IV) oxide. With so obtained materials were investigated characteristics before and after irradiation with γ rays. Dynamic-mechanical analysis confirmed the reinforcing effect of fillers.
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Tilliander, Ulrika. "Synthesis of nano sized Cu and Cu-W alloy by hydrogen reduction." Licentiate thesis, KTH, Materials Science and Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-353.
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The major part of the present work, deals with the reduction kinetics of Cu2O powder and a Cu2O-WO3 powder mixture by hydrogen gas, studied by ThermoGravimetric Analysis (TGA). The reduction experiments were carried out both isothermally and non-isothermally on thin powder beds over different temperature intervals. During the experiments, the reductant gas flow rate was kept just above the starvation rate for the reaction to ensure that chemical reaction was the rate-controlling step. The activation energy for the reactions was evaluated from isothermal as well as non-isothermal reduction experiments.
In the case of the reduction of Cu2O, the impact of the stability of the copper oxide on the activation energy for hydrogen reduction under identical experimental conditions is discussed. A closer investigation of additions of Ni or NiO to Cu2O did not have a perceptible effect on the kinetics of reduction.
In the case of the reduction of the Cu2O-WO3 mixture, the reaction mechanism was found to be affected in the temperature range 923-973 K, which is attributed to the reaction/transformation in the starting oxide mixture. At lower temperatures, Cu2O was found to be preferentially reduced in the early stages, followed by the reduction of the tungsten oxide. At higher temperatures, the reduction kinetics was strongly affected by the formation of a complex oxide from the starting materials. It was found that the Cu2O-WO3 mixture underwent a reaction/transformation which could explain the observed kinetic behavior.
The composition and microstructures of both the starting material and the reaction products were analyzed by X-ray diffraction (XRD) as well as by microprobe analysis. vi Kinetic studies of reduction indicated that, the mechanism changes significantly at 923 K and the product formed had unusual properties. The structural studies performed by XRD indicated that, at 923 K, Cu dissolved in W forming a metastable solid solution, in amorphous/nanocrystalline state. The samples produced at higher as well as lower temperatures, on the other hand, showed the presence two phases, pure W and pure Cu. The SEM results were in conformity with the XRD analysis and confirmed the formation of W/Cu alloy. TEM analysis results confirmed the above observations and showed that the particle sizes was about 20 nm.
The structure of the W/Cu alloy produced in the present work was compared with those for pure copper produced from Cu2O produced by hydrogen reduction under similar conditions. It indicated that the presence of W hinders the coalescence of Cu particles and the alloy retains its nano-grain structure. The present results open up an interesting process route towards the production of intermetallic phases and composite materials under optimized conditions.
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Jafari, Abbas. "The Effect of Citric Acid on Amorphous Calcium Carbonate, Mesoporous Magnesium Carbonate and Calcium Magnesium Composite : A brief study." Thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-435989.
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During the past decades, emission of greenhouse gases has accelerated to unsustainable levels. This is a serious issue that can have a devastating impact on everything from global economy to the terrestrial or marine ecosystem. A method for reducing the emission is named carbon capture and storage, which this project is based on. In this study, different concentrations of citric acid (CA) is used (as an additive) for the enhancement and optimization of carbon dioxid sorption properties of amorphous calcium carbonate (ACC), mesoporous magnesium carbonate (MMC) and calcium magnesium carbonate composite (CMC). These materials were heat treated in a calcination and an alternating carbonation process in order to study the carbon dioxid sorption performance. During the calcination process, CA undergoes a pyrolysis reaction in order to increase the specific surface area of the individual nanoparticles, which is an important factor for the sorption capacity. In the case of CMC, different molar ratios of magnesium oxide and calcium oxide were used in order to alter the concentration of the resulting magnesium oxide prior to heating. All three materials consisted of aggregations of nanometer-sized particles. Thermogravimetric analysis, scanning electron microscopy, surface area and porosimetry and infrared spectroscopy analysis suggest that the carbon dioxid sorption properties and the sintering stability of ACC and MMC do not improve since CA evaporates due to pyrolysis. Sintering was a greater problem for the evaluated CA treated ACC sample. However, in the case of CMC, the sorption and sintering properties were enhanced due to the higher Tamman-temperature of magnesium oxide, specifically for the lower concentration of magnesium oxide. After 19 carbonation cycles, CMC-1:1-25% CA showed signs of improved sintering stability and sorption capacity, compared to ACC-75% CA.Presentationen genomfördes på distans.
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Gunawidjaja, Ray. "Organic/inorganic nanostructured materials towards synergistic mechanical and optical properties /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29733.
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Thesis (Ph.D)--Industrial and Systems Engineering, Georgia Institute of Technology, 2010.Committee Chair: Tsukruk, Vladimir; Committee Member: Bucknall, David; Committee Member: Kalaitzidou, Kyriaki; Committee Member: Shofner, Meisha; Committee Member: Tannenbaum, Rina. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Blivi, Adoté Sitou. "Effet de taille dans les polymères nano-renforcés : caractérisation multi-échelles et modélisation." Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2431/document.
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Le travail présenté dans ce document vise à mettre en évidence et à comprendre l'effet de la taille nanométrique des renforts sur les propriétés des nanocomposites avec une approche expérimentale. Des nanocomposites de PMMA et particules de silice (15nm, 25nm, 60nm, 150nm et 500nm) de fractions volumiques 2 0/0, 40/0 et 6 0/0 ont été fabriqués. Des analyses multi-échelles (MET et DRX-WAXS) ont montré que les paramètres caractéristiques de la microstructure des nanocomposites varient avec la taille des nanoparticules. En effet, la diminution de la taille des nanoparticules à fraction volumique constante a entrainé une diminution de la distance intermoléculaire. Cette diminution a induit une densification de la matrice et une réduction de la mobilité des chaînes de la matrice. Des essais mécaniques (traction, DMA) ont montré que les modules de Young (E) et de conservation (E') des nanocomposites augmentent avec la diminution de la taille des nanoparticules à fraction volumique constante. Et que l'augmentation de E' est conservée avec l'augmentation de la température. Une augmentation des températures de transition vitreuse (Tg) et de dégradation (Td) a également été observée avec les essais DSC, DMA et ATG. Le modèle de la borne inférieure d'Hashin-Shtrikman étendue aux nanocomposites à renforts sphériques proposé par Brisard a été utilisé. La modélisation des modules élastiques des nanocomposites a montré que pour reproduire les données expérimentales, il faut que d'une part que les modules surfaciques caractérisant l'interface soient dépendants de la taille des nanoparticules. Et d'autre part, tenir compte de l'état de dispersion des nanoparticulesThe work presented in this paper aims to highlight and to understand the size effect of nano-reinforcements on nanocomposite properties With an experimental approach. Nanocomposites of PMMA and silica particles With different sizes (15nm, 25nm, 60nm, 150nm and 500nm) and volume fractions (20/0, 4 0/0 and 60/0) were manufactured. Multiscale analysis (MET and DRX-WAXS) have shown that the characteristic parameters of the microstructure of nanocomposites vary With the size of the nanoparticles. Indeed, the decrease in the size of nanoparticles at a given volume fraction implies a decrease of the intermolecular distance. This decrease has induced a densification of the matrix and a decrease of the matrix chain mobility. Mechanical tests (tensile, DMA) have shown that the young (E) and the conservation (E') moduli of the nanocomposites increase With the decrease in the size of the nanoparticles With a constant volume fraction. And the increase of E l is kept when temperature growing. An increase in glass transition (Tg) and degradation temperature (Td) was also observed With the DSC, DMA and ATG tests. Experimental elastic properties of the nanocomposites were used to assess the relevance of size effect micromechanical models, particularly the Hashin-Shtrikman bounds With interface effects proposed by Brisard. The modeling has shown that to reproduce the experimental elastic moduli of nanocomposites, the elastic coefficients of the interface must be dependents on particle sizes. And the state of dispersion of particles must be taken into account
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Pallikonda, Mahesh Kumar Pallikonda. "FORMING A METAL MATRIX NANOCOMPOSITE (MMNC) WITH FULLY DISPERSED AND DEAGGLOMERATED MULTIWALLED CARBON NANOTUBES (MWCNTs)." Cleveland State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=csu1503937490966191.
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Shamshurov, A. V., V. M. Beresnev, and N. A. Volovicheva. "Nano-reinforced Quartz Composites." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35246.
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We have studied the process of interaction between the components in the system «β-SiO2–Fe3O4–Na2O» in the temperature range from 20 to 1100 °C. Nano-reinforced composite building materials were developed on the base of quartz raw material. Developed materials are produced by low-temperature cal-cining technology.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35246
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RUSCITO, GIOVANNI. "Materiali compositi a matrice polimerica autodiagnosticanti." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1226.
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L’attività di ricerca svolta è stata focalizzata sullo studio e la realizzazione di Materiali Autodiagnosticanti: ovvero materiali con la duplice funzione strutturale e di sensore.
I materiali scelti per questo scopo sono compositi a matrice polimerica, dato il loro vasto campo applicativo e la loro grande versatilità. Il materiale realizzato consta di due parti fondamentali: il rinforzo strutturale costituito da fibre di vetro in resina epossidica e l’elemento sensibile costituito da una fase elettricamente conduttrice in carbonio in forma di fibre lunghe unidirezionali o nanoparticelle o nanofibre disperse nella resina epossidica. I compositi ibridi, realizzati in forma di tondini mediante un processo di pultrusione manuale, sono costituiti dall’elemento sensibile interno coassialmente rivestito di vetroresina. In tutti i casi l’efficienza dell’autodiagnosi è stata valutata correlando la variazione di resistenza elettrica della fase conduttrice con il carico e/o la deformazione applicati all’intero composito.
Per ciascun tipo di elemento sensibile sono stati indagati aspetti precisi:
1. nel caso degli elementi sensibili in fibra di carbonio unidirezionali ci si è particolarmente soffermati sull’influenza della quantità di vetro esterna sulle proprietà di autodiagnosi;
2. nei provini con elementi sensibili realizzati con nano-particelle e nanofibre di carbonio in resina epossidica si è indagato l’effetto della tipologia di particelle impiegate (area superficiale, dimensione, aspect ratio, ecc.) sulle proprietà di conducibilità elettrica e di autodiagnosi.
I risultati dei sensori con fibra di carbonio hanno evidenziato che questo tipo di materiale non è particolarmente adatto ad una funzione di monitoraggio continuo della sollecitazione, bensì ha interessanti applicazioni quale “sensore di guardia” con comportamento tipo “on-off”. Ciò a causa del particolare meccanismo di conduzione che consente sempre un cospicuo passaggio di corrente fino alla rottura delle fibre di carbonio. La ricerca ha evidenziato che tale comportamento di guardia può essere influenzato dalla quantità di vetro che riveste l’elemento sensibile. In particolare, l’attivazione del segnale di guardia (resistenza elettrica pari ad infinito) può essere anticipato rispetto alla rottura finale del composito aumentando la quantità di vetro.
I sensori realizzati con nanoparticelle di carbonio hanno invece mostrato grande capacità di monitoraggio in continuo, e ciò a causa del fatto che in questi sistemi la conducibilità elettrica è associata ad un modello percolativo. All’aumentare del carico (e quindi della deformazione) del materiale, le particelle conduttrici vengono progressivamente allontanate le une dalle altre consentendo di registrare un graduale e continuo aumento della resistenza elettrica. In questi sistemi, tuttavia, la natura, morfologia, dimensione, area superficiale, ecc. delle nano-particelle influenzando notevolmente la formazione del network percolativo, influenzano conseguentemente anche le proprietà di autodiagnosi. Le particelle ad elevata area superficiale hanno mostrato le migliori proprietà di autodiagnosi.
Nel passaggio dalle nanoparticelle alle nano-fibre di carbonio non ha portato i miglioramenti attesti. Questo particolare sistema è stato indagato in quanto consente teoricamente di ottenere buona conducibilità elettrica con minore quantitativo di carica grazie all’elevato aspect ratio delle nanofibre, tuttavia la manifattura degli elementi sensibili è risultata estremamente complessa. Le nanofibre commerciali, infatti, vengono fornite in forma di aggregati micrometrici e che necessitano lunghe manipolazioni con solventi per essere disaggregati. Tali operazioni, possibili con limitate quantità di materiale, sono invece molto difficoltose e delicate quando applicate a sistemi più grandi quali la pultrusione impiegata per realizzare i materiali di questa sperimentazione. I sensori ottenuti in nano fibra di carbonio, frutto di un compromesso tra il livello di dispersione delle nanofibre nella resina e la processabilità, hanno dimostrando proprietà di autodiagnosi molto simili a quelle delle particelle di carbonio con area superficiale bassa, assai poco soddisfacenti.
I materiali risultati più idonei alle funzioni di autodiagnosi, ovvero quelli con elemento sensibile in nanoparticelle di carbonio ad elevata area superficiale, sono stati poi provati in condizioni pratiche di esercizio, quali rinforzi strutturali in travi di calcestruzzo. I risultati hanno mostrato che i materiali realizzati conservano le proprietà di autodiagnosi sotto carico anche se inseriti in sistemi massivi come il calcestruzzo e che, inoltre, grazie alla loro sensibilità è stato possibile monitorarne anche la fase di presa ed indurimento.The research carried out was focused on the study and production of Composite Smart Material: materials with the dual function: structural and sensor. The materials chosen for this purpose are polymer matrix composites, due to their vast application field and their versatility. The material produced consists of two basic parts: the structural reinforcement consists of glass fibers in epoxy resin and the sensible element consists of a phase-sensitive electrically conductive carbon in the form of unidirectional long fibers or nanoparticles or nanofibers dispersed in epoxy resin. The hybrid composite, realized in the form of rods by a process of pultrusion manual, consisting of the element sensitive internal coaxially coated fiberglass. In all cases the efficiency of smart properties was assessed by correlating the change in electrical resistance of the phase conductor with the load and / or deformation applied to the entire composite. For each type of sensor element have been investigated specific aspects: 1. in the case of sensitive elements in carbon fiber unidirectional one is particularly dwelt on the influence of the amount of exterior glass on the properties of self-diagnosis; 2. in samples with sensitive elements made of nano-particles and carbon nanofibers in epoxy resin was investigated the effect of the type of particles used (surface area, size, aspect ratio, etc..) on the properties of electrical conductivity and self-diagnosis. The results of the sensors with carbon fiber have shown that this type of material is not particularly suitable for continuous monitoring function of the stress, but has interesting applications such as "Sensor Guard" behavior such as "on-off". This is because of the particular mechanism that allows always run a large current passing through rupture of carbon fibers. Research has shown that this behavior may be influenced guard by the amount of glass that covers the sensing element. In particular, the activation of the signal call (electrical resistance equal to infinity) may be faster than the final break of the composite by increasing the amount of glass. The sensors made of carbon nanoparticles have shown great ability but continuous monitoring owing to the fact that in these systems, the electrical conductivity is associated with a percolation model. Increasing load (ie deformation) of the material, the conductive particles are gradually removed from each other allowing you to record a gradual and continuous increase in electrical resistance. In these systems, however, the nature, morphology, size, surface area, etc.. of nano-particles significantly influence the formation of the percolation network, thus also affecting the properties of self-diagnosis. Particles with high surface area showed the best properties of self-diagnosis. In the transition from nanoparticles to nano-carbon fibers did not lead to improvements attests. This particular system has been investigated theoretically since it allows to obtain good electrical conductivity with less quantity of charge thanks to the high aspect ratio of nanofibers, but the manufacturing of the sensing elements was extremely complex. The nanofibers trade, in fact, is provided in the form of aggregated micro and requiring lengthy manipulations with solvents to be broken. Such operations, possibly with small amounts of material, are very difficult and sensitive when applied to larger systems such as pultrusion designed to produce the materials of this trial. The sensors obtained in nano carbon fiber, a compromise between the degree of dispersion of nanofibers in the resin and processability, showed properties very similar to the self of carbon particles with low surface area, not very satisfactory. The materials are more appropriate to the functions of self-diagnosis or those with sensitive element in nanoparticles of carbon with high surface area, were then tested in practical conditions of operation, such as structural reinforcement in concrete beams. The results showed that the materials remain the property of self-made load even if incorporated into systems such as the massive concrete and that, furthermore, due to their sensitivity has been possible to also monitor the stage setting and hardening.
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Yar, Mazher Ahmed. "Development of Nanostructured Tungsten Based Composites for Energy Applications." Doctoral thesis, KTH, Funktionella material, FNM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-101319.
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Tungsten (W) based materials can be used in fusion reactors due to several advantages. Different fabrication routes can be applied to develop tungsten materials with intended microstructure and properties for specific application including nanostructured grades. Therein, innovative chemical routes are unique in their approach owing numerous benefits. This thesis summarizes the development of W-based composites dispersed-strengthened by rare earth (RE) oxides and their evaluation for potential application as plasma facing armour material to be used in fusion reactor. Final material development was carried out in two steps; a) fabrication of nanostructured metallic tungsten powder dispersed with RE-oxides and b) powder sintering into bulk oxide-dispersed strengthened (ODS) composite by spark plasma process. With the help of advanced characterization tools applied at intermediate and final stages of the material development, powder fabrication and sintering conditions were optimized. The aim was to achieve a final material with a homogenous fine microstructure and improved properties, which can withstand under extreme conditions of high temperature plasma. Two groups of starting materials, synthesized via novel chemical methods, having different compositions were investigated. In the first group, APT-based powders doped with La or Y elements in similar ways, had identical particles’ morphology (up to 70 μm). The powders were processed into nanostructured composite powders under different reducing conditions and were characterized to investigate the effects on powder morphology and composition. The properties of sintered tungsten materials were improved with dispersion of La2O3 and Y2O3 in the respective order. The oxide dispersion was less homogeneous due to the fact that La or Y was not doped into APT particles. The second group, Ydoped tungstic acid-based powders synthesized through entirely different chemistry, contained nanocrystalline particles and highly uniform morphology. Hydrogen reduction of doped-tungstic acid compounds is complex, affecting the morphology and composition of the final powder. Hence, processing conditions are presented here which enable the separation of Y2O3 phase from Y-doped tungstic acid. Nevertheless, the oxide dispersion reduces the sinterability of tungsten powders, the fabricated nanostructured W-Y2O3 powders were sinterable into ultrafine ODS composites at temperatures as low as 1100 °C with highly homogeneous nano-oxide dispersion at W grain boundaries as well as inside the grain. The SPS parameters were investigated to achieve higher density with optimum finer microstructure and higher hardness. The elastic and fracture properties of the developed ODS-W have been investigated by micro-mechanical testing to estimate the materials’ mechanical response with respect to varying density and grain size. In contrast from some literature results, coarse grained ODS-W material demonstrated better properties. The developed ODS material with 1.2 Y2O3 dispersion were finally subjected to high heat flux tests in the electron beam facility “JUDITH-1”. The samples were loaded under ELM-like thermal-shocks at varying base temperatures up to an absorbed power density of 1.13 GW/m2, for armour material evaluation. Post mortem characterizations and comparison with other reference W grades, suggest lowering the oxide contents below 0.3 wt. % Y2O3. As an overview of the study conducted, it can be concluded that innovative chemical routes can be potential replacement to produce tungsten based materials of various composition and microstructure, for fusion reactor applications. The methods being cheap and reproducible, are also easy to handle for large production at industrial scale.QC 20120827
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Mohammed, Reza Dave. "Material properties and fracture mechanisms of epoxy nano-composites." Thesis, Imperial College London, 2007. http://hdl.handle.net/10044/1/11296.
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Pallon, Love. "Polyethylene/metal oxide nanocomposites for electrical insulation in future HVDC-cables : probing properties from nano to macro." Doctoral thesis, KTH, Polymera material, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193591.
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Nanocomposites of polyethylene and metal oxide nanoparticles have shown to be a feasible approachto the next generation of insulation in high voltage direct current cables. In order to reach an operationvoltage of 1 MV new insulation materials with reduced conductivity and increased breakdown strengthas compared to modern low-density polyethylene (LDPE) is needed.In this work polyethylene MgO nanocomposites for electrical insulation has been produced andcharacterized both from an electrical and material perspective. The MgO nanoparticles weresynthesized into polycrystalline nanoparticles with a large specific surface area (167 m2 g–1). Meltprocessing by extrusion resulted in evenly dispersed MgO nanoparticles in LDPE for the silane surfacemodified MgO as compared to the unmodified MgO. All systems showed a reduction in conductivityby up to two orders of magnitude at low loading levels (1–3 wt.%), but where the surface modifiedsystems were able to retain reduced conductivity even at loading levels of 9 wt.%. A maximuminteraction radius to influence the conductivity of the MgO nanoparticles was theoretically determinedto ca. 800 nm. The interaction radius was in turn experimentally observed around Al2O3 nanoparticlesembedded in LDPE using Intermodulation electrostatic force microscopy. By applying a voltage on theAFM-tip charge injection and extraction around the Al2O3 nanoparticles was observed, visualizing theexistence of additional localized energy states on, and around, the nanoparticles. Ptychography wasused to reveal nanometre features in 3D of electrical trees formed under DC-conditions. Thevisualization showed that the electrical tree grows by pre-step voids in front of the propagatingchannels, facilitating further growth, much in analogy to mechanical crack propagation (Griffithconcept). An electromechanical effect was attributed as possible mechanism for the formation of the voids.Nanokompositer av polyeten och metalloxidpartiklar anses vara möjliga material att använda i morgondagens isolationshölje till högspänningskablar för likström. För att nå en transmissionsspänning på 1 MV behövs isolationsmaterial som i jämförelse med dagens polyeten har lägre elektrisk ledningsförmåga, högre styrka mot elektriskt genomslag och som kan kontrollera ansamling av rymdladdningar. De senaste årens forskning har visat att kompositer av polyeten med nanopartiklar av metalloxider har potential att nå dessa egenskaper. I det här arbetet har kompositer av polyeten och nanopartiklar av MgO för elektrisk isolation producerats och karaktäriserats. Nanopartiklar av MgO har framställts från en vattenbaserad utfällning med efterföljande calcinering, vilket resulterade i polykristallina partiklar med en mycket stor specifik ytarea (167m2 g-1). MgO-nanopartiklarna ytmodifierades i n-heptan genom att kovalent binda oktyl(trietoxi)silan och oktadekyl(trimetoxi)silan till partiklarna för att skapa en hydrofob och skyddande yta. Extrudering av de ytmodifierade MgO nanopartiklarna tillsammans med polyeten resulterade i en utmärkt dispergering med jämnt fördelad partiklar i hela kompositen, vilket ska jämföras med de omodifierade partiklarna som till stor utsträckning bildade agglomerat i polymeren. Alla kompositer med låg fyllnadsgrad (1–3 vikt% MgO) visade upp till 100 gånger lägre elektrisk konduktivitet jämfört med värdet för ofylld polyeten. Vid högre koncentrationer av omodifierade MgO förbättrades inte de isolerande egenskaperna på grund av för stor andel agglomerat, medan kompositerna med de ytmodifierade fyllmedlen som var väl dispergerade behöll en kraftig reducerad elektrisk konduktivitet upp till 9 vikt% fyllnadshalt. Den minsta interaktionsradien för MgO-nanopartiklarna för att minska den elektriska konduktiviten i kompositerna fastställdes med bildanalys och simuleringar till ca 800 nm. Den teoretiskt beräknade interaktionsradien kompletterades med observation av en experimentell interaktionsradie genom att mäta laddningsfördelningen över en Al2O3-nanopartikle i en polyetenfilm med intermodulation (frekvens-mixning) elektrostatisk kraftmikroskop (ImEFM), vilket är en ny AFM-metod för att mäta ytpotentialer. Genom att lägga på en spänning på AFM-kantilevern kunde det visualiseras hur laddningar, både injicerades och extraherades, från nanopartiklarna men inte från polyeten. Det tolkades som att extra energinivåer skapades på och runt nanopartiklarna som fungerar för att fånga in laddningar, ekvivalent med den gängse tolkningen att nanopartiklar introducera extra elektronfällor i den polymera matrisen i nanokompositer. Nanotomografi användes för att avbilda elektriska träd i tre dimensioner. Avbildningen av det elektriska trädet visade att tillväxten av trädet hade skett genom bildning av håligheter framför den framväxande trädstrukturen. Håligheterna leder till försvagning av materialet framför det propagerande trädet och förenklar på det sättet fortsatt tillväxt. Bildningen av håligheter framför trädstrukturen uppvisar en analogi till propagering av sprickor vid mekanisk belastning, i enlighet med Griffiths koncept.
QC 20161006
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Liu, Jing. "Carbon nanotube/polymer composites and novel micro- and nano-structured electrospun polymer materials." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/22673.
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Thesis (Ph. D.)--Textile and Fiber Engineering, Georgia Institute of Technology, 2007.Committee Chair: Kumar, Satish; Committee Member: Carr, Wallace; Committee Member: Graham, Samuel; Committee Member: Griffin, Anselm; Committee Member: Yao, Donggang.
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Medeiros, Araujo Thiago. "Single Polymer Micro- and Nano- Composites." Doctoral thesis, University of Trento, 2013. http://eprints-phd.biblio.unitn.it/972/1/Medeiros_Thesis_Final_Revised_Version.pdf.
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Due to an increasing attention to environment preservation and the need to accomplish new regulations, a general interest to improve the recyclability of composite materials has recently emerged. In order to fulfill this new requirements, a possible strategy could be represented by the development of so-called "single polymer composites" (SPCs), i.e. composite materials in which both matrix and reinforcement have the same chemical composition. The main advantage of SPCs is that, unlike traditional heterogeneous composites (such as glass- or carbon reinforced polymer composites), they can be entirely melted down at the end of the product life for recycling.
After an optimization of the annealing treatment to improve the mechanical properties and thermal stability of the reinforcing phase, SPCs containing Vectran® micro- and nano- fibers as a reinforcement were prepared, and their thermo-mechanical properties and recyclability were investigated using a multidisciplinary approach.
Single polymer micro composites (SPMCs) containing up to 30 wt% of reinforcing microfibers showed a outstanding improvement of tensile modulus (up to 160 %) compared with the unfilled matrix. FESEM observations evidenced some pull-out phenomena, indicating a poor interfacial adhesion. After a surface treatment on the reinforcement, a composite containing up to 20 wt% showed a remarkable improvement of almost 180% in the tensile modulus compared with the unfilled matrix. FTIR and thermal analysis evidenced its recyclability.
Single polymer nano composites (SPNCs) containing up to 10 vol% of reinforcing nanofibers showed an increase by almost 20% of their tensile modulus and strength in comparison with the unfilled matrix. Optical observations revealed a consolidation problem in the unfilled matrix due to the adapted film-stacking process used. However, the addition of the nanofibers in the composite eliminated the problem. Thermal analysis was used to ensure the SPNCs recyclability.
Vectran® single polymer micro- and nano- composites have been proven to be possible candidates to substitute traditional heterogeneous composites materials, with enhanced recyclability features.
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Kraus, Zachary. "Computational tools for preliminary material design of metals and polymer-ceramic nano composites." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51795.
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In this dissertation, algorithms for creating estimated potentials for metals and modeling of nano composites are developed. The efficacy of the algorithms for estimated potentials were examined. The algorithm was found to allow molecular dynamic and Monte Carlo modeling to be included in the potential building process. Additionally, the spline based equations caused issues with the elastic constants and Young’s modulus due to extra local minima. Two algorithms were developed for improved modeling of nano composites: one was a random number generation algorithm for initializing polymer, second was a bonding algorithm for controlling bonds between polymer and nano particle. Both algorithms were effective in their tasks. Additionally, the algorithms for improved nano composite modeling were used for preliminary material design of PMMA metal oxide nano composite systems. The results from the molecular dynamic simulations show the bonding between polymer matrix and nanoparticle has a large effect on the Young’s modulus and if this bonding could be controlled, the tensile properties of PMMA-metal oxide nano composites could be tailored to the applications’ requirements. The simulations also showed bonding had caused changes in the density of the material which than effected the energy on the polymer chain and the Young’s modulus. A model was than developed showing the relationship between density and the chain energy, and density and the Young’s modulus. This model can be used for a better understanding and further improvement of PMMA-metal oxide nano composites.
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Olea, Mejía Oscar Fernando Brostow Witold. "Micro and nano composites composed of a polymer matrix and a metal disperse phase." [Denton, Tex.] : University of North Texas, 2007. http://digital.library.unt.edu/permalink/meta-dc-5135.
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Beets, Nathan James. "Computational Studies of the Mechanical Response of Nano-Structured Materials." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/98468.
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In this dissertation, simulation techniques are used to understand the role of surfaces, interfaces, and capillary forces on the deformation response of bicontinuous metallic composites and porous materials. This research utilizes atomistic scale modeling to study nanoscale deformation phenomena with time and spatial resolution not available in experimental testing. Molecular dynamics techniques are used to understand plastic deformation of metallic bicontinuous lattices with varying solid volume fraction, connectivity, size, surface stress, loading procedures, and solid density.
Strain localization and yield response on nanoporous gold lattices as a function of their solid volume fraction are investigated in axially strained periodic samples with constant average ligament diameter. Simulation stress results revealed that yield response was significantly lower than what can be expected form the Gibson-Ashby formalism for predicting the yield response of macro scale foams. It was found that the number of fully connected ligaments contributing to the overall load bearing structure decreased as a function of solid volume fraction. Correcting for this with a scaling factor that corrects the total volume fraction to "connected, load bearing" solid fraction makes the predictions from the scaling equations more realistic.
The effects of ligament diameter in nanoporous lattices on yield and elastic response in both compressive and tensile loading states are reported. Yield response in compression and tension is found to converge for the two deformation modes with increasing ligament diameter, with the samples consistently being stronger in tension, but weaker in compression. The plastic response results are fit to a predictive model that depends on ligament size and surface parameter (f). A modification is made to the model to be in terms of surface area to volume ratio (S/V) rather than ligament diameter (1/d) and the response from capillary forces seems to be more closely modeled with the full surface stress parameter rather than surface energy.
Fracture response of a nanoporous gold structure is also studied, using the stress intensity-controlled equations for deformation from linear elastic fracture mechanics in combination with a box of atoms, whose interior is governed by the molecular dynamics formalism. Mechanisms of failure and propagation, propagation rate, and ligament-by-ligament deformation mechanisms such as dislocations and twin boundaries are studied and compared to a corresponding experimental nanoporous gold sample investigated via HRTEM microscopy. Stress state and deformation behavior of individual ligaments are compared to tensile tests of cylinder and hyperboloid nanowires with varying orientations. The information gathered here is used to successfully predict when and how ligaments ahead of the crack tip will fracture.
The effects of the addition of silver on the mechanical response of a nanoporous lattice in uniaxial tension and compression is also reported. Samples with identical morphology to the study of the effects of ligament diameter are used, with varying random placement concentrations of silver atoms. A Monte Carlo scheme is used to study the degree of surface segregation after equilibration in a mixed lattice. Dislocation behavior and deformation response for all samples in compression and tension are studied, and yield response specifically is put in the context of a surface effect model.
Finally, a novel bicontiuous fully phase separated Cu-Mo structure is investigated, and compared to a morphologically similar experimental sample. Composite interfacial energy and interface orientation structure are studied and compared to corresponding experimental results. The effect of ligament diameter on mechanical response in compressive stress is investigated for a singular morphology, stress distribution by phase is investigated in the context of elastic moduli calculated from the full elastic tensor and pure elemental deformation tests. Dislocation evolution and its effects on strain hardening are put in the context of elastic strain, and plastic response is investigated in the context of a confined layer slip model for emission of a glide loop. The structure is shown to be an excellent, low interface energy model that can arrest slip plane formation while maintaining strength close to the theoretical prediction.
Dislocation content in all samples was quantified via the dislocation extraction algorithm. All visualization, phase dependent stress analysis, and structural/property analysis was conducted with the OVITO software package, and its included python editor. All simulations were conducted using the LAMMPS molecular dynamics simulation package.
Overall, this dissertation presents insights into plastic deformation phenomena for nano-scale bicontinuous metallic lattices using a combination of experimentation and simulation. A more holistic understanding of the mechanical response of these materials is obtained and an addition to the theory concerning their mechanical response is presented.Doctor of Philosophy
Crystalline metals can be synthesized to have a sponge-like structure of interconnected ligaments and pores which can drastically change the way that the material chemically interacts with its environment, such as how readily it can absorb oxygen and hydrogen ions. This makes it attractive as a catalyst material for speeding up or altering chemical reactions. The change in structure can also drastically change how the material responds when deformed by pressing, pulling, tearing or shearing, which are important phenomena to understand when engineering new technology. High surface or interface area to volume ratios can cause a massive surface-governed capillary force (the same force that causes droplets of water to bead up on rain coat) and lead to a higher pressure within the material. The effect that both structure and capillary forces have on the way these materials react when deformed has not been established in the context of capillary force theory or crystalline material plasticity theory. For this reason, we investigate these materials using simulation methods at the atomic level, which can give accurate and detailed data on the stress and forces felt atom-by-atom in a material, as well as defects in the material, such as dislocations and vacancies, which are the primary mechanisms that cause the crystal lattice to permanently deform and ultimately break. A series of parameters are varied for multiple model systems to understand the effects of various scenarios, and the understanding provided by these tests is presented.
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Flanigan, Kyle Yusef. "Synthesis of HAP nano rods and processing of nano-size ceramic reinforced poly (L) lactic acid composites /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/10616.
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Olea, Mejia Oscar Fernando. "Micro and nano composites composed of a polymer matrix and a metal disperse phase." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc5135/.
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Low density polyethylene (LDPE) and Hytrel (a thermoplastic elastomer) were used as polymeric matrices in polymer + metal composites. The concentration of micrometric (Al, Ag and Ni) as well as nanometric particles (Al and Ag) was varied from 0 to 10 %. Composites were prepared by blending followed by injection molding. The resulting samples were analyzed by scanning electron microscopy (SEM) and focused ion beam (FIB) in order to determine their microstructure. Certain mechanical properties of the composites were also determined. Static and dynamic friction was measured. The scratch resistance of the specimens was determined. A study of the wear mechanisms in the samples was performed. The Al micro- and nanoparticles as well as Ni microparticles are well dispersed throughout the material while Ag micro and nanoparticles tend to form agglomerates. Generally the presence of microcomposites affects negatively the mechanical properties. For the nanoparticles, composites with a higher elastic modulus than that of the neat materials are achievable. For both micro- and nanocomposites it is feasible to lower the friction values with respective to the neat polymers. The addition of metal particles to polymers also improves the scratch resistance of the composites, particularly so for microcomposites. The inclusion of Ag and Ni particles causes an increase in the wear loss volume while Al can reduce the wear for both polymeric matrices.
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Lin, Wei-Fu, and 林韋甫. "Polythiophene block copolymer and nano-composite materials." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/235r9p.
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碩士國立臺北科技大學
有機高分子研究所
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Polythiophene is an important polymer,which can be used in OLED,feed effect transistor,and solar-cells.In this experiment, Thiophene with carboxylate functional groups are copolymerized with thiophene.Different compositions of random copolymers are synthesized in this research. Alternating copolymer are also synthesized. It is found that the alternating copolymer manifest excellent electrical conductivity. Their physical properties and elucidated by UV,NMR,and FTIR. The optoelectronic applications of the polythiophene will be elucidated.