Dissertations / Theses on the topic 'Greases- Nano composite materials'
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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.
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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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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.
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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Singh, Jayant. "Tribo-Dynamics and rheological studies of newly developed nano-composite greases." Thesis, 2018. http://eprint.iitd.ac.in:80//handle/2074/7924.
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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
99
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.
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Chen, Yi-Jie, and 陳奕杰. "Smart Nano - composite Materials with Self - health Monitoring Ability." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8d43an.
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碩士國立臺灣大學
機械工程學研究所
105
Fiber reinforced plastic (FRP) has become increasingly used in industries such as aerospace, shipbuilding and automotive, leading to the need of monitoring the structural integrity of composite structures and materials. The use of traditional non-destructive testing (NDT) for composite materials has practical limitions. By adding carbon nanotubes to produce a hybrid-fiber-reinforced plastic may provide the material a possibility for self-health monitoring this work aim at investigate the possibility more usely. Firstly we compard the conductivity of masterbatch nanotubes, and the amine-functionalizes, Oxygen-functionalizes, Carboxylic acid functionalized of MWCNTs in epoxy resin under different dispersion parameters. It was concluded that the use of amine functionalized MWCNTs gave the best conductivity. Secondly for the dispersion parameters was compare, by the distribution of resistance and reproducibility of results as well as SEM observation. It was concluded that Ultrasonic agitation for 1hr and mixing for 20mins way the High speed homogenizer mixing (HSM) gave the optimum results. Thirdly the methods for mounting electrodes on composite specimens were investigated. It was found that by embedding electride under the specimens end tabs give the best results. Lastly we compared the resistance of the three conductive materials of CE, CNT CE and CNT GE for the conductive damage monitoring and discusses the dispersion time on the sensitivity of the sensing. The results indicated the most stable effect was associated CNT GE effect, and the dispersion time does affect the sensitivity of the sensing.
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Cheng, Ming-Yao, and 鄭銘堯. "Novel Synthesis of Nano-/Nano-composite Materials in Confined Space of Mesoporous Materials and Their Electrochemical Properties." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/g5mr8x.
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博士國立臺灣科技大學
化學工程系
95
In this study, a general route, named as a hydrophobic encapsulation route, has been successfully developed for the exclusive formation of inorganic materials in the confined spaces of porous hosts. The concept was first demonstrated by the formation of NiO nanoparticles in the pore channels of mesoporous SBA-15. The synthesized NiO/ SBA-15 nanocomposites shows superior nano-architecture in the pore channels of SBA-15 that the formed NiO nanoparticles are highly uniform and well-distributed in the confined space without blocking the pore channels. The novel nano-architecture of the synthesized NiO/ SBA-15 is of great potential for advanced heterogeneous catalyst applications. The blockage problem usually encountered in mesoporous materials can be avoided by the developed route. Furthermore, the high thermal stability of the synthesized NiO/ SBA-15 was revealed by XRD and TPR analyses, indicating strong interaction of NiO nanoparticles with silica framework (average grain size of NiO only slightly increases from 2.83 (heated at 400 oC) to 3.69 nm (heated at 900 oC)). The ultra fine NiO nanoparticles extracted from the synthesized NiO/ SBA-15 shows excellent electrochemical properties as Li-ion battery anodes. The excellent capacity retention behavior for the ultra fine NiO nanoparticles is displayed for the first time even cycling at higher C rate. It may be contributed by the outstanding stability of the electrode made of the ultra fine NiO nanoparticles whose grain size are too small to be pulverized electrochemically (3.11 nm). The smaller hysteresis loop between the charge and discharge plateau indicates the less internal resistance of the electrode made of the synthesized ultra fine NiO nanoparticles compared to the commercial NiO nanoparticles. In addition, a novel concept for 3-D nano-current collector/ nano-electrolyte architecture as an anode material of Li-ion battery is introduced and demonstrated. The nano-architecture can be constructed by taking mesoporous CMK-3 as 3-D nano-current collector and the pore channels of the CMK-3 as the said nano-electrolyte after impregnating with liquid electrolyte. The NiO nanoparticles can be synthesized in the confined space of CMK-3 by the developed hydrophobic encapsulation route together with the nature of spontaneous oxidation of metal nanoparticles. The capacity retention and rate capability of the NiO/CMK-3 nanostructured materials applied in a lithium battery are excellent, indicating the effectiveness of the novel electrode nano-architectured by the developed concept. The concept can be applied to other materials for advanced electrochemical devices with proper modification of the process.
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shieh, Yi jiun, and 謝宜君. "Synthesis and Chacracterization of nano-silver wires/graphene composite materials." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/99232621260551263810.
Full textAbstract:
碩士明新科技大學
化學工程與材料科技系碩士班
103
Graphene is the thinnest and hardest nano-materials. Graphene have unique structure and excellent properties which has a wide range of applications in optoelectronics, gas sensors, capacitor, transparent conductive touch panel, composite and hydrogen storage materials. Metal silver has excellent electrical and thermal conductivity. Nano silver wires (NSWs) with high aspect ratio interlace into the network structure then will increase the conductivity. It is anticipated that replace ITO to use as multi-point touch panel material. In conventional, hydrothermal method was used to synthesis NSWs that need more than 2 hr procedure time. It has time-consuming and complex procedure problems. In this thesis, graphene were synthesized on copper foil by thermal chemical vapor deposition. Wrinkled surface of copper due to copper were deposited on a rotating drum and then peel off to form a rolled foil. The optimal copper substrate electropolishing pretreatment parameters were investigated and then a high quality graphene were obtained. The results show that a high quality graphene can be obtained by copper substrate with 60 min electropolishing pretreatment time, and using PEG/H3PO4 ratio of 1：3. NSWs was rapid synthesize by microwave polyol method. The results show that 0.07 M PtCl2, 0.2 M PVP were added into 0.4 M AgNO3 at 160℃ ,with 2 min reaction time , under 500W power. The high quality nano silver wires were obainted. The NSWs were coated on graphene/ITO to prepare a composite. The addition amount of NSW and procedure parameters was studied to improve the conductivity and transmittance of composite. The optimal results show that 1 mg NSWs were dipping into 3 mL Ethanol, with 5000 rpm spin coating on graphene. Resistance and transmittance of NSWs/graphene composite are 30.55 Ω/□, and 95.47% respectively. It is apparent improvement characteristic properties of graphene thin films.
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Tasy, Ryh-Shin, and 蔡日新. "Preparation and Properties of Polyimide/Nano-Gold Particle Composite Materials." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/5nhbnq.
Full textAbstract:
碩士中原大學
化學研究所
93
Abstract This thesis is mainly focused on the preparation and property studies of nanocomposite materials, which containing the dispersed phase of nano-scale gold particles and polyimide (PI) matrix. First of all, the nano-scale gold particles were generated through processing the reduction reactions of HAuCl4 compound by citrate. Subsequently, suitable amount of as-prepared gold nanoparticles were homogeneously added into the poly(amic acid) solution through the direct solution dispersion technique, followed by casting the as-mixing solutions on inorganic glass substrate and then treated by heated up to 300�aC to complete the thermal imidization reactions of PI, yielding the polyimide-gold nanocomposite materials. The as-prepared nanocomposite materials were then characterized by FTIR, XRD and TEM. Effect of material composition on the gas permeability, thermal stability, mechanical strength, thermal transport, surface wettability were investigated based on the studies of gas permeability analyzer (TGA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), hot disk (HD) and contact-angle measurement, respectively.
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LU, YEN-CHEN, and 呂彥辰. "The Study of PP/Sulfonated SiO2 Nano-particles Composite Materials." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/50577317114544142179.
Full textAbstract:
碩士南臺科技大學
化學工程與材枓工程系
105
In this study, the silica nanoparticles were prepared by sol-gel method, and sul-fonated silica nanoparticles were prepared by sulfonation modification procedure. MAH-PP was used as a mixing device. And then the properties of the composite membrane were studied. The results showed that the silica nanoparticles prepared by the nano-particles of silica by SEM, found that the uniform spherical silica nanoparticles, and with the polymerization time increases, the particles also will increase. (Si-O-Si) absorption peak at 766cm-1 and asymmetric stretching vibration of Si-O-Si (Si-O-Si) were measured by FT-IR. (C=C), the absorption peaks appear between 1000 and 1200 cm-1, and the carbon-carbon double bonds (C=C) of the vinyltrimethoxysilane are incorporated into the silica nanoparticles Peaks appear at 1410 cm-1 and 1602 cm-1. The sulfonated silica nanoparticles were detected by FT-IR. It was found that the absorption peak of benzene ring was 1129cm-1 due to the addition of sodium styrenesulfonate as the sulfonating agent to the silica nanoparticles. Benzene (S=O) absorption peak at 1040 cm-1 and asymmetric vibrational sulphonic acid (S=O) absorption peak at 1200 cm-1 and 100 cm-1, respectively. The absorption peak of the symmetric vibrating sulphonate (S=O) The hydroxyl (OH) absorption peak appears at about 3400 cm-1 because the sulfonate ion has the property of adsorbing water, which confirms the presence of sulfonate groups in the sulfonated silica nanoparticles. The sulfonation degree of the sulfonated silica nanoparticles was measured by the sulfonation degree. It was found that the sulfonation time of the polymerized silica nanoparticles increased with the sulfonation time, and the sulfonation degree also increased. MAH-PP MAH grafted by the determination that the addition of 4g MAH has the highest grafting rate, so choose to add 4g of MAH and different time polymerization of silica nanoparticles sulfonated at different times to do the sulfonated bis Silicon oxide nanoparticles mixed into a composite membrane. MAH grafting rate of the composite membrane was determined that, in the acidic environment, the sulfonate itself may cause PP oxidation, leading to MAH more easily connected, so with the sulfonation time increases, MAH grafting rate increases. The smaller the corresponding frequency, the larger the agglomeration size of the composite membrane. Because ε "/ ε 'is large, the sulfonic acid group may be relatively sparse, and the interfacial polarization value of the composite film is relatively sparse. The larger the corresponding frequency, the smaller the agglomeration size of the composite membrane, because ε "/ ε 'is small, it is possible that the sulfonic acid group is more compact. The composite film can be obtained by puncture analysis, PP film itself, if not add other materials, then, PP surface pores will be relatively small, relatively high crystallinity, which leads to the highest puncture value, the highest tensile strength, MAH-PP lower crystallization , But increased the attraction between the MAH groups, resulting in decreased puncture value, sulfonated silica nanoparticles added MAH-PP internal significantly reduced crystallinity, but will attract each other due to polarity, the longer the time of sulfonation , The greater the relative attractiveness, so the puncture value will be higher and higher. It can be found that the number of hydrogen ions flowing in the MAH-PP itself can not be flowed by the MAH, so the number of hydrogen ions is relatively low, the current will be lower when the voltage is on, Sulfonation time is shorter, representing the sulfonation degree is relatively low, the number of flowable hydrogen ions is relatively small, in the pass on the voltage when the current is relatively low; sulfonation time is longer, on behalf of the sulfonation degree is relatively high, The number of hydrogen ions can flow more, in the pass on the voltage when the current is relatively high.
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Wang, Chih-Wei, and 王志偉. "Preparations of Epoxy/Silica Nano-composite Materials via Sol-Gel Process." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/10236744483061206908.
Full textAbstract:
碩士淡江大學
化學學系碩士班
95
Epoxy/silica nano-composite materials are prepared by silane-terminated epoxy resin with tetraethoxysilane (TEOS) and nano-silica via a sol-gel process, respectively. The silane-terminated epoxy resin (EP-APTES) is obtained from a ring opening reaction of an epoxy resin (e.g. its EEW is 818) with 3-aminopropyltriethoxysilane (APTES). The nano-composites are prepared by mixing EP-APTES with various dosages of TEOS and nano-silica (dispersed in methanol solution), respectively in 5, 10, or 20 phr. The epoxy/silica nano-composites formation are catalyzed in acidic (pH= 3) and basic (pH=10) conditions, respectively via a sol-gel process. The performance properties, such as gel content, pencil hardness, contact angle, thermal stabilities and etc. of these resulted epoxy/silica nano-composites are enhanced with increasing silica dosage. Silica nano-size distribution of nano-composites from acidic condition is far better than that of obtained from base catalytic condition, which are demonstrated by SEM observations.
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Tsai, Ping-Huan, and 蔡秉桓. "Fabrication and Field Emission Characteristics of Carbon-Based Nano Composite Materials." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/qpjck9.
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Ramsaroop, Avinash. "Fracture properties of fibre and nano reinforced composite structures." Thesis, 2007. http://hdl.handle.net/10321/142.
Full textAbstract:
Thesis (M.Tech.: Mechanical Engineering)-Dept. of Mechanical Engineering, Durban University of Technology, 2007
xvi, 123 leavesInterlaminar cracking or delamination is an inherent disadvantage of composite materials. In this study the fracture properties of nano and fibre-reinforced polypropylene and epoxy composite structures are examined. These structures were subjected to various tests including Single Edge Notched Bend (SENB) and Mixed Mode Bending (MMB) tests. Polypropylene nanocomposites infused with 0.5, 1, 2, 3 and 5 weight % nanoclays showed correspondingly increasing fracture properties. The 5 weight % specimen exhibited 161 % improvement in critical stress intensity factor (KIC) over virgin polypropylene. XRD and TEM studies show an increase in the intercalated morphology and the presence of agglomerated clay sites with an increase in clay loading. The improvement in KIC values may be attributed to the change in structure. Tests on the fibre-reinforced polypropylene composites reveal that the woven fibre structure carries 100 % greater load and exhibits 275 % lower crack propagation rate than the chopped fibre specimen. Under MMB conditions, the woven fibre structure exhibited a delamination propagation rate of 1.5 mm/min which suggests delamination growth propagates slower under Mode I dominant conditions. The woven fibre / epoxy structure shows 147 % greater tensile modulus, 63 % greater critical stress intensity factor (KIC), and 184 % lower crack propagation rate than the chopped fibre-reinforced epoxy composite. MMB tests reveal that the load carrying capability of the specimens increased as the mode-mix ratio decreased, corresponding to an increase in the Mode II component. Delamination was through fibre–matrix interface with no penetration of fibre layers. A failure envelope was developed and tested and may be used to determine the critical applied load for any mode-mix ratio. The 5 weight % nanocomposite specimen exhibited a greater load carrying capability and attained a critical stress intensity factor that was 10 % less than that of the fibre-reinforced polypropylene structure, which had three times the reinforcement weight. Further, the nanocomposite exhibited superior strain energy release rates to a material with ten times the reinforcement weight. The hybrid structure exhibited 27 % increase in tensile modulus over the conventional fibre-reinforced structure. Under MMB conditions, no significant increase in load carrying capability or strain energy release rate over the conventional composite was observed. However, the hybrid structure was able to resist delamination initiation for a longer period, and it also exhibited lower delamination propagation rates.
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Chan, Chia-Hua, and 詹佳樺. "Via Sol-Gel Porcess to Synthesize Nano-Composite Materials and Photonic Crystal." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/60449483051799664940.
Full textAbstract:
博士國立中央大學
化學工程與材料工程研究所
93
This study was written to serve as a novel technique to fabricate nano-composite materials and photonic crystals via sol-gel process. In Chapter 2, the organic-inorganic nano-composite materials have been prepared by using methyl methacrylate (MMA), 2-Hydroxyethyl methacrylate (HEMA) and tetraethoxysilane (TEOS) via the sol-gel process. Under the acid condition, 2,2’-azobisisobutyronnitrile (AIBN) was used as the initiator for the polymerization of MMA and HEMA monomer and various amounts of water was added for synthesizing the SiO2 network. It was found that transparent nano-composite materials could be prepared when acid catalyst and appropriate ethanol added into the reaction system. The products were characterized by GPC, ASAP, SEM and TGA thermograms. The results of TGA analysis show that the thermal properties of the PMMA-SiO2 and PHEMA-SiO2 nano-composite materials are improved. In Chapter 3, the organic materials with SiO2 or ZrO2 highly coating microcapsule were successfully prepared in the alkaline condition. The products were characterized by SEM and TGA and DSC thermograms. The heat resistance of the products was improved more than 50℃,and the scale of the products were between 0.2~3 um. In Chapter 4, I propose a novel technique to fabricate a free-standing three-dimensional photonic crystal by self-assembling the colloidal microspheres with controllable thickness from the air–liquid interface. Highly ordered three-dimensional photonic crystals are formed by polymethylmethacrylate or polystyrene monodisperse microspheres. We also demonstrate the fabrication technique of the free-standing inversed opals by removing the microspheres using calcination. The free-standing photonic crystal structures can be used for nano-photonic circuits, white-light LEDs or as a photocatalyst.
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Lan, Sung-Chi, and 藍松騏. "Study and Development on the Flexible-sensor Composed of Nano composite Materials." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/skjuwq.
Full textAbstract:
碩士國立臺北科技大學
機電整合研究所
98
This study has developed a Nano Composite Materials, made by high polymer material and nano powder materials, which can be used for flexible measure sensor. The high polymer material has the characteristics of soft and flowing ability in colloidal patterns. Moreover, this high polymer material should have the capacity of high load without damage after solidified. The characteristics of flowing ability of the high polymer material can reduce the possible difficulty in the printing process. Therefore, the PDMS high polymer material is used as the substrate materials of sensor. However, all polymer materials are almost in insulated state. In order to make it have conductive characteristics, therefore, we mix the high polymer material with conductive powder in different proportions according to their different characteristics to perform the experimental study. This study has found the suitable conductive composite material for the substrate of pressure sensor. We have also developed the best fabricated process for this printable conductive composite materials and the printing process which can be used in the fabrication of array-type flexible sensor system. Its feasibility has been confirmed through fabricating a prototype.