Thesis (M.S.)--Florida State University, 2005. / Advisor: Namas Chandra, Florida State University, College of Engineering, Dept. of Mechanical Engineering. Title and description from dissertation home page (viewed Jan. 25, 2006). Document formatted into pages; contains x, 54 pages. Includes bibliographical references.

It has been found that the composites of carbon nanotubes (CNTs) and epoxy resin could greatly enhance damping ability while the stiffness is kept at a very high level. In this research, carbon nanotube enhanced epoxy resin is fabricated. The dynamic properties of the nanotube composites are evaluated. A testing apparatus for obtaining composite dynamic properties is set up and measurement procedures are given. Multiple groups of specimens are made for investigations. In particular, the loss factors together with dynamic stiffness are measured for the specimens with different CNT weight ratio. Experimental results show that CNT additive can provide the composite with several times higher damping as compared with pure epoxy. The composite is much stiffer than viscoelastic material (VEM) while the damping is comparable when strain is above certain level. In order to further study the damping mechanism of the CNT composite, models are developed. Composite unit cell models containing single CNT segments are built by using finite element method (FEM). Models with varying CNT orientations are considered in order to describe the behaviors of the randomly oriented CNTs inside the epoxy matrix. Composite loss factors are calculated based on the average ratio of the unit cell energy loss to the unit cell energy input. Calculated loss factors under different strain levels are compared to experimental results. With the validated model, parametric study is thereafter performed. Parameters such as CNT dimensions and CNT alignment orientation are studied. Those factors lead to higher composite damping capacity are identified. / by Dai, Ruoli. / "September 2007." / Adviser: Wei-Hsin Liao. / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4978. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 93-97). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2005. / Lawrence A. Bottomley, Committee Chair ; F. Levent Degertekin, Committee Member ; Jiri Janata, Committee Member ; Boris Mizaikoff, Committee Member ; Thomas M. Orlando, Committee Member ; Robert L. Whetten, Committee Member. Vita. Includes bibliographical references.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Mechanical and Aerospace Engineering." Includes bibliographical references (p. 150-153).

Thesis (Ph. D.)--University of Idaho, October 2006. / Major professor: Chien M. Wai. Abstract. Includes bibliographical references. Also available online in PDF format.

Yang, Li. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 67-72). / Abstract also in Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background and Motivation --- p.1 / Chapter 1.2 --- Objectives --- p.2 / Chapter 1.3 --- Contributions --- p.2 / Chapter 1.4 --- Organization of the Dissertation --- p.3 / Chapter 2 --- Carbon Nanotubes as Sensing Elements --- p.4 / Chapter 2.1 --- Introduction --- p.4 / Chapter 2.2 --- Introduction to Carbon Nanotubes --- p.4 / Chapter 2.3 --- Chemical Sensor Applications --- p.6 / Chapter 2.3.1 --- Semiconducting Sensors --- p.7 / Chapter 2.3.2 --- Dielectric Sensors --- p.8 / Chapter 2.3.3 --- Adsorption Based Sensors --- p.9 / Chapter 2.4 --- Dielectrophoresis of CNTs --- p.9 / Chapter 2.4.1 --- Theory and Methodology --- p.10 / Chapter 2.4.2 --- Basic CNTs Sensor Fabrication Process Using DEP Force --- p.13 / Chapter 2.4.3 --- Electronic-Grade Carbon Nanotubes --- p.13 / Chapter 2.4.4 --- Simulation --- p.14 / Chapter 2.5 --- Photodesorption Phenomenon --- p.16 / Chapter 2.5.1 --- Chemical Desorption Process Induced by UV Illumination --- p.16 / Chapter 2.6 --- Summary --- p.19 / Chapter 3 --- Design of NaOCl Sensors Based on EG-CNTs in Microfluidic System --- p.20 / Chapter 3.1 --- Introduction --- p.20 / Chapter 3.2 --- Chemical --- p.20 / Chapter 3.2.1 --- Introduction to Chemical Properties and Reactions --- p.21 / Chapter 3.2.2 --- Reagents --- p.23 / Chapter 3.3 --- Methods for Chemical Detection --- p.23 / Chapter 3.3.1 --- Hypochlorite Detection --- p.23 / Chapter 3.3.2 --- Chlorine Gas Detection --- p.24 / Chapter 3.4 --- Design and Fabrication --- p.26 / Chapter 3.4.1 --- Sodium Hypochlorite Sensor Using Microfluidic System --- p.26 / Chapter 3.4.2 --- Modified Design For Indirect Detection to Chlorine Gas --- p.29 / Chapter 3.5 --- Equipments --- p.30 / Chapter 3.5.1 --- Source Meter --- p.30 / Chapter 3.5.2 --- Pneumatic Pump --- p.31 / Chapter 3.5.3 --- UV Illumination Devices --- p.31 / Chapter 3.5.4 --- Experimental Setup --- p.32 / Chapter 3.6 --- Summary --- p.34 / Chapter 4 --- Results --- p.35 / Chapter 4.1 --- Introduction --- p.35 / Chapter 4.2 --- Processes of the Experiments --- p.35 / Chapter 4.2.1 --- Response to Static Solution --- p.35 / Chapter 4.2.2 --- Response to Fluid Flow --- p.36 / Chapter 4.2.3 --- Response to Gas --- p.36 / Chapter 4.3 --- Noise and Accuracy --- p.37 / Chapter 4.4 --- I-V Characteristics --- p.38 / Chapter 4.4.1 --- EG-CNTs Sensor --- p.38 / Chapter 4.4.2 --- Variation Under UV Illumination --- p.39 / Chapter 4.5 --- Responses to Sodium Hypochlorite Solution --- p.41 / Chapter 4.5.1 --- Typical Responses --- p.41 / Chapter 4.5.2 --- Selectivity --- p.44 / Chapter 4.5.3 --- Sensitivity --- p.45 / Chapter 4.5.4 --- Effect of Injection Flow Rate on Sensor Performance --- p.50 / Chapter 4.5.5 --- Effect of Volume on Sensor Performance --- p.51 / Chapter 4.5.6 --- Continuous Detection --- p.54 / Chapter 4.5.7 --- Operating Power Limit --- p.57 / Chapter 4.6 --- Response to Chlorine Gas by Modified Design --- p.59 / Chapter 4.7 --- Desorption Induced by UV Illumination --- p.60 / Chapter 4.8 --- Summary --- p.63 / Chapter 5 --- Conclusion --- p.64 / Chapter 5.1 --- Future Work --- p.65 / Chapter 5.1.1 --- Selectivity --- p.65 / Chapter 5.1.2 --- Gaseous Chlorine Detection --- p.66 / Chapter 5.1.3 --- UV-LED Induced Desorption --- p.66 / Chapter 5.2 --- Concluding Remarks --- p.66 / Bibliography --- p.67

Acrylic bone cement is widely used as a structural material in orthopaedics, dentistry, and orofacial surgery. Although bone cement celebrates four decades of success, it remains susceptible to fatigue fracture. This type of failure can directly lead to implant loosening, revision surgery, and increased healthcare expenditures. The mechanism of fatigue failure is divided into three stages: 1) fatigue crack initiation, 2) fatigue crack propagation, and 3) fast, brittle fracture. Adding reinforcing fibers and particles to bone cement is a proposed solution for improving fatigue performance. The mechanical performance of these reinforced bone cements is limited by fiber ductility, fibermatrix de-bonding, elevated viscosity, and mismatch of fiber size and scale of fatigue induced damage. In this dissertation, I report that adding small amounts (0% - 10% by weight) of multiwall carbon nanotubes (MWNTs) enhances the strength and fatigue performance of single phase bone cement. MWNTs (diameters of 10-9 10-8 m; lengths of 10-6 10-3 m) are a recently discovered nanomaterial with high surface area to volume ratios (conferring MWNT bone cement composites with large interfaces for stress transfer) that are capable of directly addressing sub-microscale, fatigue induced damage. MWNTs (2wt%) significantly increased the flexural strength of single phase bone cement by a modest 12%; whereas, similar additions of MWNTs dramatically enhanced fatigue performance by 340% and 592% in ambient and physiologically relevant conditions, respectively. Comparing the fatigue crack propagation behaviors of reinforced and unreinforced single phase bone cements revealed that the reinforcing mechanisms of MWNTs are strongly dependent on stress intensity factor, K, a numerical parameter that accounts for the combinatorial effect of the applied load and the crack size. As the crack grows the apparent stress at the crack tip intensified and the MWNTs lost their reinforcing capabilities. For that reason, it is likely that the predominant role of the MWNTs is to reinforce the bone cement matrix prior to crack initiation and during the early stages of crack propagation. Therefore, MWNTs are an excellent candidate for improving the clinical performance of bone cement, thereby improving implant longevity and reducing patient risk and healthcare costs.

MSc report presented to the University of the Witwatersrand In the fulfillment of the requirements for the degree of Master of Science in Engineering School of Chemical and Metallurgical Engineering Faculty of Engineering and the Built Environment University of the Witwatersrand Johannesburg April 2017 / Oil and gas operations produce high volumes of wastewater in the form of finely dispersed oil/ water (o/w) emulsions, which have detrimental effects on the environment. The current most feasible method used to mitigate the environmental impacts caused by the emulsion (produced water) from oil and gas operations is polymer membrane technology. However, polymer membranes are susceptible to fouling and concentration polarization, which leads to the necessity for frequent membrane replacement, thus loss of operating time and high operation cost. This motivates the need to investigate ways of modifying the polymer membrane in order to make it more resistant to fouling and concentration polarization. This study is concerned with circumventing the challenges experienced by polymer membrane during crude oil/ water mixture ultra-filtration by infusing the polymer membrane with nano particles. The aim of the research was to investigate the influence of addition of CNTs on the modified membranes in treatment of waste water from petroleum source. The Wet Impregnation method was used for the preparation of the bimetallic catalyst (Fe-Co catalyst supported on Zeolite), Chemical vapor deposition (CVD) method was used to prepare the carbon nanotubes (CNTs) and Phase inversion (PI) method was used for the preparation of the polymer nanocomposite membrane. The bimetallic catalyst was characterized using scanning electron microscope (SEM) and X-ray diffraction (XRD). The CNTs were characterized using Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and Transmission electron microscopy (TEM). The prepared polymer nanocomposite membranes were characterized using SEM, FTIR, goniometer (for contact angles) and TAXT plus texture analyzer (for tensile strength test). Functionalized carbon nanotubes were used as membrane fillers or modifiers to improve the filtration properties of the polymeric membrane, ultimately forming nanocomposite polymer membranes. This increased hydrophilicity, chemical, mechanical and physical properties of the polymer membrane, made them to perform better during filtration than pristine polymer membranes. The performance of the nanocomposite membranes were evaluated and it was determined that the nanocomposite polymer membrane with a loading 0.4 wt.% functionalized carbon nanotubes performed better than pristine membrane and other CNTs loaded nanocomposite polymer membranes. The pristine membrane (0 wt% CNTs) showed a higher contact angle (79o) which crosses ponds to the inability to soak up water. The 0.4 wt% nanocomposite polymer membrane showed the lowest contact angle of 72 o, this validated an improvement in the properties of the membrane, in particular hydrophilicity. The 0.4 wt% nanocomposite polymer membrane showed a superior mechanical strength, with a breaking force at 4 N relative to the other membranes of the same thickness. 0.4 wt% nanocomposite polymer membrane showed the highest permeate flux of 120 L/m2.h compared to the pristine membrane, which showed a permeate flux of 63 L/m2.h. The permeate flux of 0.4 wt% nano-composite polymer membrane increased with the operating pressure. / MT 2018

Nenhuma / Desde que as singulares propriedades mecânicas e condutoras dos nanotubos de carbono (NCs) estão associadas a tubos individuais isolados, a dispersão e estabilização de seus feixes em diferentes líquidos são de extrema importância em estudos fundamentais e aplicados. Solventes do tipo amida são atualmente considerados os melhores candidatos, dentre os solventes orgânicos, à dispersão quantitativa dos feixes de nanotubos, sendo que a funcionalização das paredes dos tubos favorece essa dispersão em determinados meios. Amostras brutas de nanotubos de carbono são compostas por feixes contendo até centenas de tubos com distribuição em diâmetro, comprimento, quiralidade e caráter eletrônico, unidos por interações de van der Waals. Para a dispersão desses feixes, o potencial atrativo entre os tubos deve ser balanceado por um potencial repulsivo. Assim, o custo energético das interações nanotubosolvente, que depende fortemente da composição química da superfície dos tubos e das propriedades dielétricas do meio, precisa ser entendido. Teorias de solubilidade têm sido recentemente aplicadas no entendimento dos sistemas nanotubo-solvente. Nelas, a dispersão é favorecida quando os parâmetros de solubilidade do soluto e do solvente têm valores próximos. Nos parâmetros de Hansen, contribuições de energias dispersivas (dd), dipolares (dp) e de ligação de hidrogênio (dh) são consideradas nas interações intermoleculares. O parâmetro de Flory-Huggins (χ) estima a diferença de interação entre o soluto e o solvente, podendo ser expresso em termos dos parâmetros de Hansen. Neste trabalho, apresentamos um estudo sistemático da dispersão de nanotubos de carbono de parede única, como preparados e funcionalizados com grupos ácidos contendo oxigênio, em solventes do tipo amida. As interações nanotubos-solvente foram analisadas em termos dos parâmetros de solubilidade de Hansen e de Flory-Huggins. Por refluxo em solução de HNO3 diluída, quantidades similares (~ 0,3 mmol/g C) de grupos ácidos carboxílicos e hidroxílicos foram covalentemente introduzidos à superfície dos tubos, sem criar defeitos adicionais ou destruir tubos de diâmetros menores. Os materiais de partida e funcionalizado foram amplamente caracterizados por termogravimetria, microscopia eletrônica de varredura e transmissão, titulação potenciométrica e espectroscopias por dispersão de energia, Raman, na região do infravermelho e de fotoelétrons excitados por raios X. As dispersões obtidas por sonificação/centrifugação dos NCs, antes e após funcionalização, em N-metilpirrolidona (NMP), N,N-dimetilformamida (DMF), N,N-dimetilacetamida (DMA), Ndodecilpirrolidona (N12P) e ciclohexilpirrolidona (CHP) foram caracterizadas por espectroscopia de absorção óptica na região do ultravioleta-visível (UV-Vis). Em estudo de absorbância em função da concentração, foram estimados os limites de dispersão e os coeficientes de absorção dos nanotubos de carbono em cada solvente. A presença dos grupos funcionais aumentou a dispersabilidade dos tubos em NMP, DMF e DMA, mas diminuiu em N12P e CHP. Os coeficientes de absorção, entretanto, diminuíram para todos os solventes após oxidação, refletindo a diminuição da probabilidade da transição p-p* com a funcionalização e a interação com o solvente. Os parâmetros de solubilidade de Hansen e de interação de Flory-Huggins foram calculados para as amostras antes e após funcionalização, permitindo uma análise termodinamicamente quantitativa das interações intermoleculares nos sistemas estudados. Os valores dos parâmetros de Hansen obtidos para a amostra bruta foram dD = 18,0 MPa1/2, dP = 7,4 MPa1/2 e dH = 6,8 MPa1/2, enquanto aqueles para a amostra funcionalizada foram dD = 17,4 MPa1/2, dP = 12,0 MPa1/2 e dH = 9,2 MPa1/2. Em comparação com valores tabelados para os solventes, o parâmetro de energia dispersiva mostrou-se dominante na dispersão dos tubos não-funcionalizados, enquanto interações dipolares e ligações de hidrogênio exerceram uma maior influência na dispersão dos tubos funcionalizados com grupos oxigenados ácidos. Os parâmetros de interação de Flory-Huggins estimados mostraram que os sistemas com maior afinidade foram a amostra bruta dispersa no solvente CHP e a amostra funcionalizada dispersa nos solventes NMP, DMA e DMF.

In the first part, the mechanisms for the dissociation of TPA are studied under three types of conditions. The unimolecular dissociation is initiated by the breaking of either the N-Calpha and Calpha -Cbeta bonds and leads to many complicated processes. Within the confined space inside neutral zeolite channels, the diffusion of H radicals enhances a cycle of reactions, which accounts for the experimental observation of dipropylamine and monopropylamine. In the presence of an acidic site, the dissociation of TPA goes through catalyzed successive steps to produce ammonia and propylene molecules. / In the last part, two distinct paths are proposed to investigate the carbon nanotube growth mechanism using benzene as the growth seed and propylene as carbon resource. There is an incremental aromatization process, involving both alkylation and dehydrogenation, that leads to linked aromatic rings to form either (3,3) tube or (4,2) tube. Two paths are identified, one via toluene and the other via cumene. The cumene path is more favorable as the barrier is significant lower. / In the second part, A T5 cluster model is used to investigate mechanisms of propylene aromatization to benzene, which involves chemisorption, dimerization, cyclization and dehydrogenation. Propylene can be chemisorbed to form two distinct products, n-propoxide and i-propoxide, which can further be dimerizated to form longer chain olefins 1-hexene and 2-hexene (from n-propoxide), and 4-methyl-1-pentene and 4-methyl-2-penetene (from i-propoxide). Initiated by H2 elimination, these dimerization products can further go through cyclization process to generated either 6-member ring cyclohexene or 5-member ring methyl-cyclopentene. Catalyzed by zeolite, cyclohexene can directly dehydrogenate to form benzene whereas methyl-cyclopentene can dehydrogenate to form fulven, an isomer to benzene. Under acidic zeolite environment, a fulvene can readily be transformed to the thermodynamically more stable benzene. / The growth mechanisms of mono-sized and parallel-aligned single wall carbon nanotube (CNT) in the microporous channels of AlPO4-5 are investigated by density functional theory calculations. Detailed mechanisms are proposed for the decomposition of TPA, the formation of aromatic ring, and the growth of carbon nanotubes. / Liu, Jianwen. / Adviser: Zhifeng Liu. / Source: Dissertation Abstracts International, Volume: 70-09, Section: B, page: . / Thesis submitted in: December 2008. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 98-99). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.