Dissertations / Theses on the topic 'Carbon nano-composites'

This thesis reports a study of the effects on processing and properties of incorporating nano-scale reinforcements (multiwall carbon nanotubes, MWCNTs) in the matrix of epoxy- carbon fibre (CF) laminate composites to produce multi-scale composites (M-SC). The main aim of this research was to study the effects of MWCNTs on matrix toughening and the through-thickness properties of M-SCs based on a commonly used aerospace grade epoxy resin — triglycidyl-p-aminophenol (TGPAP) cured with diaminodiphenyl sulphone (DDS). In order to improve resin processing, diglycidyl ether of bisphenol F (DGEBF) was added into the TGPAP/DDS system as a reactive diluent. Factorial experimental design (FED) was used to optimize the composition of this tri-component system to obtain high Tg and low resin viscosity, which gave a TGPAP/DGEBF/DDS system with 30.56 wt.% of DGEBF and a chemical stoichiometry of 0.5. Three types of MWCNTs were used; as-received (AR-), base-washed (BW-) and amine functionalized (NH2-). These were shear-mixed with both the bi- and tri-component systems using a 3-roll mill to produce nanocomposite matrices (NCM). The curing behaviour, dispersion state of MWCNTs in the resin and processability of NCMs were studied to decide upon the preparation method for the final M-SC. The fracture toughness (KIC) and the flexural properties of NCM were affected by both MWCNTs and the matrix type; thus KIC increased by up to 8 % in TGPAP/DDS NCM but decreased by 23% in TGPAP/DGEBF/DDS NCM with 0.5 wt.% AR-CNTs. The addition of both non-functionalized and functionalized MWCNTs increased the flexural modulus. The failure mechanism of NCMs was found to be dominated by the size and distribution of CNT aggregates and the behaviour of MWCNTs, both those dispersed in the matrix and in aggregates. The addition of functionalized MWCNTs increased the interfacial bonding between MWCNT and epoxy resin and thus improved the mechanical properties. All the NCM systems were taken forward to manufacture M-SC using a hybrid resin film infusion (RFI)/hot press process. The fibre volume fraction and the void content could be controlled at 43 ± 5 % for M-SC with TGPAP/DDS NCM and 60 ± 6 % for M-SC with TGPAP/DGEBF/DDS NCM. M-SCs were characterised using a range of tests, including flexural, interlaminar shear strength (ILSS), mode-II interlaminar fracture toughness (GIIC), low velocity impact and compression after impact (CAI). The most obvious improvement occurred for the M-SC with tri-component system with 0.5 wt.% CNTs, whereILSS increased by 16 % upon adding NH2-CNTs and GIIC increased significantly on addition of 0.5 wt.% AR-CNTs and NH2-CNTs, by 85% and 184% respectively. However the effect of MWCNTs on other properties was at best marginal. For example, for the M-SC with TGPAP/DDS, the flexural modulus and ILSS only increased by 4.1 % and 2.3 % with 0.5 wt.% AR-CNT.

Yes<br>Owing to their small size, good wettability, uniform dispersion ability and high thermal properties, the nickel-plated carbon nanotubes (Ni-CNTs) with different aspect ratios are used to reinforce reactive powder concrete (RPC) through modifying the nano/micro- structural units of concrete. Incorporating only 0.075 vol% of Ni-CNTs (0.03 vol% of CNTs) can significantly increase mechanical properties of RPC. The enhancement effect on compressive strength caused by the incorporation of Ni-CNTs with aspect ratio of 1000 reaches 26.8%/23.0 MPa, mainly benefiting from the high polymerization C-S-H gels, low porosity, and refined pore structure. The 33.5%/1.92 MPa increases of flexural strength can be attributed to the decrease of large pore, original cracks, molar ratio of CaO to SiO2, and gel water content when Ni-CNTs with aspect ratio of 125 are added. Ni-CNTs with aspect ratio of 1500 have the largest utilization rate of being pulled-out, resulting from the improvement of dispersibility and the pining effect of nickel coating and then leading to the increased toughness. Therefore, incorporating Ni-CNTs can fundamentally modify the nano/micro- scale structural nature of RPC, providing a bottom-up approach for controlling the properties of RPC.<br>Funding supported from the National Science Foundation of China (51908103 and 51978127) and the China Postdoctoral Science Foundation (2019M651116).<br>The full-text of this article will be released for public view at the end of the publisher embargo on 7th Dec 2021.

Actualment hi ha una gran preocupació sobre l'ús de pesticides en l'agricultura i els seus possibles efectes secundaris. Això fa que el desenvolupament de sistemes de detecció sensibles i robustos sigui un pas important en aquesta direcció. D'altra banda, les nano-cebes de carboni (CNOs) són materials molt atractius i prometedors amb estructures definides i propietats electroquímiques notables que amb prou feines s'han estudiat en biosensors. L'objectiu general d'aquesta tesi és estudiar la interacció de diferents plaguicides amb peroxidasa i tirosinasa amb l'objectiu de desenvolupar biosensors per a la seva detecció basats en elèctrodes modificats amb CNOs. Per aconseguir aquest objectiu general, s'ha estudiat: 1) la inhibició de les activitats de peroxidasa i tirosinasa per tres dels plaguicides més utilitzats (2,4-D, 2,4,5-T i glifosat), 2) l'ús d'CNOs oxidades com a suports per a la immobilització d'enzims i un estudi de l'activitat i estabilitat dels enzims immobilitzades, 3) el desenvolupament de biosensors electroquímics per a detecció dels plaguicides abans esmentats basats en els elèctrodes modificats amb composites contenint enzims i CNOs. Aquesta tesi és, per tant, una contribució a un camp de ràpid creixement relacionat amb el desenvolupament de noves classes de nanomaterials de carboni que té com a objectiu ampliar les seves aplicacions actuals en la construcció de sistemes de detecció nous amb millors prestacions.<br>Actualmente existe una gran preocupación sobre el uso de pesticidas en la agricultura y sus posibles efectos secundarios. Esto hace que el desarrollo de sistemas de detección sensibles y robustos sea un paso importante en esta dirección. Por otro lado, las nano-cebollas de carbono (CNOs) son materiales muy atractivos y prometedores con estructuras definidas y propiedades electroquímicas notables que apenas se han estudiado en biosensores. El objetivo general de esta tesis es estudiar la interacción de diferentes plaguicidas con peroxidasa y tirosinasa con el objetivo de desarrollar biosensores para su detección basados ​​en electrodos modificados con CNOs. Para lograr este objetivo general, se ha estudiado: 1) la inhibición de las actividades de peroxidasa y tirosinasa por tres de los plaguicidas más utilizados (2,4-D, 2,4,5-T y glifosato), 2) el uso de CNOs oxidadas como soportes para la inmovilización de enzimas y un estudio de la actividad y estabilidad de las enzimas inmovilizadas, 3) el desarrollo de biosensores electroquímicos para detección de los plaguicidas antes citados basados ​​en los electrodos modificados con composites conteniendo enzimas y CNOs. Esta tesis es, por lo tanto, una contribución a un campo de rápido crecimiento relacionado con el desarrollo de nuevas clases de nanomateriales de carbono que tiene como objetivo ampliar sus aplicaciones actuales en la construcción de sistemas de detección novedosos con mejores prestaciones.<br>There is currently a strong concern on the use of pesticides in agriculture and their possible side effects. This makes the development of sensitive and robust detection systems an important step in this direction. On the other hand, carbon nano-onions are very attractive and promising materials with defined structures and remarkable electrochemical properties that have been scarcely studied in biosensing. The overall objective of this thesis is to study the interaction of different pesticides with peroxidase and tyrosinase with the aim to develop biosensors for pesticide detection based on CNO-modified electrodes. To achieve this general objective, the following aspects have been focused on: 1) the inhibition of peroxidase and tyrosinase activities by three of the most used pesticides (2,4-D, 2,4,5-T and glyphosate), 2) the use of oxidized CNOs as supports for the immobilization of enzymes and a study of the activity and stability of the immobilized enzymes, 3) the development of electrochemical biosensors for pesticide detection based on the prepared CNO-enzyme modified electrodes. This thesis is thus a contribution to a rapidly growing field related with the development of new classes of carbon nano-onion based nanomaterials that aims at expanding their current applications in the construction of novel detection systems with improved performances.

Incorporation of conductive carbon fillers into polymer matrices can improve electrical,thermal and mechanical properties of the resulting composites. In this work, three differentconductive carbon fillers were used; i.e. graphite, graphite nanoplatelets (GNP) and asreceivedmultiwall carbon nanotubes (A-MWCNT). In addition, A-MWCNT were modifiedusing mixed acids and named as T-MWCNT. These four fillers were incorporated into poly(ethylene terephthalate) (PET) to prepare four types of PET/carbon micro- and nanocomposites. These composites were prepared by melt compounding using a Haake Minilabextruder equipped with a co-rotating twin screws. The extruded samples were compressionmoulded to films of 1 mm thickness and were subsequently quenched to obtain lowcrystallinity samples. The extruded samples were also injection moulded to obtain dumbbellshaped specimens. The electrical, morphological, thermal and mechanical properties of thesecomposites were studied and characterized as a function of carbon filler types and contentsusing a wide range of analytical and testing techniques: namely; impedance spectroscopy,DSC, TGA, SEM, TEM, FTIR, DMTA and tensile testing. The results demonstrated that theaddition of graphite, GNP and A-MWCNT produced electrically conductive composites andthat the conductivities were found to be dependent on several factors; including filler type,filler content and processing conditions. The PET/A-MWCNT nanocomposites showed anexcellent electrical conductivity (~ 0.2 S/m at 2 wt. % A-MWCNT) with a low percolationthreshold (Fc ~ 0.33 wt. %). In contrast, PET/T-MWCNT nanocomposites displayed similarelectrical conductivity to that of pure PET and no percolation threshold was observed in thiscase (until 2 wt. % of CNT), this was attributed to the acid treatment which disrupted theinherent electrical conductivity of the CNT and also reduced their aspect ratio. However, TMWCNTshowed better dispersion and distribution into the PET matrix as well as reducedCNT-CNT interactions and therefore do not as readily form network structures. This resultedin better mechanical properties in comparison to the PET/A-MWCNT nanocomposites. Interms of processing, increasing screw speed during mixing was found to enhance theelectrical conductivities of PET/carbon nanocomposites (GNP and A-MWCNT), but onlyabove the percolation thresholds values, by ~ 2 – 3 orders of magnitude. However, nosignificant change was observed in the electrical conductivities of PET/graphitemicrocomposites. All the carbon fillers, with different dimensions, were found to act asnucleating agents for the PET matrix and hence accelerated crystallization and increased thedegree of crystallinity. CNT were found to accelerate the crystallization at lower loadingscompared to GNP and graphite. In addition, it was found that quenched PET and compositesamples were not fully crystallized after processing and therefore (cold) crystallized duringthe first heating cycle in both DSC and DMTA, as indicated by crystallisation peaks duringthe DSC first-heat and a rise in storage moduli above Tg during the DMTA first heat. Ingeneral, TGA showed that carbon fillers improved the resistance to thermal and thermooxidativedegradation under both air and nitrogen atmospheres. However, a reduction inthermal stability was observed for the composites containing T-MWCNT in air. The carbonfillers increased the storage and tensile moduli of the composites compared to pure PET.However; tensile strength and elongation at break were reduced except for compositecontaining T-MWCNT which showed no significant change at lower loadings. The tensile23moduli of nanocomposites were predicted using Halpin-Tsai models, which showed goodagreement at low loadings of A-MWCNT (≤ 0.2 wt. %) and GNP (≤ 2 wt. %). However,poor agreement was observed at higher loadings of fillers where the composites displayedreduced reinforcement efficiency. This correlates with results from SEM, which showedagglomeration, poorer distribution, debonding and rolling up of fillers in the PET matrix athigher loadings.

Thesis (Ph. D.)--Textile and Fiber Engineering, Georgia Institute of Technology, 2007.<br>Committee Chair: Kumar, Satish; Committee Member: Carr, Wallace; Committee Member: Graham, Samuel; Committee Member: Griffin, Anselm; Committee Member: Yao, Donggang.

Ordinary Portland cement (OPC) is the main constituent of concrete works as a principal binder for aggregates and intrinsically transmits the brittleness into concrete through the formation of hydration crystals in the cement microstructure. A number of nano cementitious composites were developed in recent years to offset the brittleness with newly discovered nanomaterials and the most prevalent among those is the graphene oxide (GO). The main objective of this PhD research work is to develop nano graphene cementitious composites (NGCC) using low cost, two dimensional (2D) graphene nanoplatelets (GNPs) and one dimensional (1D) graphited carbon nanofibres (GCNFs) with unique conical surface morphology. The GNPs were sourced synthesised in an environmental friendly way via plasma exfoliation whereas, GCNFs were manufactured through catalytic vapour grown method. The project further investigated the effect of these nanomaterials in regulating the distinctive microstructure of cement matrix leading to enhance its mechanical properties. Three different types of high-performance NGCC namely NGCC-Dot, NGCC-Fnt and NGCC-CNF, are developed by activating pristine GNPs (G-Dot), functionalised GNPs (G-Fnt) and graphited nanofibers (G-CNFs) into the cement matrix respectively. It is found through various characterization and experimental techniques that both GNPs and GCNFs regulated the cement microstructure and influenced the mechanical properties of NGCC uniquely. A remarkable increase in the flexural and the tensile strength of newly developed NGCC has been achieved and that could be attributed to the formation of distinctive microstructure regulated by catalytic activation of these nanomaterials. The shape (1D, 2D) and unique morphology of these nanomaterials played a vital role in the mechanism of crystal formation to regulate the cement microstructure. Based on the observations of test results and comprehensive characterization, the possible mechanisms of crystal formation and development of distinctive microstructure of NGCC has been established which has then proceeded to the development of a physical model for NGCC development.

Thesis (M.S.)--University of Cincinnati, 2008.<br>Advisor: Kumar Vemaganti. Title from electronic thesis title page (viewed Feb.25, 2009). Includes abstract. Keywords: carbon nano-composites; cohesive zone modeling (CZM); interface; finite element analysis. Includes bibliographical references.

Ce travail de thèse propose, par une approche multi-échelles, une compréhension de certains mécanismes de constitution des réseaux percolants de nanotubes de carbone initialement dispersés au sein de polymères thermoplastiques. L'impact du phénomène de « percolation dynamique » sur les propriétés électriques d.c. et a.c. des nanocomposites a ainsi été étudié par l'établissement d'inter-relations entre l'organisation des charges et les propriétés résultantes. L'effet de cette auto-organisation des systèmes sur les paramètres critiques d.c. de la loi de percolation statistique sont discutés. Des origines à la percolation dynamique sont proposées et permettent d'envisager de nombreuses applications industrielles. A titre d'exemple, le contrôle sur plusieurs ordres de grandeur de la permittivité et de la conductivité est proposé, certaines valeurs n'étant pas accessibles avec les méthodes conventionnelles<br>The present thesis proposes a multi-scale understanding of some mechanisms that govern the genesis of percolating networks constituted with carbon nanotubes in thermoplastic polymers. The effect of "dynamic percolation" on the d.c. and a.c. electrical properties of the resulting nanocomposites was studied by means of the identification of the relationships between the filler organization and the use properties. The consequences of this controlled self-organization on the statistic percolation law d.c. critical parameters are discussed. Two possible origins of the dynamic percolation are proposed. From an applicative point of view, thermal treatments were applied to design new materials. The range of accessible permittivity and conductivity values is also discussed

The many advances of nano technology extensively revolutionize mechanics. A tremendous need is growing to further bridge the gap between the classical mechanics and the nano scale for many applications at different engineering fields. For instance, the themes of interdisciplinary and multidisciplinary topics are getting more and more attention especially when the coherency is needed in diagnosing and treating terminal diseases or overcoming environmental threats. The fact that how mechanical, biomedical and electrical engineering can contribute to diagnosing and treating a tumor per se is both interesting and unveiling the necessity of further investments in these fields. This dissertation presents three different investigations in the area of nano mechanics and nano materials spanning from computational bioengineering to making mechanically more versatile composites. The first part of this dissertation presents a numerical approach to study the effects of the carbon nano tubes (CNTs) on the human body in general and their absorbability into the lipid cell membranes in particular. Single wall carbon nano tubes (SWCNTs) are the elaborate examples of nano materials that departed from mere mechanical applications to the biomedical applications such as drug delivery vehicles. Recently, experimental biology provided detailed insights of the SWCNTs interaction with live organs. However, due to the instrumental and technical limitations, there are still numerous concerns yet to be addressed. In such situation, utilizing numerical simulation is a viable alternative to the experimental practices. From this perspective, this dissertation reports a molecular dynamics (MD) study to provide better insights on the effect of the carbon nano tubes chiralities and aspect ratios on their interaction with a lipid bilayer membrane as well as their reciprocal effects with surface functionalizing. Single walled carbon nano tubes can be utilized to diffuse selectively on the targeted cell via surface functionalizing. Many experimental attempts have smeared polyethylene glycol (PEG) as a biocompatible surfactant to carbon nano tubes. The simulation results indicated that SWCNTs have different time-evolving mechanisms to internalize within the lipid membrane. These mechanisms comprise both penetration and endocytosis. Also, this study revealed effects of length and chirality and surface functionalizing on the penetrability of different nano tubes. The second part of the dissertation introduces a novel in situ method for qualitative and quantitative measurements of the negative stiffness of a single crystal utilizing nano mechanical characterization; nano indentation. The concept of negative stiffness was first introduced by metastable structures and later by materials with negative stiffness when embedded in a stiffer (positive stiffness) matrix. However, this is the first time a direct quantitative method is developed to measure the exact value of the negative stiffness for triglycine sulfate (TGS) crystals. With the advancements in the precise measuring devices and sensors, instrumented nano indentation became a reliable tool for measuring submicron properties of variety of materials ranging from single phase humongous materials to nano composites with heterogeneous microstructures. The developed approach in this chapter of the dissertation outlines how some modifications of the standard nano indentation tests can be utilized to measure the negative stiffness of a ferroelectric material at its Curie temperature. Finally, the last two chapters outline the possible improvements in the mechanical properties of conventional carbon fiber composites by introducing 1D nano fillers to them. Particularly, their viscoelastic and viscoplastic behavior are studied extensively and different modeling techniques are utilized. Conventional structural materials are being replaced with the fiber-reinforced plastics (FRPs) in many different applications such as civil structures or aerospace and car industries. This is mainly due to their high strength to weight ratio and relatively easy fabrication methods. However, these composites did not reach their full potential due to durability limitations. The majorities of these limitations stem from the polymeric matrix or the interface between the matrix and fibers where poor adhesion fails to carry the desired mechanical loadings. Among such failures are the time-induced deformations or delayed failures that can cause fatal disasters if not taken care of properly. Many methodologies are offered so far to improve the FRPs' resistance to this category of time-induced deformations and delayed failures. Several researchers tried to modify the chemical formulation of polymers coming up with stiffer and less viscous matrices. Others tried to modify the adhesion of the fibers to the matrix by adding different chemically functional groups onto the fibers' surface. A third approach tried to modify the fiber to matrix adhesion and at the same time improve the viscous properties of the matrix itself. This can be achieved by growing 1D nano fillers on the fibers so that one side is bonded to the fiber and the other side embedded in the matrix enhancing the matrix with less viscous deformability. It is shown that resistance to creep deformation and stress relaxation of laminated composites improved considerably in the presence of the nano fillers such as multiwall carbon nano tubes (MWCNTs) and zinc oxide nano wires (ZnO- NWs). The constitutive behaviors of these hybrid composites were investigated further through the use of the time temperatures superposition (TTS) principle for the linear viscoelastic behavior and utilizing phenomenological models for the viscoplastic behavior.<br>Ph. D.

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.

Carbon nanotubes, graphene and nano sized core shell rubber particles have all been extensively researched for their capability to improve mechanical properties of thermoset resins. However, there has been a lack of research on their evaluation for energy absorption in high velocity impact scenarios, and the fundamental mechanics of their failure mechanisms during highly dynamic stress transfer through the matrix. This fundamental research is essential for laying the foundation for improvement in ballistic performance in composite armor. In hard armor applications, energy absorption is largely accomplished through delamination between plies of the composite laminate. This energy absorption is accomplished through two mechanisms. The first being the elongation of the fiber reinforcement contained in the resin matrix, and the second is the propagation of the crack in between the discreet fabric plies. This research aims to fundamentally study the energy absorption characteristics of various nano-particles as reinforcements in thermoset resin for high velocity impact applications. Multiple morphologies will be evaluated through use of platelet, tubular and spherical shaped nano-particles. Evaluations of the effect on stress transfer through the matrix due to the combination of nano sized and micro scale particles of milled fiber is conducted. Three different nano-particles are utilized, specifically, multi-walled carbon nanotubes, graphene, and core shell rubber particles. The difference in surface area, aspect ratio and molecular structure between the tube, platelet and spherical nano-particles causes energy absorption through different failure mechanisms. This changes the impact performance of composite panels enhanced with the nano-particle fillers. Composite panels made through the use of dispersing the various nano-particles in a non-contact planetary mixer, are evaluated through various dynamic and static testing, including unnotched cantilever beam impact, mixed mode fracture toughness, split-Hopkinson bar, and ballistic V50 testing. The unnotched cantilever beam testing showed that the addition of milled fiber degraded the impact resistance of the samples. Addition of graphene nano platelets unilaterally degraded impact resistance through the unnotched cantilever beam testing. 1.5% loading of MWCNT showed the greatest increase in impact resistance, with a 43% increase over baseline. Determining the critical load for mixed mode interlaminar shear testing can be difficult for composite panels that bend without breaking. An iterative technique of optimizing the coefficient of determination, R2, in linear regression is developed for objectively determining the point of non-linearity for critical load. This allows for a mathematical method of determination; thereby eliminating any subjective decision of choosing where the data becomes non-linear. The core shell rubber nano particles showed the greatest strain energy release rate with an exponential improvement over the baseline results. Synergistic effects between nano and micro sized particles in the resin matrix during transfer of the stress wave were created and evaluated. Loadings of 1% milled carbon fiber enhanced the V50 ballistic performance of both carbon nanotube and core shell rubber particles in the resin matrix. However, the addition of milled carbon fiber degrades the impact resistance of all nano-particle enhanced resin matrices. Therefore, benefits gained from the addition of micro-sized particles in combination with nano-sized particles, are only seen in high energy impact scenarios with micro second durations. Loadings of 1% core shell rubber particles and 1% milled carbon fiber have an improvement of 8% in V50 ballistic performance over the baseline epoxy sample for 44 mag single wad cutter gas check projectiles. Loadings of 1% multi-walled carbon nanotubes with 1% milled carbon fiber have an improvement of 7.3% in V50 ballistic performance over the baseline epoxy sample. The failure mechanism of the various nano-particle enhanced resin matrices during the ballistic event is discussed through the use of scanning electron microscope images and Raman spectroscopy of the panels after failure. The Raman spectroscopy data shows a Raman shift for the fibers that had an enhancement in the V50 performance through the use of nano-particles. The Raman band for Kevlar centered at 1,649 cm-1 stemming from the stretching of the C==O bond of the fiber shows to be more sensitive to the residual axial strain, while the Raman band centered at 1,611 cm-1 stemming from the C-C phenyl ring is minimally affected for the CSR enhanced panels due to the failure mechanism of the CSR particles during crack propagation.<br>Ph.D.<br>Doctorate<br>Mechanical and Aerospace Engineering<br>Engineering and Computer Science<br>Mechanical Engineering

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 2013<br>Newly 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..

It was found that a significant improvement of mechanical properties of CFRPs can be achieved by the adjustment of the matrix properties such as toughness and CF/matrix adhesion via the chemical modification, as well as the physical modification by a small amount of cheap and environment-friendly nano fibers. Based on investigation of fracture mechanisms at macro/micro scale, the effects of matrix properties and nano fiber on the mechanical properties of CFRP have been discussed. Subsequently, the relationship has been characterized by a numerical model to show how to modulate the parameters of the matrix properties to achieve excellent fatigue properties of CFRP.<br>博士(工学)<br>Doctor of Philosophy in Engineering<br>同志社大学<br>Doshisha University

Made available in DSpace on 2014-06-11T19:25:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-18Bitstream added on 2014-06-13T18:53:40Z : No. of bitstreams: 1 rebeque_pvs_me_ilha.pdf: 2184375 bytes, checksum: 85d1dba31d0aecfc00a6316b5737526f (MD5)<br>Compósitos poliméricos condutores, também chamados de polímeros condutores extrínsecos, têm sido alvo de intensa pesquisa científica devido ao seu grande potencial de aplicação nos mais diversificados setores industriais. Esses materiais combinam as características de um polímero (leveza, flexibilidade, fácil processamento) com as de cargas condutoras (alta condutividade). O poliuretano derivado de óleo de mamona (PUR) é um polímero obtido pela mistura de pré-polímero e poliol (derivado de óleo de mamona) que apresenta grande potencial para ser utilizado como matriz polimérica em compósitos. Ele possui propriedades equivalentes aos dos poliuretanos (PU) convencionais e tem como vantagem ser um polímero biodegradável e proveniente de fonte renovável. Em relação às cargas condutoras, o negro de fumo (NF) é um dos materiais mais utilizados para esse fim, enquanto que pouco se encontra na literatura sobre o carvão ativado nano em pó (CANP), mesmo possuindo estrutura semelhante e maior condutividade que o NF. Neste contexto, o presente trabalho tem como objetivo viabilizar os processos de síntese e fazer a caracterização elétrica dos compósitos poliuretano derivado de óleo de mamona/carvão ativado nano em pó (PUR/CANP) e poliuretano derivado de óleo de mamona/negro de fumo (PUR/NF) na forma de filmes pelo método “casting”, mantendo fixa a razão pré-polímero/poliol e variando a fração de volume de CANP e NF. A análise térmica foi feita por Calorimetria Diferencial de Varredura (DSC), o estudo da condutividade dc e ac foram feitas pelo Método de Duas Pontas (tensão x corrente) (MDP) e pela técnica de Espectroscopia de Impedância Elétrica (EIE), respectivamente, e a análise morfológica foi feita em Microscópio Eletrônico de Varredura com canhão de elétrons por...<br>Conductive polymer composites, also called extrinsic conducting polymers, has been the subject of intense scientific research due to its great potential for industrial application. These materials combine the characteristics of a polymer (lightness, flexibility, easy processing) with the conductive fillers (high conductivity). The castor oil based polyurethane (PUR) is a polymer obtained from pre-polymer and polyol (based castor oil) mixing which has great potential to be used as matrix polymer in composites. It has properties equivalent to those of conventional polyurethane (PU) and has the advantage of being a biodegradable polymer and from a renewable source. In relation to conductive fillers, carbon black (CB) is one of the most widely used materials for this purpose, while in the literature there are few data about activated carbon nanopowder (ACNP), despite having similar structure and that the higher conductivity than CB. In this context, this work aims to provide the synthesis processes and electrically characterize of composite castor oil based polyurethane/activated carbon nanopowder (PUR/ACNP) and castor oil based polyurethane/carbon black (PUR/CB) in the form of films by casting, keeping the ratio pré-polímero/poliol fixed and varying the volume fraction ACNP and CB. The sample were characterized using Differential Scanning Calorimetry (DSC), Two Points Method (voltage x current) (TPM), Electrical Impedance Spectroscopy (EIS) and Scanning Electron Microscope with electron gun for field emission (FEG-SEM). DSC results showed that the glass transition temperature (Tg) of composites do not depend of type or volume fraction of conductive fillers. The results of electrical analysis showed that the samples of PUR/CB have lower percolation threshold than those of PUR/ACNP (20% vs. 40%). This result is due the distribution... (Summary complete electronic access click below)

Isolante. On a étudié les processus de formation d'une structure ségrégée, qui conduisait à la formation d'une distribution ordonnée de particules dans une matrice polymère. Il est montré que dans le système ségrégé, la valeur du seuil de percolation φc est d'un ordre de grandeur inférieur à celui d'un composite présentant une distribution aléatoire des charge (2,95% vol. pour le composite ségrégé contre 24,8% vol. pour le composite à distribution aléatoire). Le seuil de percolation dans le cas d'un mélange de charges est très inférieur à la valeur calculée à l'aide de la règle des mélanges. Il est montré que les résultats expérimentaux de conductivité thermique ne révèlent pas de comportement de percolation et peuvent être décrits de façon satisfaisante par le modèle de Lichtenecker. La valeur du paramètre λf traduisant la conductivité thermique de la charge en tenant compte de l’interface charge/matrice est de 4,4 fois plus élevé pour les systèmes ségrégés que pour un composite à distribution aléatoire de particules. Il est montré que dans les systèmes ségrégés, les paramètres de blindage sont considérablement augmentés en raison de l'absorption provoquée par la réflexion interne sur les parois conductrices du réseau de charges conductrices. Il est établi que les charges de carbone constituent la base la plus efficace, ce qui garantit une absorption élevée des rayonnements électromagnétiques (REM) aux faibles concentrations. Il est avéré que le plus grand effet de blindage est observé pour un mélange de charges hybrides GNP/CNT (nanoplaques en graphite / nanotubes de carbone). L'effet de synergie s'explique par la meilleure interaction du REM avec le réseau hybride ramifiée formés par les charges, ce qui entraîne une absorption accrue du REM. Les systèmes à structure ségrégée à base d'élastomères présentent un effet piézorésistif prononcé avec une relation linéaire de déformation / modification de l'intensité du courant. L'étude de l'effet piézorésistif dans une large gamme de température (-40 / +50°С) a montré la stabilité des caractéristiques principales et la possibilité d'utiliser le composite dans une large gamme de températures<br>The thesis determines the principles of the conductive phase structure formation in polymer composites containing conductive fillers, which will be different types of carbon fillers. The processes of segregated structure formation in which the particles of the filler are localized on the surfaces of polymer grains is studied. It is shown that the value of the percolation threshold φc for the segregated system is one order lower than in the composite with a random distribution of the filler 2.95 vol.% and 24.8 vol.%, respectively. The hybrid filler shows percolation threshold, much lower than the value calculated using the mixing rule. Experimental results of thermal conductivity for systems filled with anthracite, graphene and hybrid filler Gr/A do not reveal percolation behaviour and can be well described by the Lichtenecker model. It is shown that λf for segregated systems is 4.4 times higher than for a composite with a random distribution of filler particles. It is shown that in segregated systems the shielding parameters are significantly increased due to the absorption caused by the internal reflection on the conductive walls of the filler framework. Carbon fillers create the most effective basis that ensures a high absorption rate of EMI at low concentrations. It was found that the greatest shielding effect in the interaction of a composite with electromagnetic radiation was observed for the hybrid filler GNP/CNT (graphite nanoplatelets/carbon nanotubes). The synergistic effect is explained not by their higher electrical conductivity, but by the better interaction of the EMI with the developed hybrid framework of the filler, which causes increased absorption of the EMI. Systems with a segregated structure based on elastomer (ground rubber) with a polymer-adhesive and hybrid electroconductive nano-fillers exhibit a significant piezoresistive effect. The cyclic studies of electric response, depending on the applied external load, showed a linear relationship between composite deformation and current changes through the sample and demonstrate stable long-term stability. The study of the piezoresistive effect in a wide temperature range (-40 ÷ +50°C) showed the stability of the main characteristics and the possibility of exploiting the composite in a wide temperature range

L’utilisation des nanotubes de carbone (CNT) dans les cellules photovoltaïques (PV) se limitent à leur application comme électrodes ou comme dopant dans la couche active à cause de leur conductivité extrêmement élevée provocant des courts-circuits au sein de la cellule. Dans le cadre de cette thèse, nous avons proposé et validé un nouveau concept consistant à développer les SWNT comme matériaux actifs accepteurs alternatifs au PCBM (dérivé de fullerène) pour le photovoltaïque organique.Nous avons développé une voie de synthèse chimique basée sur la fonctionnalisation contrôlée des SWNT et la quantification de leur degré de fonctionnalisation. Ce nouveau concept permettra l’élaboration des SWNT « sur mesure » avec des conductivités et des propriétés optiques et électrochimiques modulables et adéquats avec les propriétés requise pour une intégration dans les dispositifs photovoltaïques en hétérojonctions avec les polymères pi-conjugués donneurs commerciaux.Il a été mis en évidence grâce aux caractérisations des propriétés finales des SWNT synthétisés que la conductivité, l’absorption dans l’UV-visible et les propriétés électrochimiques évoluent graduellement selon deux modes en fonction du degré de fonctionnalisation. De plus, la fonctionnalisation contrôlée des SWNT induit un effet dispersant permettant de faciliter leur intégration dans les dispositifs PV en utilisant les technologies de mise en œuvre par voie solvant existantes comme l’impression par jet d’encre ou roll-to-roll l’élaboration des couches minces par voie solvant. La preuve de ce concept a été validée grâce aux tests en cellules PV avec un polymère standard commercial P3HT et un polymère à faible gap optique synthétisé<br>Controlled modulation of intrinsic functional (absorption, band gap, conductivity) and physico-chemical properties (dispersability, solvent-processability) of CNTs could broaden up their application potential in nanotechnology. However, it has been an ambitious synthetic goal for more than a decade. In this work, we developed an efficient methodology to do so in a mastered manner on single-walled carbon nanotubes (SWNT). It involves the meticulous functionalization based on gradual formation of covalent aryl bonds. It was proven that, the intrinsic electrical conductivity, optical and electrochemical properties of the functionalized SWNTs could be gradually modulated in two steps depending on the functionalization degree. The so- controlled covalent functionalization was the basic synthetic technique to make SWNT easier to manipulate and tolerably soluble, with modulated electrical and electrochemical properties, so that the performances in photovoltaic cells were unusually appreciated. Unsorted functionalized SWNTs were employed in organic photovoltaic (OPV) cells as electron acceptors or dopants with commercial polymer (P3HT) and novel, synthesized low bandgap copolymer, respectively

Cette thèse porte sur la mise en œuvre, la caractérisation microstructurale et l'étude des propriétés macroscopiques de matériaux nanocomposites à matrice polymère (un latex filmogène) renforcée par des nanofibres flexibles à haut facteur de forme. En étudiant deux types de renforts (les nanotubes de carbone et les nanofibrilles de cellulose) et en utilisant deux procédés différents pour l'élaboration des composites, ce travail a permis de mieux comprendre le rôle que jouent les enchevêtrements entre nanofibres et la nature de leurs interactions dans ce type de matériaux. Les propriétés mécaniques aux faibles et grandes déformations, et, dans le cas des renforts nanotubes de carbone, les propriétés élecriques ont été analysées. Une approche de modélisation basée sur la discrétisation des fibres dans un volume représentatif, a permis de discuter l'influence de la tortuosité des fibres et des propriétés électriques des contacts entre fibres sur la percolation électrique.

Hydroxyapatite (HA) has received wide attention in orthopedics, due to its biocompatibility and osseointegration ability. Despite these advantages, the brittle nature and low fracture toughness of HA often results in rapid wear and premature fracture of implant. Hence, there is a need to improve the fracture toughness and wear resistance of HA without compromising its biocompatibility. The aim of the current research is to explore the potential of nanotubes as reinforcement to HA for orthopedic implants. HA- 4 wt.% carbon nanotube (CNT) composites and coatings are synthesized by spark plasma sintering and plasma spraying respectively, and investigated for their mechanical, tribological and biological behavior. CNT reinforcement improves the fracture toughness (>90%) and wear resistance (>66%) of HA for coating and free standing composites. CNTs have demonstrated a positive influence on the proliferation, differentiation and matrix mineralization activities of osteoblasts, during in-vitro biocompatibility studies. In-vivo exposure of HA-CNT coated titanium implant in animal model (rat) shows excellent histocompatibility and neobone integration on the implant surface. The improved osseointegration due to presence of CNTs in HA is quantified by the adhesion strength measurement of single osteoblast using nano-scratch technique. Considering the ongoing debate about cytotoxicity of CNTs in the literature, the present study also suggests boron nitride nanotube (BNNT) as an alternative reinforcement. BNNT with the similar elastic modulus and strength as CNT, were added to HA. The resulting composite having 4 wt.% BNNTs improved the fracture toughness (~85%) and wear resistance (~75%) of HA in the similar range as HA-CNT composites. BNNTs were found to be non-cytotoxic for osteoblasts and macrophages. In-vitro evaluation shows positive role of BNNT in osteoblast proliferation and viability. Apatite formability of BNNT surface in ~4 days establishes its osseointegration ability.

Hybrides nano /micrométriques de nanotubes de carbone (NTC) greffés sur microparticules d'alumina, microplaques de SiC ou nanoplaquettes de graphène (NPG) ont été utilisés comme renforts multifonctionnelles dans les composites à matrice polymère. Le NTCs utilisés étaient généralement sous forme de six branches symétriques et orthogonales sur microparticules sphériques d'Al2O3, mais d'une ou deux branches alignées verticalement sur les deux côtés de microplaques de SiC et de NPG. L'introduction des structures hybrides dans une matrice époxy permet d'améliorer la dispersion des NTC et l'interaction interfaciale entre les renforts et la matrice. Les propriétés mécaniques des composites ont été fortement améliorées avec une faible concentration de hybrides. La résistance électrique in situ des composites a atteint d'abord à sa valeur maximale et puis diminue avec la présence d'une déformation irréversible. Ce phénomène observé est complètement différent par rapport à ce des composites renforcé par NTC, c'est-à-dire, une augmentation monotone de la résistance jusqu'à leur rupture final. Les propriétés mécaniques et les comportements de self-sensing des composites dependent fortement de l'élancement de NTC de leur organisation et aussi des substrats. L'introduction des hybrides dans les composites renforcés par des fibres longues (verre) a démontré un grand potentiel pour développer des composites multi-échelles. Les études réalisées sur la matrice époxy renforcée par les hybrides bien dispersés avec une faible fraction ont montré des améliorations importantes des propriétés de flexion à 3 points et des propriétés thermo-mécaniques. Les réseaux conducteurs formés par hybrides nano/micrométriques permettent de suivre in situ l'évolution de l'état de dégradation des composites à matrice époxy renforcés par des tissus de verre sous contrainte appliquée.

La dispersion des nanotubes de carbone (NTC) dans le polyfluorure de vinylidène (PVDF) est un grand défi pour avoir de meilleures propriétés diélectriques. Les hybrides, titanate de baryum (BT)-NTC, ayant une structure particulière sont révélés être efficaces pour l'amélioration de la dispersion de NTC dans la matrice de polymère et la réduction du seuil de percolation du matériau composite. Cette thèse vise à atteindre une haute performance diélectrique du composite via la conception de charges ayant une structure favorable ainsi que l'étude exhaustive de l'interaction entre les NTC et la matrice de polymère semi-cristallin.Dans le chapitre 1, un bref revu de l'état de l'art sur le contexte général des matériaux diélectrique est introduite ainsi les progrès récents dans ce domaine sont présentés pour mieux comprendre les composites et leurs application.Dans le chapitre 2, nous préparons deux types d'hybrides avec deux structures différentes. Les premiers hybrides sont préparés par un dépôt chimique en phase vapeur (CVD). Les BT forment le noyau de ces hybrides et les NTC croient dessus (H-NTC-BT). Les deuxième hybrides sont préparées par réaction hydrothermale où NTC sont revêtus par les BT (H-BT-NTC). Par la suite, nous préparons des composites avec une matrice de PVDF renforcés par les deux types d'hybrides déjà synthétisés cela en coulant la solution puis par extrusion-injection. En outre, les méthodes de caractérisation de la morphologie, des propriétés thermiques, diélectriques et la cristallisation sont également introduites dans ce chapitre.Dans le chapitre 3, les comportements diélectriques de H-NTC-BT/PVDF sont étudiés en détails. Une augmentation dramatique de la permittivité diélectrique est observée après le traitement thermique. Ce changement peut être dû à la réorganisation du réseau conducteur de NTC et la recristallisation de PVDF. Par la modélisation et la caractérisation expérimentale, Nous déduisons que cette augmentation significative de la permittivité diélectrique après le traitement thermique est dû au rétrécissement de la distance de NTC dans des couches amorphes voisine de PVDF d'un côte et au polymorphe β à l'interface NTC-PVDF d'un autre.Dans le chapitre 4, la dispersion des NTC dans la matrice du composite PVDF est étudiée par la conception de différentes structures. Tout d'abord, une comparaison du seuil de percolation de H-NTC-BT/PVDF calculé et celui déterminé expérimentalement est menée pour mieux comprendre la morphologie de H-NTC-BT. Ensuite, deux comparaisons sont menées:- La première compare les facteurs de transformation de la dispersion des NTC dans les composites H-NTC-BT/PVDF et NTC/PVDF cela en mesurant de la conductivité AC dans les différentes couches de ces composites.- La deuxième compare trois types de composites de PVDF renforcés par des hybrides ayant la même fraction volumique de NTC et BT mais des structures différentes. L'effet de ces différentes structures de ces hybrides est étudié en comparant leurs propriétés diélectriques.Pour finir une conclusion générale est présentée dans le chapitre 5 ainsi les perspectives prévues pour les travaux futurs<br>The dispersibility of carbon nanotube (CNT) in polyvinylidene fluoride (PVDF) is always a big challenge for the high dielectric property. Barium titanate (BT)-CNT hybrids with the special structure are proved to be effective for improving the dispersion of CNT in the polymer matrix and reduce the percolation threshold of the composite. This thesis aims to achieve high dielectric performance of composites via designing fillers with the favorable structure as well as comprehensively study the interaction between CNT and semi-crystalline polymer matrix.In chapter 1, we provide a general introduction about dielectric material's background knowledge. Meanwhile the development including recent breakthroughs and their applications for the dielectric field are also provided in this chapter.In chapter 2, we prepare two hybrids with different structures. The first hybrids are prepared by chemical vapor deposition (CVD) method. It is with the structure of BT as a core and CNTs growing outsides (H-CNT-BT). The second hybrids are prepared by hydrothermal reaction where BT particles coats outside CNT (H-BT-CNT). Meanwhile, we fabricate hybrids reinforced PVDF matrix composites by solution casting plus extrusion-injection way. Additionally, methods for characterization involving morphology, thermal and dielectric properties as well as crystallization are also introduced in this chapter.In chapter 3, the dielectric behaviors of H-CNT-BT/PVDF are studied concretely. A dramatic increment on dielectric permittivity is observed after the thermal treatment. This change may result from the reformation of CNT's conductive network and the behavior of PVDF's re-crystallization. By modeling work and experimental characterization, the shrinkage of the neighboring CNT's distance in PVDF's amorphous layers and the induced β polymorph at the CNT-PVDF interface may cause the significant increment in dielectric permittivity after the thermal treatment.In chapter 4, the CNT's dispersibility in PVDF matrix composites is studied by designing different structures. Firstly, a comparison between calculated and experimental percolation threshold of H-CNT-BT/PVDF is conducted for studying the morphology parameters of H-CNT-BT. Afterwards, two comparisons are conducted: one is between H-CNT-BT/PVDF and CNT/PVDF. The processing factors for the CNT's dispersibility are discussed via measuring the different layer's AC conductivity. The other is among three hybrids reinforced PVDF composites. The hybrids structure's effect the CNT's dispersibility is discussed via comparing the dielectric property of the composites with the same volume fraction of CNT and BT but different structures.In chapter 5, a general conclusion is formed according to the works and the perspective is provided for the improvement of the future work

Cette étude porte sur l'influence des nano-charges conductrices de noir de carbone sur le comportement mécanique de matériaux composites, dans le but d'intégrer la fonction du blindage électromagnétique. Ces travaux ont traité, dans un premier temps, du problème pratique de la réalisation d'un tel composite et notamment, de la diffusion de la résine chargée lors de la mise en oeuvre par des procédés classiques par voie liquide (Infusion et RTM-Eco). La Première phase du travail est réalisé sur la résine chargée seule, dans le but de comprendre l'impact des nano-charges conductrices sur le comportement mécanique d'une résine thermodurcissable de type vinylester avant l'injection de cette résine dans la préforme. Finalement une partie est consacrée à la caractérisation de composite à résine nanochargée en termes d'efficacité de blindage électromagnétique dans une gamme de fréquence allant de 10 MHz à 6 GHz.

La découverte des nanotubes de carbone (NTCs) par S. Iijima en 1990 a permis d'explorer un nouveau monde à l'échelle nanométrique. Les études sur la synthèse des NTCs durant le début de cette décennie ont apporté une reproductibilité des formes allotropiques de carbone. Les propriétés mécaniques et électriques exceptionnelles des NTCs ont éveillé l'esprit des scientifiques afin de concevoir des systèmes touchant le domaine de la nanotechnologie. Dans ce contexte, mes travaux de recherches ont visé à étudier les potentialités des nanotubes de carbone dans le domaine des hyperfréquences. Deux types d'applications peuvent être distinguées : l'élaboration de matériau nano-composite mais aussi la miniaturisation des composants électromécaniques (NEMS). L'application la plus immédiate des NTCs consiste à les utiliser comme additif dans des polymères, thermoplastiques, thermodurcissables ou élastomères, afin d'en modifier les propriétés. L'utilisation des matériaux composites à base de nanotubes de carbone apparaît comme une voie prometteuse dans le domaine des nanotechnologies grâce à leurs propriétés structurales et électroniques très particulières. Pour élargir le domaine d'application des NTCs, nous avons étudié un nouveau matériau composite à base d'un polymère (BenzoCycloButène ''BCB'') et de nanotubes de carbone double parois (DNTCs) pour une utilisation aux fréquences micro-ondes. Nous rapportons ici une étude des propriétés micro-ondes de composites BCB/DNTCs en fonction de la concentration massique de nanotubes. Nous présentons, dans un premier temps, les méthodes d'homogénéisation et de fabrication du composite, puis nous traitons l'élaboration de structures de test adaptées à des mesures µondes et millimétriques. Après caractérisation, nous donnons le comportement spectral et la modélisation pour les pertes linéiques ainsi que e* (permittivité effective complexe). Cette étude a permis de montrer qu'il est possible de configurer les performances électriques d'un matériau composite en fonction du % de NTCs incorporés. .<br>The discovery of carbon nanotubes (NTCs) by S. Iijima in 1990 allowed to explore a new world at the nanoscale. At the beginning of this decade, studies have provided a reproducibility of carbon nanotubes. Carbon nanotubes have shown exceptional stiffness, strength and remarkable thermal and electrical properties, which make them ideal candidates for the development of multifunctional materials systems. My research presents two possible uses of carbon nanotubes (CNTs) for microwave applications, exploiting their exceptional electrical and mechanical properties. The first one consist in utilizing their metallic or semiconducting properties to modify the electrical behavior of polymer (BCB) doped with carbon nanotubes. The second one aims to extend the concept of passive and reconfigurable micrometer components (MEMS)at the nanoscale to develop Nano-Electro-Mechanics Systems (NEMS). The first study consisted of an electromagnetic characterisation of polymer BenzoCycloButen (BCB) composites containing dispersed CNTs at microwave frequencies (40MHz - 40GHz) using coplanar waveguides (CPW). A new nano-composite material based on carbon nanotubes and BCB polymer is studied for shielding and electromagnetic wave absorption. For the first time to our knowledge, methods of homogenization and composite fabrication are presented, next test structures to measure microwave parameters are developed. After characterization, linear attenuation "a", complex permittivity "e*", conductivity "s" and power absorption "PA" are extracted and compared to simulation results obtained using the electromagnetic field simulator "HFSS". The electrical parameters of nano-composites are modified by DWCNTs concentration. The percolation threshold is obtained with only 0. 075wt. % of DWCNTs in BCB and the nano-composites showed 5dB of PA at 30GHz. The resulting engineerable composite gives RF-designer one more degree of freedom to to develop and optimize microwave components. .

Cilj&nbsp; ove&nbsp; doktorske&nbsp; disertacije&nbsp; je&nbsp; bio&nbsp; razvoj&nbsp; brzih&nbsp; i&nbsp; pouzdanih&nbsp; voltametrijskih&nbsp; metoda zasnovanih na primeni jednostavnih i savremenih elektroda/senzora na bazi ugljeničnih materijala (ugljenične&nbsp; paste&nbsp; napravljene&nbsp; od&nbsp; grafitnog&nbsp; praha&nbsp; i&nbsp; parafinskog&nbsp; ulja&nbsp; i&nbsp; &scaron;tampanih&nbsp; ugljeničnih elektroda)&nbsp; za&nbsp; određivanje&nbsp; H ₂O₂u&nbsp; odabranim&nbsp; složenim&nbsp; model&nbsp; i&nbsp; realnim&nbsp; uzorcima.&nbsp; U&nbsp; tu&nbsp; svrhu, ispitana je primenljivost različitih radnih elektroda. Amperometrijska&nbsp; metoda&nbsp; zasnovana&nbsp; na&nbsp; elektrodi&nbsp; od&nbsp; ugljenične&nbsp; paste&nbsp; (CPE)&nbsp; zapreminski modifikovane&nbsp; sa&nbsp; 5%&nbsp; (m:m)&nbsp; MnO2 je,&nbsp; pri&nbsp; optimizovanim&nbsp; uslovima&nbsp; i&nbsp; pri&nbsp; radnom&nbsp; potencijalu&nbsp; od 0,40 V&nbsp; u&nbsp; odnosu&nbsp; na&nbsp; zasićenu&nbsp; kalomelovu&nbsp; elektrodu&nbsp; (ZKE)&nbsp; u&nbsp; fosfatnom&nbsp; puferu&nbsp; pH&nbsp; 7,50&nbsp; kao pomoćnom elektrolitu, omogućila kvantifikaciju H ₂O₂ u opsegu koncentracija od 1,4 do 65 &micro;g mL -1 sa&nbsp; relativnom&nbsp; standardnom&nbsp; devijacijom&nbsp; (RSD)&nbsp; manjom&nbsp; od&nbsp; 10%.&nbsp; Ova&nbsp; metoda&nbsp; je&nbsp; primenjena&nbsp; za određivanje sadržaja H ₂O₂u uzorcima podzemne vode iz centralnog Banata (Pokrajina Vojvodina, Srbija)&nbsp; tretirane&nbsp; Fentonovim&nbsp; (Fe²⁺ i&nbsp; H ₂O₂ )&nbsp; i&nbsp; Fentonu-sličnim&nbsp; (Fe ³⁺ i&nbsp; H ₂O₂ )&nbsp; reagensima&nbsp; u&nbsp; cilju uklanjanja&nbsp; prirodnih&nbsp; organskih&nbsp; materija&nbsp; (POM)&nbsp; pri&nbsp; čemu&nbsp; su&nbsp; kori&scaron;ćene&nbsp; različite&nbsp; početne koncentracije&nbsp; gvožđa&nbsp; i&nbsp; različiti&nbsp; odnosi&nbsp; molarnih&nbsp; koncentracija&nbsp; gvožđa&nbsp; i&nbsp; H ₂O₂ .&nbsp; Utvrđeno&nbsp; je&nbsp; da oksidaciono&nbsp; stanje&nbsp; gvožđe&nbsp; (Fe²⁺ ili&nbsp; Fe ³⁺)&nbsp; i&nbsp; molarni&nbsp; odnos&nbsp; jona&nbsp; Fe&nbsp; i&nbsp; H₂O₂ utiču&nbsp; na&nbsp; stepen potro&scaron;nje/razgradnje&nbsp; H₂O₂u&nbsp; podzemnoj&nbsp; vodi&nbsp; sa&nbsp; visokim&nbsp; sadržajem&nbsp; POM.&nbsp; Takođe,&nbsp; u&nbsp; slučaju Fentonu-sličnog&nbsp; procesa,&nbsp; za&nbsp; sve&nbsp; početne&nbsp; koncentracije&nbsp; Fe ³⁺ i&nbsp; H ₂O_{2 ,}&nbsp; signifikantna&nbsp; količina&nbsp; H ₂O₂ostaje&nbsp; neiskori&scaron;ćena,&nbsp; &scaron;to&nbsp; ukazuje&nbsp; na&nbsp; nižu&nbsp; efikasnost&nbsp; ovakvog&nbsp; sistema u&nbsp; poređenju&nbsp; sa&nbsp; Fentonovim procesom.&Scaron;tampana&nbsp; ugljenična&nbsp; elektroda&nbsp; (SPCE)&nbsp; zapreminski&nbsp; modifikovana&nbsp; sa&nbsp; MnO 2 kao medijatorom&nbsp; je&nbsp; primenjena&nbsp; za&nbsp; određivanje&nbsp; sadržaja&nbsp; H₂O₂ u&nbsp; toku&nbsp; Fentonovog&nbsp; (Fe ²⁺ ,&nbsp; H₂O₂ )&nbsp; i vidljivom&nbsp; svetlo&scaron;ću&nbsp; potpomognutog&nbsp; foto-Fentonovog&nbsp; (Fe²⁺,&nbsp; H ₂O₂,&nbsp; h&nu;)&nbsp; procesa&nbsp; uklanjanja neonikotinoidnog&nbsp; insekticida&nbsp; acetamiprida&nbsp; (ACT).&nbsp; Pri&nbsp; optimizovanim&nbsp; uslovima&nbsp; (radni&nbsp; potencijal 0,40&nbsp; V&nbsp; u&nbsp; odnosu&nbsp; na&nbsp; ZKE,&nbsp; fosfatni&nbsp; pufer&nbsp; pH&nbsp; 7,50&nbsp; kao&nbsp; pomoćni&nbsp; elektrolit)&nbsp; amperometrijskog određivanja&nbsp; H ₂O₂ ,&nbsp; postignuta&nbsp; je&nbsp; linearnost&nbsp; u&nbsp; opsegu&nbsp; koncentracija&nbsp; 0,01&ndash;1,24&nbsp; mmol&nbsp; L-1(0,34&ndash; 42,2 &micro;g mL -1) i vrednost RSD nije prelazila 4,2%. U ispitivanimuzorcima (nakon odgovarajućegpode&scaron;avanja pH vrednosti od 2,8 do 7,5 odmah nakon&nbsp; uzorkovanja radi stopiranja ili maksimalnog usporavanja&nbsp; procesa&nbsp; oksidacije,&nbsp; filtriranja,&nbsp; zamrzavanja&nbsp; i&nbsp; odmrzavanja&nbsp; neposredno&nbsp; pre&nbsp; merenja) sadržaj&nbsp; H ₂O₂ je&nbsp; određen&nbsp; metodom&nbsp; standardnog&nbsp; dodatka&nbsp; analiziranjem&nbsp; odgovarajućih amperometrijskih&nbsp; krivi.&nbsp; Paralelna&nbsp; HPLC-DAD&nbsp; merenja&nbsp; su&nbsp; vr&scaron;ena&nbsp; u&nbsp; cilju&nbsp; praćenja koncentracije/uklanjanja ACT. U slučaju foto-Fentonovog procesa (početne koncentracije 0,31; 2,0 i 3,0 mmol L -1 (70,0; 111,7 i 102,1 &micro;g mL -1 ) za ACT, Fe²⁺ i H ₂O₂, redom) nakon 10 min H ₂O₂je izreagovao, a može se smatrati da je ACT uklonjen nakon 5 min. U toku Fentonovog procesa ACT je&nbsp; uklonjen&nbsp; nakon&nbsp; 20&nbsp; min&nbsp; tretmana&nbsp; i&nbsp; oko&nbsp; 10%&nbsp; početne&nbsp; koncentracije&nbsp; H ₂O₂ je&nbsp; ostalo&nbsp; u&nbsp; sistemuneiskori&scaron;ćeno.CPE&nbsp; je&nbsp; povr&scaron;inski&nbsp; modifikovane&nbsp; kompozitom&nbsp; na&nbsp; bazi&nbsp; nanočestica&nbsp; Pt&nbsp; (&lt;&nbsp; 5&nbsp; nm)&nbsp; i grafitizovanog&nbsp; ugljenika&nbsp; (Pt-C,&nbsp; 10%&nbsp; Pt&nbsp; na&nbsp; Vulkanu&nbsp; XC72)&nbsp;&nbsp; etodom&nbsp; nano&scaron;enja&nbsp; kapi. Nemodifikovana&nbsp; CPE&nbsp; i&nbsp; modifikovana&nbsp; (Pt-C/CPE)&nbsp; su&nbsp;&nbsp; okarakterisane&nbsp; primenom&nbsp; SEM/EDS&nbsp; i&nbsp; CV merenja.&nbsp; Pt-C/CPE&nbsp; je&nbsp; pokazala&nbsp; izuzetne&nbsp; elektrokatalitičke&nbsp; osobine&nbsp; u&nbsp; pogledu&nbsp; elektrohemijskeredoks&nbsp; reakcije&nbsp; H₂O₂ u&nbsp; poređenju&nbsp; sa&nbsp; nemodifikovanom&nbsp; CPE&nbsp; u&nbsp; fosfatnom&nbsp; puferu&nbsp; (0,1 mol&nbsp; L -1 ;pH 7,50),&nbsp; a&nbsp; takođe&nbsp; i&nbsp; u&nbsp; acetatnom&nbsp; puferu&nbsp; (0,1&nbsp; mol&nbsp; L -1 ;&nbsp; pH&nbsp; 4,50)&nbsp; kao&nbsp;&nbsp; pomoćnim&nbsp; elektrolitima. Prilikom&nbsp; amperometrijskog&nbsp; određivanja&nbsp; H ₂O₂ primenom&nbsp; Pt-C/CPE&nbsp; u&nbsp; model&nbsp; sistemima, zadovoljavajuća linearnost je postignuta u koncentracionom opseguH₂O₂od 0,15 do 1,45 &micro;g mL -1 ,dok su vrednosti GO iznosile 0,06 &micro;g mL -1 (pH 7,50, radni potencijal 0,20 V) i 0,10 &micro;g mL -1 (pH4,50,&nbsp; radni&nbsp; potencijal&nbsp; 0,50&nbsp; V).&nbsp; Optimizovane&nbsp; analitičke&nbsp; metode&nbsp; su&nbsp; primenjene&nbsp; za&nbsp; određivanje sadržaja H ₂O₂ u komercijalno dostupnim proizvodima za ličnu negu: rastvoru za dezinfekciju (pH 7,50)&nbsp; i&nbsp; rastvoru&nbsp; za&nbsp; či&scaron;ćenje&nbsp; kontaktnih&nbsp; sočiva&nbsp; (pH&nbsp; 4,50).&nbsp; Amperometrijski&nbsp; dobijeni&nbsp; rezultati&nbsp; su&nbsp; u dobrom&nbsp; slaganju&nbsp; sa&nbsp; rezultatima&nbsp; dobijenim&nbsp; primenom&nbsp; tradicionalne&nbsp; spektrofotometrijske&nbsp; metode bazirane&nbsp; na&nbsp; titanijum-sulfatu&nbsp; kao&nbsp; reagensu&nbsp; sa&nbsp; određenim&nbsp; koncentracijama&nbsp; 2,91%&nbsp; i&nbsp; 2,94%&nbsp; zadezinfekcioni rastvor i 3,04% i 3,17% za rastvor zakontaktna sočiva, redom. RSD je bila manja od 2%.&nbsp; Postignuti&nbsp; rezultati&nbsp; su&nbsp; u&nbsp; dobrom&nbsp; slaganju&nbsp; sa&nbsp; sadržajem&nbsp; H₂O₂deklarisanim&nbsp; od&nbsp; strane proizvođača (3%) u oba ispitivana uzorka. Pt-C/CPE je takođe testirana za praćenje koncentracije H₂O₂ u rastvoru za kontaktna sočiva u toku procesa njegove neutralizacije/razgradnje. Nakon 6 h procesa neutralizacije, 24,68&nbsp; &micro;g mL -1 je bila određena koncentracija H ₂O_{2 ,} &scaron;to je ispod dozvoljeneH₂O₂koncentracije u rastvoru za kontaktna sočiva imajući u vidu granicu koja izaziva iritaciju oka. CPE&nbsp; je&nbsp; povr&scaron;inski&nbsp; modifikovana&nbsp; vi&scaron;ezidnim&nbsp; ugljeničnim&nbsp; nanocevima&nbsp; (MWCNT)&nbsp; i kompozitima MnO 2 -MWCNT ili Pt-MWCNT metodom nano&scaron;enja kapi radi pripreme jednostavnih, osetljivih i pouzdanih voltametrijskih senzora za&nbsp; određivanje H ₂O₂u odabranom uzorku. Rezultati SEM/EDS&nbsp; analize&nbsp; kompozitnih&nbsp; materijala&nbsp; su&nbsp; potvrdili da&nbsp; su&nbsp; medijatori,&nbsp; čestice&nbsp; MnO 2 i&nbsp; Pt, nasumično&nbsp; raspoređeni na povr&scaron;ini MWCNT i zastupljeni sa blizu 5% (m:m) u kompozitu izraženopreko Mn i Pt. CV merenja su vr&scaron;ena sa pripremljenim radnim elektrodama u acetatnom (pH 4,50), fosfatnom&nbsp; (pH&nbsp; 7,50)&nbsp; i&nbsp; boratnom&nbsp; (pH&nbsp; 9,18)&nbsp; puferu&nbsp; kako&nbsp; bi&nbsp; se&nbsp; okarakterisalo&nbsp; osnovno elektrohemijsko&nbsp; pona&scaron;anje&nbsp; H ₂O₂i&nbsp; odabrali&nbsp; pogodni&nbsp; radni&nbsp; potencijali&nbsp; za&nbsp; amperometrijsko određivanje ovog ciljnog analita. Pt- WCNT/CPE je primenljiva za rad kako u fosfatnom puferu pH&nbsp; 7,50&nbsp; tako&nbsp; i&nbsp; u&nbsp; acetatnom&nbsp; puferu&nbsp; pH&nbsp; 4,50&nbsp; V&nbsp; kako&nbsp; pri&nbsp; negativnim&nbsp; tako&nbsp; i&nbsp; pri&nbsp; pozitivnim&nbsp; radnimpotencijalima, pri&nbsp; čemu su vrednosti RSD uglavnom ispod 2,5%. U slučaju MnO 2-MWCNT/CPE, na&nbsp; potencijalu&nbsp; 0,30&nbsp; V&nbsp; i&nbsp; vi&scaron;im&nbsp; vrednostima,&nbsp; oksidacioni&nbsp; signali&nbsp; H₂O₂ su&nbsp; signifikantni&nbsp; u&nbsp; blago alkalnoj sredini (pH 7,50), pri pH 4,50 ova elektroda pokazuje nezadovoljavajuće pona&scaron;anje, dok&nbsp; pri pH 9,18 ima prihvatljive performanse. Granice određivanja (GO) su bile u oblasti &micro;g mL -1 . H ₂O₂ je&nbsp; određen&nbsp; u&nbsp; spajkovanom&nbsp; uzorku&nbsp; mleka&nbsp; metodom&nbsp; standardnog&nbsp; dodatka&nbsp; nakon&nbsp; odgovarajuće pripreme&nbsp; uzorka&nbsp; (pH&nbsp; pode&scaron;avanje&nbsp; i&nbsp; centrifugiranje)&nbsp; i&nbsp; primenom&nbsp; optimizovane&nbsp; amperometrijske procedure (acetatni pufer pH 4,50, radni&nbsp; potencijal-0,75 V) koristeći Pt-MWCNT/CPE kao radnu elektrodu. RSD za tri&nbsp; ponovljena merenja je iznosila 2,5%, dok je prinos metode bio ne&scaron;to veći od 71%.Kompozitni materijali koji se sastoje od MWCNT i&nbsp; čestica na bazi Pd (Pd-MWCNT) ili Pt (Pt-MWCNT) su primenjeni za pripremu zapreminski modifikovanih SPCE (Pd-MWCNT-SPCE i Pt-MWCNT-SPCE)&nbsp; i&nbsp; povr&scaron;inski&nbsp; modifikovane&nbsp; SPCE&nbsp; (Pd-MWCNT/SPCE).&nbsp; Ove&nbsp; elektrode,&nbsp; kao&nbsp; i nemodifikovana&nbsp; SPCE&nbsp; i&nbsp; MWCNT-SPCE,&nbsp; su&nbsp; okarakterisane primenom&nbsp; CV&nbsp; i&nbsp; amperometrije&nbsp; u fosfatnom puferu pH 7,50 radi određivanja H ₂O₂ . Pd-MWCNT-SPCE i Pd-MWCNT/SPCE su se pokazale&nbsp; pogodnim&nbsp; za&nbsp; određivanje&nbsp; H ₂O₂ na&nbsp; radnim&nbsp; potencijalima&nbsp; između&nbsp; -0,50&nbsp; i&nbsp; 0,50&nbsp; V,&nbsp; a&nbsp; PtMWCNT-SPCE na ispitivanim radnim potencijalima od -0,80 do 0,70 V. Ove&nbsp; elektrode su zatim modifikovane&nbsp; enzimom&nbsp; glukoza&nbsp; oksidazom&nbsp; (GOx)&nbsp; metodom&nbsp; nano&scaron;enja&nbsp; kapi&nbsp; rastvora&nbsp; GOx&nbsp; i Nafion &reg; -a&nbsp; na&nbsp; njihovu&nbsp; povr&scaron;inu,&nbsp; pri&nbsp; čemu&nbsp; je&nbsp; optimizovana&nbsp; količina&nbsp; nanetog&nbsp; biofilma.&nbsp; GOx/PdMWCNT-SPCE&nbsp; je&nbsp; pokazala&nbsp; bolje&nbsp; analitičke&nbsp; performanse&nbsp; za&nbsp; određivanje&nbsp; glukoze&nbsp; u&nbsp; poređenju&nbsp; sa GOx/Pd- WCNT/SPCE.&nbsp; Kao&nbsp; optimalan&nbsp; radni&nbsp; potencijal&nbsp; GOx/Pd-MWCNT-SPCE&nbsp; je&nbsp; odabranavrednost&nbsp; potencijala&nbsp; -0,40&nbsp; V&nbsp; u&nbsp; odnosu&nbsp; na&nbsp; ZKE,&nbsp; sa&nbsp; zadovoljavajućom&nbsp; linearno&scaron;ću&nbsp; u&nbsp; ispitivanom opsegu&nbsp; koncentracija&nbsp; glukoze&nbsp; od&nbsp; 0,16&nbsp; do&nbsp; 0,97&nbsp; mmol&nbsp; L -1 (od&nbsp; 29,1&nbsp; do&nbsp; 174&nbsp; &micro;g&nbsp; mL -1),&nbsp; dok&nbsp; je&nbsp; GO iznosila 0,14 mmol L -1 (25 &micro;g mL-1 ). Optimizovana metoda zasnovana na GOx/Pd-MWCNT-SPCE je&nbsp; uspe&scaron;no&nbsp; primenjena&nbsp; za&nbsp; određivanje&nbsp; glukoze&nbsp; u&nbsp; uzorku&nbsp; livadskog&nbsp; meda.&nbsp; Dobijeni&nbsp; rezultati&nbsp; su&nbsp; u dobroj&nbsp; saglasnosti&nbsp; sa&nbsp; onima&nbsp; dobijenim&nbsp; primenom&nbsp; komercijalno&nbsp; dostupnog&nbsp; aparata&nbsp; za&nbsp; merenje glukoze. Pogodan radni potencijal za GOx/Pt-MWCNT-SPCE je bio -0,50 V u odnosu na ZKE, pri čemu je zadovoljavajuća linearnost postignuta u ispitivanom opsegu koncentracija glukoze od 65,8 do 260,6 &micro;g mL -1 , sa GO 35 &micro;g mL -1 . Optimizovana metoda zasnovana na GOx/Pt-MWCNT-SPCE je&nbsp; uspe&scaron;no&nbsp; primenjena&nbsp; za&nbsp; određivanje&nbsp; glukoze&nbsp; u&nbsp; u&nbsp; uzorku&nbsp; belog&nbsp; grožđa&nbsp; i&nbsp; uzorku&nbsp; tableta (Traubenzucker-bonbons),&nbsp; pri&nbsp; čemu&nbsp; su&nbsp; dobijeni&nbsp; rezultati&nbsp; u&nbsp; dobroj&nbsp; saglasnosti&nbsp; sa&nbsp; rezultatima dobijenim primenom Accu-Chek aparata.Na&nbsp; osnovu&nbsp; dobijenih&nbsp; rezultata&nbsp; može&nbsp; se&nbsp; zaključiti&nbsp; da&nbsp; su&nbsp; razvijene&nbsp; analitičke&nbsp; metode&nbsp; pre svega jednostavne, pouzdane i pogodne za dobijanje brzih informacija o sadržaju H ₂O₂ u različitim tipovima&nbsp; uzoraka.&nbsp; Svakako&nbsp; odabir&nbsp; pogodne&nbsp; radne&nbsp; elektrode,&nbsp; kao&nbsp; i&nbsp; optimizacija&nbsp; eksperimentalnih uslova su ključni faktori za uspe&scaron;no određivanje H ₂O₂<br>null<br>The aim of this doctoral dissertation was the development of fast and reliable voltammetric methods&nbsp; based&nbsp; on&nbsp; the&nbsp; application&nbsp; of&nbsp; simple&nbsp; and&nbsp; contemporary&nbsp; electrodes/sensors&nbsp; based&nbsp; on carbonaceous materials (carbon paste made of graphite powder and paraffin oil and screen printed carbon electrodes) for the determination of H &nbsp;₂&nbsp;O₂ in the selected complex model and real samples.For this purpose, applicability of different working electrodes was investigated.The&nbsp; amperometric&nbsp; method&nbsp; based&nbsp; on&nbsp; carbon&nbsp; paste&nbsp; electrode&nbsp; (CPE)&nbsp; bulk- modified&nbsp; &nbsp;&nbsp; with 5% (m:m) MnO 2 , under optimized conditions, with a working potential of 0.40 V vs. the saturated calomel&nbsp; elect&nbsp;rode&nbsp; (SCE)&nbsp; and&nbsp; a&nbsp; phosphate&nbsp; buffer&nbsp; solution&nbsp; (pH&nbsp; 7.50)&nbsp; as&nbsp; supporting&nbsp; electrolyte, enabled the quantitation of H &nbsp;₂&nbsp;O₂in the concentration interval from 1.4 to 65 &micro;g mL &minus;1 with a relative standard deviation (RSD) of less than 10%. This meth&nbsp;od was applied for the determination of the H&nbsp;₂&nbsp;O₂consumption&nbsp; in&nbsp; samples&nbsp; of&nbsp; groundwater&nbsp; fro&nbsp;m&nbsp; the&nbsp; Central&nbsp; Banat&nbsp; region&nbsp; (Province&nbsp; of Vojvodina, Serbia) treated by the Fenton (Fe ²⁺and H ₂O₂ ) and Fenton-&nbsp; like (Fe ³⁺and H ₂O₂ ) reagents to remove natural organic matter (NOM) at&nbsp; differentinitial concentrations of iron species, and of their molar ratios to the initial concentration of H₂O₂ . It was found that the form of Fe (Fe ²⁺ or Fe ³⁺ )and the molar&nbsp; ratio to H ₂O₂influenced the degree of the H₂O₂ decomposition in the groundwater with high NOM content. Besides, in the case of the Fenton-like process, for all initial doses of Fe ³⁺ and H&nbsp;₂&nbsp;O₂, a sign&nbsp;ificant amount of H&nbsp;₂&nbsp;O₂ remained unused, whi&nbsp;ch also indicates a lower efficiency of such system compared to the Fenton process. Screen&nbsp; printed&nbsp; carbon&nbsp; electrode&nbsp; (SPCE)&nbsp; bulk-modified&nbsp; with&nbsp; MnO&nbsp;₂ as&nbsp; a&nbsp; mediator&nbsp; was applied&nbsp; for&nbsp; amperometric&nbsp; determination&nbsp; of&nbsp; the&nbsp; H &nbsp;₂&nbsp;O₂ content&nbsp; during&nbsp; the&nbsp; Fenton&nbsp; (Fe ²⁺ ,&nbsp; H &nbsp;₂&nbsp;O₂)&nbsp; and &nbsp;visible&nbsp; light-assisted&nbsp;,&nbsp; photo-Fenton&nbsp; (Fe ^2+&nbsp; ,&nbsp; H &nbsp;₂&nbsp;O₂ ,&nbsp; h&nu;)&nbsp;&nbsp; based&nbsp; removal&nbsp; of&nbsp; neonicotinoid&nbsp; insecticide acetamiprid (ACT). Under&nbsp; optimized conditions (working potential of 0.40 V vs. SCE, phosphate buffer&nbsp; pH&nbsp; 7.50&nbsp; as&nbsp; supporting&nbsp; electrolyte)&nbsp; amperometric&nbsp; determination&nbsp; of&nbsp; H &nbsp;₂&nbsp;O₂showed&nbsp; a&nbsp; linear dynamic range from 0.01 to 1.24 mmol L -1 (from 0.34 to 42.2 &micro;g mL -1) and the RSD did not exceed 4.2%. In the investigated samples (after appropriate pH adjustment from 2.8 to 7.5 instantly after the sampling&nbsp; to stop or maximum decelerate the oxidation processes, filtering, and storage of the deep- frozen sample with defrosting immediately before the measurements) the H &nbsp;₂&nbsp;O₂&nbsp; contents were determined by the standard addition method by analyzing the corresponding amperometric curves. Parallel HPLC-DAD measurements were performed to monito&nbsp;r the concentration/removal of ACT. In the case of the photo- Fenton process (initial concentrations: 0.31; 2.0 and 3.0 mmol L -1 (70.0; 111.7 and 102.1 &micro;g mL -1 ) of ACT, Fe²⁺ and H &nbsp;₂&nbsp;O₂, respec&nbsp;tively) after 10 min of irradiation H &nbsp;₂&nbsp;O₂ was&nbsp; consumed&nbsp; and&nbsp; it&nbsp; can&nbsp; be&nbsp; consi&nbsp;dered&nbsp; that&nbsp; ACT&nbsp; was&nbsp; removed&nbsp; after&nbsp; 5&nbsp; min.&nbsp; During&nbsp; the&nbsp; Fenton process ACT was removed after 20 min of treatment and around 10% of the initial concentration of the H 2O2 remained still unused.CPE&nbsp; was&nbsp; surface&nbsp; modified&nbsp; with&nbsp; a&nbsp; composite&nbsp; of&nbsp; Pt&nbsp; nanoparticles&nbsp; (&lt;&nbsp; 5&nbsp; nm)&nbsp; on&nbsp; graphitized carbon (Pt-C, 10% Pt on Vulcan XC72) by simply dropcoating method. The unmodified CPE and the&nbsp; modified&nbsp; one&nbsp; (Pt-C/CPE)&nbsp; were&nbsp; characterized&nbsp; by&nbsp;&nbsp; EM/EDS&nbsp; and&nbsp; CV&nbsp; measurements.&nbsp; The&nbsp; PtC/CPE showed remarkable electrocatalytic propertiestoward the electrochemical redox reaction of H&nbsp;₂&nbsp;O₂ compared to&nbsp; modified CPE in phosphate buffer (0.1 mol L -1 ; pH 7.50), as well in acetatebuffer&nbsp; (0.1 mol&nbsp; L -1 ; pH .50) supporting&nbsp; electrolytes. Amperometry of&nbsp; H2O2 in the concentration range from 0.15 to 1.45 &micro;g mL -1 with the Pt-C/CPE showed acceptable linearity, while the obtained values of LOQs were 0.06 &micro;g mL -1&nbsp; (pH 7.50, working potential 0.20 V) and 0.10 &micro;g mL -1 (pH 4&nbsp;.50, working potential 0.50 V). The proposed analytical&nbsp; methods were applied to the determination of the H 2O2 content in commercially available personal care products; i.e., disinfection (pH 7.50) and contact lens cleaning solutions (pH 4.50). The obtained amperometric results are in good agreement with those measured by traditional titanium sulfatereagent based spectrophotometric method with determined concentrations as 2.91% and 2.94%&nbsp; for the disinfection product, and 3.04% and 3.17% for the contact lens solution, respectively. RSD was lower than 2%. The obtained results are in a good agreement with the amounts of the H&nbsp;₂&nbsp;O₂declared by producers (3%) in the both investigated samples. The Pt-C/CPE was also tested for monitoring of the H&nbsp;₂&nbsp;O₂ residual concentration in contact lens&nbsp; solution&nbsp; during&nbsp; its&nbsp; neutralization/decomposition&nbsp; rocess.&nbsp; At&nbsp; 6&nbsp; h&nbsp; of&nbsp;&nbsp; neutralization&nbsp; treatment 24.68 &micro;g mL -1 of the H &nbsp;₂&nbsp;O₂was&nbsp; determined which is almost half of the allowedH2&nbsp;O2 concentration in the case of the contact lens solution concerningthe limit of eye irritation. CPE&nbsp; was&nbsp; surface&nbsp;&nbsp; modified&nbsp; with&nbsp; multiwalled&nbsp; carbon&nbsp; nanotubes&nbsp; (MWCNT)&nbsp; and&nbsp; with composites of MnO₂-MWCNT or Pt-MWCNT by drop coating method to prepare simply, sensitive and reliable volta&nbsp;mmetric sensors for the determination of H &nbsp;₂&nbsp;O₂in selected sample. The results of the&nbsp; SEM/&nbsp;EDS&nbsp; analysis&nbsp; of&nbsp; composite&nbsp; materials&nbsp; have&nbsp; confirmed&nbsp; that&nbsp; the&nbsp; mediators,&nbsp; MnO ₂ and&nbsp; Pt&nbsp; articles, are randomly distributed on the surface of MWCNT and represent nearly 5% (m:m) of the composite expressed as Mn and Pt. CV measurements were performed&nbsp; with prepared electrodes in acetate&nbsp; (pH&nbsp; 4.50),&nbsp; phosphate&nbsp; (pH&nbsp; 7.50)&nbsp; and&nbsp; borate&nbsp; (pH&nbsp; 9.18)&nbsp; buffers&nbsp; to&nbsp; characterize&nbsp; the&nbsp; basic electrochemical&nbsp; behavior&nbsp; of&nbsp; H &nbsp;₂&nbsp;O₂ and&nbsp; to&nbsp; select&nbsp; the&nbsp; working&nbsp; potentials&nbsp; suitable&nbsp; for&nbsp; amperometric determination&nbsp; of&nbsp; this&nbsp; target&nbsp; analyte.&nbsp; The&nbsp; Pt-MWCNT/CPE&nbsp; performs&nbsp; well&nbsp; in&nbsp; phosphate&nbsp; buffer pH .50 and acetate buffer solution pH 4.50 in the&nbsp; negative as well as in the positive polarization range with RSD mainly lower than 2.5%. In case of MnO₂-MWCNT/CPE at &nbsp;0.30 V and above the H&nbsp;₂&nbsp;O₂oxidation signal is rem&nbsp;arkable in slightly alkaline media (pH 7.50), at pH 4.50 this electrode showed poor behavior and at pH 9.18 offered acceptable performance. LOQs were in the &micro;g mL -1 concentration&nbsp; range.&nbsp; H&nbsp;₂&nbsp;O₂was&nbsp; determined&nbsp; in&nbsp; a&nbsp; spiked&nbsp; milk&nbsp; sample&nbsp; by&nbsp; standard addition&nbsp; method after&nbsp; appropriate&nbsp; sample&nbsp; preparation&nbsp; (pH&nbsp; adjustment and&nbsp; centrifugation)&nbsp; and&nbsp; using&nbsp; optimized amperometric p&nbsp;rocedure (acetate buffer pH 4.50, working potential -0.75 V) by Pt-MWCNT/CPE as a working electrode. RSD for three repeated measurements was 2.5%, while the recovery of the method was a bit higher than 71%. The&nbsp; composite&nbsp; materials&nbsp; consisting&nbsp; of&nbsp; MWCNT&nbsp; and&nbsp; Pd&nbsp; (Pd-MWCNT)&nbsp; or&nbsp; Pt&nbsp; containing particles&nbsp; (Pt-WCNT)&nbsp; were&nbsp; applied&nbsp; to&nbsp; the&nbsp; preparation&nbsp; of&nbsp; bulk- modified&nbsp; SPCEs&nbsp; (Pd-MWCNTSPCE and Pt-MWCNT-SPCE) and surface modifiedSPCE (Pd- MWCNT/SPCE). These electrodes, as well as unmodified SPCE and MWCNT-SPCE,&nbsp; were characterized by CV and&nbsp; amperometry&nbsp; in phosphate&nbsp; buffer&nbsp; solution&nbsp; of&nbsp; pH&nbsp; 7.50&nbsp; for&nbsp; the&nbsp; H&nbsp;₂&nbsp;O₂determination.&nbsp; Pd-MWCNT-SPCE&nbsp; and&nbsp; PdMWCNT/SPCEare convenient for the etermination of H 2O2 at working potentials from -0.50 to 0.50 V, and Pt-MWCNT-SPCE at investigated working potentials in the range from -0.80 to 0.70 V. These electrodes were then modified with glucose&nbsp; oxidase (GOx) by drop coating a solution of GOxand Nafion &reg; on their surface, whereby the applied amount of biococktail was optimized. GOx/PdMWCNT-SPCE&nbsp; showed&nbsp; better&nbsp; analytical&nbsp; performance&nbsp; for&nbsp; glucose&nbsp; determination&nbsp; in&nbsp; comparison with&nbsp; GOx/Pd-MWCNT/SPCE.&nbsp; The&nbsp; optimal&nbsp; working&nbsp; potential&nbsp; for&nbsp; GOx/Pd-MWCNT- SPCE&nbsp; was -0.40 V vs. SCE and &nbsp;satisfactory linearity was obtained in the investigated glucose concentration range from 0.16 to 0.97 mmol L -1 (from 29.1 to 174&nbsp; &micro;g mL -1 ), hile the LOQ was 0.14 mmol L -1 (25 &micro;g mL -1 ). The optimized method based on GOx/Pd-MWCNT-SPCE was successfully applied to the determination of glucose in multifloral honey sample.&nbsp; The results are in a good agreement with those&nbsp; obtained by commercially available equipment for determination of glucose. Optimal working potential&nbsp; for&nbsp; GOx/Pt-MWCNT-SPCE&nbsp; was&nbsp; -0.50&nbsp; V&nbsp; vs.&nbsp; SCE,&nbsp; and&nbsp; the&nbsp;&nbsp; satisfactory&nbsp; linearity&nbsp; was obtained in the investigated concentration range ofglucose from 65.8 to 260.6&nbsp; &micro;g mL -1 , with LOQ of 35&nbsp; &micro;g mL -1 . The optimized method based on GOx/Pt- MWCNT-SPCE was successfully applied for determination of glucose in white grape and glucose tablets (Traubenzucker-bonbons) samples, whereby&nbsp; the&nbsp; obtained&nbsp; results&nbsp; were&nbsp; in&nbsp; a&nbsp; good&nbsp; agreement&nbsp; with&nbsp; the&nbsp; results&nbsp; obtained&nbsp; by&nbsp; Accu-Chek device. Based on the results, the developed analytical methods are first of all simple, reliable and suitable&nbsp; for&nbsp; obtaining&nbsp; fast&nbsp; information&nbsp; about&nbsp; the&nbsp; content&nbsp; of&nbsp; H ₂O₂ in&nbsp; different&nbsp; types&nbsp; of&nbsp; samples. Certainly the selection of a suitable working electrode, as well as the optimization of experimental conditions are key factors for the successful determination of H₂O₂.

博士<br>元智大學<br>化學工程與材料科學學系<br>99<br>A chemical vapor deposition was employed for decorating the carbon nanotubes (CNTs) onto polyacrylonitrile-based active carbon fabrics (ACF), using acetylene and Ni nanoparticle as carbon precursor and catalyst, respectively. The contact angle of water significantly increases which confirms that the wettability of carbon fabric has shifted to superhydrophobicity due to the structural transformation. Besides, a stable superhydrophobic surface with low contact angle hysteresis using microscale carbon fabrics decorated with submicroscale SiO2 spheres and CNTs is created. A modified Cassie-Baxter model analyzes that the combined effect of SiO2 spheres and CNTs contributes a high area fraction of a water droplet in contact with air, leading to superhydrophobicity. On the other hand, the electrochemical behavior of the carbon electrodes in H2SO4 indicated that the presence of nanotubes not only decreases the distributed capacitance effect and IR drop but also induces double-layer formation and high-rate capability. Gaseous oxidation of carbon papers (CPs) decorated with CNTs with varying degrees of oxidation was conducted to investigate the influence of surface oxides on the performance of electrochemical capacitors. Both superhydrophilicity and specific capacitance of the oxidized CNT/CP composites were found to increase upon oxidation treatment. Amino-functionalization of CNTs attached to CP has been achieved using one synthesis protocol: (i) chemical oxidation, (ii) acyl chlorination, and (iii) amidation. The N-modified CNT/CP capacitor exhibits an enhanced capacitance, high-rate capability, and capacitance stability with high coulombic efficiency. A facile microwave-assisted polyol (MP) approach to synthesize catalysts on carbon composite was presented. The Pt deposits, with an average size of 3–5 nm were uniformly coated over the surface of oxidized CNTs. The Pt catalysts showed not only fairly good electrochemical activity but also durability after a potential cycling of > 1000 cycles. CNTs significantly reduced both connect and charge transfer resistances. With the aid of CNTs, well-dispersed Pt catalysts enable the reversibly rapid redox kinetic since electron transport efficiently passes through a one-dimensional pathway. Bimetallic catalysts with high and stable electrochemical activity toward sulfuric acid (Pt-Co, Pt-Sn) and methanol oxidation (Pt-Zn) were proposed. Experimental results confirmed that two-stage MP synthesis enables the improvement of electrochemical activity, antipoisoning ability and long-term durability of the binary catalyst.

碩士<br>國防大學理工學院<br>化學工程碩士班<br>103<br>The study is divided into three parts, the first part of expanded graphite flake powder filled in the epoxy resin to the kneading manner by changing the mixing time, degassing time, adding a solvent to enhance the heat transfer coefficient. The second part of the epoxy resin as the base material, with different types of graphene different process parameters and flaking of expanded graphite flake as the filler material, through the traditional way of mixing to 15 wt.% of 1100xGnP. It`s k value can be increased to 1.68 W / m • K. Graphene has a high specific surface area, and graphene at 1 wt.% Loading level has improved significantly the effect of thermal conductivity, but with time increase the amount of filler, graphene contact resistance also increases, therefore, enhance the effect of reducing the graphene heat transfer coefficient. In addition, we found 300oC thermal reduction of 300xGnP, TIM development of all its good thermal conductivity and electrical insulation innate its low production cost and conducive to mass production. The third part, due to the thermal interface material in use often promised to insulation, and the resistivity of the carbon material itself is very low, so the simple use of a carbon material as filler material is unlikely, therefore its use boron nitride filler material high thermal conductivity characteristics and a high resistivity characteristic of this nano-carbon material composite of two materials, the thermal conductivity has to maintain and improve the resistivity characteristics. It was found in the use of low thermal expansion of the filling amount of flake graphite and boron nitride composite material, with the best thermal conductivity and high electrical resistivity, B50x11001 its k value of 1.81 W / m • K to resistance value ρ=1014 ohm-cm . In addition, we found that adding 5 wt.% of expanded graphite foil peeling while maintaining a high thermal conductivity and high resistivity condition, has reduced the maximum amount of boron nitride effective to reduce the cost of the thermally conductive composite material. Keyword: Graphene, Exfoliated expandable graphite, Thermal interface materials

碩士<br>元智大學<br>化學工程與材料科學學系<br>104<br>Supercapacitors (SC) have attracted much attention due to their high power densities, wide temperature range, high energy densities and long cycle life compared to batteries. Carbon materials and conducting polymers are common electrode materials for electrical double layer capacitors (EDLC) and pseudo-capacitors, respectively. In order to enhance the performance of the SC, combined carbon materials and conducting polymers to form the hybrid capacitors have been reported. Polyaniline (PANI) is one of the conducting polymers, which has multiple redox states showing large pseudo-capacitance. Carbon nanodot (CND), one of the derivatives of nano carbons, has ultra-small size and unique electronic and optical properties. The CNDs have been recognized as superior electrode material for supercapacitors resulting from quantum confinement effect of wider band gap. Polyaniline/carbon nanodots composites were prepared by chemical oxidation polymerization of aniline in presence of CNDs. After secondary doping, the CNDP-sd composite shows better electrochemical properties and thermal stabilities than pristine PANIs and CNDs. The capacitance of CNDP-sd composite is about 350 F g-1 compared to 187 F g-1 of PANI-sd and 11 F g-1 of CNDs, respectively at a current density of 0.1 A g-1.

博士<br>臺灣大學<br>高分子科學與工程學研究所<br>98<br>In this study, we prepared different conducting polymer and carbon nanotube composites including polyaniline nano-particle, polythiophene derivative and MWNT/PANI core-shell material to discuss their conductivity, EMI shielding efficiency and optoelectrical properties. First section, novel polyaniline (PANI)/epoxy hybrids have been fabricated using an absorption-transferring process in which no organic solvent is involved. An epoxy prepolymer cured by aniline monomer (DGEBA-aniline) was added to a freshly prepared PANI nanoparticles (NPs) aqueous solution with vigorous agitation and heating (ca. 90 C). The PANI NPs were absorbed on the surface of epoxy droplet and then transferred into the whole droplet. The microstructures of the product PANI/epoxy hybrids, characterized using scanning electron microscopy, featured well-dispersed PANI NPs (ca. 40□60 nm) within epoxy matrixes; no large aggregates were observed. The hybrids exhibited huge negative permittivities; the electromagnetic interference shielding efficiency in an electric field at low frequency (100-1000 MHz) was ca. 30-60 dB. The well dispersed PANI NPs not only provided a continuous conducting network but also a higher level of charge delocalization. On other hand, we also synthesized MWNT/PANI core-shell (MPCS) structure, it could also dispersed in DGEBA-Ani through absorption-transferring process. In the section of conducting patterned film, A UV-curable photoresist containing hydroxyl groups has been prepared from a mixture of a photoinitiator, epoxy-acrylate resin, hydroxyethylmethacrylate, and tripropylene glycol diacrylate. Patterns having line widths/spaces of 100/100 μm and 10/5 μm were fabricated on a PET (Polyethylene terephthalate) substrate using lithography techniques. 3-Methyl-3,4-dihydro-2H-thieno[3,4-b]dioxepin-3-yl)methanol (ProDOT-OH) was self-synthesis through urethane-linkages onto the surface of the patterned photoresist on the PET film, which was then dipped into a solution of the other monomer, 3-thienyl ethoxybutanesulfonate (TEBS), and initiator and in situ–polymerized to form conductive poly(ProDOT-OH-co-TEBS) films covering the surface of the patterned resist. The optimal conductivity of the poly(ProDOT-OH-co-TEBS) film was ca. 90 S/cm with an optical transparency of ca. 70%. The conductivity of the film was controlled by the polymerization reaction time and the resolution of the pattern. These conductive patterned films might be applicable to the manufacture of industrial touch panels or chemical/biological sensors. Finally, we prepared nanocomposites of multi-wall carbon nanotubes (MWNTs) and low-energy-bandgap conjugated polymers incorporating 3,4-alkoxythiophene monomers. Poly(3,4-dihexyloxythiophene) (PDHOT) and poly(3,4-dimethoxythiophene-co-3,4-dihexyloxythiophene) [P(DMOT-co-DHOT)] have relatively low energy bandgaps (ca. 1.38 and 1.34 eV, respectively), determined from the onsets of absorbances in their UV–Vis spectra, because of the electron donating effects of their alkoxy groups. MWCNTs have poor solubility in common organic solvents; after surface modification with alkyl side chains using the Tour reaction, however, the MWCNT-HA derivatives were readilydispersed in CHCl3 and could be mixed with the low bandgap polymers. Scanning electron microscopy images revealed that MWCNT-HA was dispersed well in each polythiophene derivative; only a few MWCNT-HA bundles could be observed at a high MWCNT-HA content (＞ 20 wt%). The electrical conductivities of the MWCNT/PDHOT composites were dependent on their MWNT contents, reaching 16 S/cm at 30 wt% MWCNT-HA. We suspect that the two hexyloxy chains of PDHOT enhanced its solubility and allowed it to wrap around the surfaces of the MWCNTs more readily.

碩士<br>國立清華大學<br>化學工程學系<br>97<br>The objectives of this research are the preparation and characterization of poymer composite for the use in thermal interfacial materials (TIM). There are three parts in this study. The first part of this research is to develope the surface coating technologies for using these MWCNTs to template the assembly of silica and alumina nanoparticle. At first, the functionalized multi-walled carbon nanotubes (MWCNTs) were prepared via Friedle-Crafts acylation with Benzenetricarboxylic acid and Gallic acid. Raman spectra and X-ray photoelectron spectroscope (XPS) were utilized to characterize the functionalization of MWCNT.Thermogravimetric analysis (TGA) was used to calculate the organic contents of Benzenetricarboxylic acid and Gallic acid grafted MWCNT (BTC-MWNT and GA-MWCNT), which were 20.1wt% and 7.03wt%, respectively. Second, silane functionalized BTC-MWCNT and GA-MWCNT were prepared via amidation with (3-isocyanatopropyl) triethoxysilane. Raman spectra and X-ray photoelectron spectroscope (XPS) were utilized to characterize the functionalization of MWCNT. The ICPES-BTC-MWCNT and ICPES-GA-MWCNT were utilized as the nano-catchers for inorganic nanoparticles by the covalent incorporation between the silane functionalized MWCNTs and inorganic nanoparticles. The nano silica layer and nano alumina layer coated on the surface of MWCNTs can prohibit the conductive path of electrons. This part intends to investigate (1)the effect of functionalization on the structure of the MWCNTs by Friedel-Crafts modification；(2)the difference in the reactivity of functional groups on the surfaces of MWCNTs affect the morphology of inorganic nanoparticles coated on the MWCNTs；(3)the electrical properties and dispersion of inorganic nanolayer coated the MWCNTs. The ID/IG area ratio of prinstine-MWCNTs, acid treated MWCNTs, BTC-MWCNTs and GA-MWCNTs are 1.08, 1.29, 1.12 and 1.09, respectively. The ID/IG values of BTC-MWCNTs and GA-MWCNTs indicate this modification will functionalize the MWCNTs with slightly or no damage on the structure of MWCNTs. The morphology of inorganic nonoparticles coated on the surface of MWCNTs can be observed by TEM. The coating thickness of SiO2@BTC-MWCNT and Al2O3@BTC-MWCNT are about 7~20nm. The morphology exhibits partially continuous coating, and the silica layer is more smooth than alumina layer. The coating thickness of SiO2@GA-MWCNT and Al2O3@GA-MWCNT are about 5~15nm and the morphology exhibits more continuous coating than those of BTC-MWCNT series. The volume resistivities of SiO2@BTC-MWCNT and Al2O3@BTC-MWCNT increased 106Ω*cm comparising with prinstine-MWCNT (4.71Ω*cm). The volume resistivities of SiO2@GA-MWCNT and Al2O3@GA-MWCNT increased 108Ω*cm comparising with prinstine-MWCNT. Results confirm that the nano silica layer and nano alumina layer coated on the surface of MWCNTs can prohibit the electrical conductive path　effectively. The second part of this research discusses the preparation and characteration of functionalized MWCNTs/epoxy composites. This study investigates the electrical property, dielectrical property, thermal property and thermal conductivity of nanocomposites with various contents of MWCNTs in epoxy matrix. The nanocomposite was prepared with 5phr Al2O3@MWCNTs. The volume resistivity and dielectrical constant of the Al2O3@MWCNTs/epoxy composite were 1.29*1014~5.78*1015Ω*cm and 3.72~4.56, respectively. The glass state CTE α1(coefficient of thermal expansion) and rubber state CTE of the Al2O3@MWCNTs/epoxy composite was decreased from 66.44 ppm/oC to 52.5~45.1ppm/oC (decreased 21~32%) and was decreased from 253.1 ppm/oC to 215~201.1 ppm/oC (decreased 15~20.5%), respectively. The thermal conductivity of the Al2O3@MWCNTs/epoxy composite was increased from 0.13 W/mK to 1.01~1.1W/mK (increased 677~746%). The third part of this research illustrates the preparation and characterization of functionalized MWCNTs/ alumina/ epoxy composites. This study investigates the electrical property, dielectrical property, thermal property and thermal conductivity of the hybrid composites with nano and micro fillers. The hybrid composite was prepared with 5phr Al2O3@MWCNTs、20Vol% alumina and 80Vol% epoxy matrix. The volume resistivity and dielectrical constant of the Al2O3/Al2O3@MWCNTs/epoxy composite were 8.4723*1013~2.1991*1015Ω*cm and 4.41~4.69, respectively. The glass state CTE (coefficient of thermal expansion) and rubber state CTE of the Al2O3@MWCNTs/epoxy composite decreased from 50.16 ppm/oC to 40.27~40.58ppm/oC (decreased 21~32%) and decreased from 201.4 ppm/oC to 143~162.7 ppm/oC (decreased 19~29%), respectively. The thermal conductivity of the Al2O3@MWCNTs/epoxy composite increased from 0.13 W/mK to 1.52~1.95W/mK (increased 1069~1400%). The enhancement of thermal conductivity of hybrid composite was more significant comparising with 60Vol% alumina/ epoxy composite (1.58 W/mK). The overall performance of hybrid composite with nano and micro fillers exhibited sinficant improvement.

碩士<br>逢甲大學<br>航太與系統工程學系<br>106<br>Carbon nanotubes (CNT) possess excellent mechanical, electric, and thermal behavior and are considered as a potential material. However, due to their sizes, CNTs tends to be entangled. This problem hinders wider applications of CNT materials. One possible solution is the use of CNT films, also known as Buckypaper. The CNT film is made based on the entangling of CNTs in a 2D plane. This film is self-standing, easy to handle, and flexible. In this research, we used a porous thermoplastic (TP) film for filtrating nanofibers, including CNTs and VGCFs, with a fixed ratio. The TP film with the deposited nano-fibers is then subjected to hot pressing and consolidation, leading to a nano-fiber/TP composite. This film like composite is flexible. There are two parameters to study: the first is the CNT/VGCF ratio, the second is different TP films. By varying these two, TP composites were made and the tensile properties are tested. After the tests, the fractured sections of the specimens were examined by FE-SEM. According to the tensile testing, the PA-based matrix composite provides the best interface bonding. The tensile strength and modulus are higher. The sulfated PP composite provides better properties. Using longer VGCFs also results in better load transferring and a higher tensile strength. The SEM pictures reveal distribution of the nano-fibers and voids within the matrix.

碩士<br>中原大學<br>化學研究所<br>95<br>Abstract In this Master dissertation, we have preparation and properties of nano-gold attached mercaptoaniline complex membrane and carbon nanotubes/nano gold particles composites, respectively. They were studied on the optical clarity and other properties discussion. For chapter 3, Poly (ANI-co-MANI)/Au composite film was prepared by a facial process with well-dispersed on its surface. The hydrosulfide group (-SH) contained by the Poly (ANI-co-MANI) was play an important role as a bridge base on the -S-Au bonding. This bond is well-known to react and form easily so that a original procedure has been developed. This advantageous consequence would be helpful for practical manipulation, in particle for the biosensor and bio-catalysis devices. For chapter 4, we present the novel assemblies by anchoring gold nanoparticles of ~ 10 nm diameter to sidewalls and ends of carbon nanotubes (CNTs) via covalent interaction between gold nanoparticles and thiol-terminated CNT surfaces. Mercaptoaniline was first grafted onto the surface of nanotubes by covalent interaction between primary amine groups of mercaptoaniline and carbon nanotube surface to give thiol-terminated CNTs. Subsequently, gold nanoparticles were anchored to the surface of nanotubes through covalent interaction between thiol-terminated nanotubes and gold nanoparticles. This new assemblies of carbon nanotubes (CNT) and gold nanoparticles were obtained with mercaptoaniline as molecular bridge. These assemblies were confirmed further by transmission electron microscopy, FTIR-ATR, UV-visible, Raman spectroscopy and X-ray powder diffraction.

博士<br>國立清華大學<br>動力機械工程學系<br>101<br>Abstract The surface modification of carbon nanotubes (CNTs) has been recently observed to influence the distribution of CNTs in epoxy resin and the mechanical properties and electrical conductivities of these CNTs. Accordingly, the treatment of CNTs to with organic acids to oxidize them generates functional groups on the surface of CNTs. This investigation studies the consequent enhancement of the mechanical properties and electrical conductivities of CNTs. The influence of adding various proportions of CNTs to the epoxy resin on the mechanical properties and electrical conductivities of the composites thus formed is investigated, and the strength of the material is tested at different temperatures. The test results also indicate that mechanical strength and electrical conductivity increase with the amount of CNTs added to the composites. Different coefficients of expansion of the matrix, fiber and CNTs, are such that overexpansion of the matrix at high temperature results in cracking in it. An SEM image of the fracture surface reveals debonding and the pulling out of longitudinal fibers because of poor interfacial bonding between fiber and matrix, which reduce overall strength. Moreover, the creep behaviors of carbon fiber (CF) /epoxy resin thermosetting composites and CNTs/CF/ epoxy resin composites were tested and analyzed at different stresses, orientations of fiber, temperatures and humidities. The creep exhibits only two stages- primary creep and steady-state creep. The effects of creep stress, creep time, and humidity on the creep of composites that contain various proportion of CNTs were investigated at various temperatures. Additionally, increasing the number of cycles in cyclic creep tests at room temperature resulted in a decrease in creep strain even at a high temperature of 55℃. Possible room temperature creep mechanisms have been proposed and discussed. With increasing number of creep tests, the creep strain decreased due to strain hardening which occurred during creep. Creep strain is believed to increase with applied stress, creep time, humidity, temperature and degree of the angle θ between the orientation of fiber and the direction of the applied stress. Furthermore, the decrease of creep strain of CF/epoxy resin composites performed aging pretreatment in a constant temperature and humidity chamber for different long-term days prior to creep testing was also investigated. Finally, the test results of creep strain of CF/epoxy resin composites and CNTs/CF/epoxy resin composites tested under various conditions can be smoothly fitted by the fitting curves of Findley power law. And Larson-Miller equation can be adopted to precisely predict the low-temperature-long-term creep behavior by the high-temperature-short- term creep behavior.

Conductive polymers are promising pseudo capacitive materials as they feature both good conductivity and high capacitance. Formation of composite between conductive polymers and carbon nanotubes is a proven technique in enhancing the material electroactivity. In-situ polymerization of conductive polymers includes polyaniline, polypyrrole and PEDOT: PSS and composite with MWCNT has been successfully achieved. Composites fabricated by using different dopants and their performance were studied. Excellent achieved capacitive performance is due to the combination of pseudo capacitance and double layer capacitance. The MWCNTs content has significant influence on the morphology and structure of the polymerized ECP in the composite. And therefore affects the material conductivity and the charge storage performance. Two electrodes cell performance shows that Ppy/MWCNT composite shows a more promising performance as electrode materials for EC applications in contrast to PANI/MWCNT and PEDOT: PSS/MWCNT composites.

碩士<br>大葉大學<br>工業工程與管理學系<br>105<br>Carbon fiber composite material with light weight, high strength, high temperature, corrosion resistance and conductivity and other excellent features. So most of the aircraft used in the industry, steam locomotive industry, bicycle industry and medical and health industries. However, if the carbon fiber composite products to be lightweight and maintain the high-strength nature of the need for new materials research and development and manufacturing. In this study, the carbon nanotubes in the nanometer powder and the graphene were used as reinforcing reinforcement in the carbon fiber composite material. First,0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt% %, 2.5 wt% of the nano-powder by weight of the carbon fiber composite material to test, to observe the bending strength and ultimate strength to find the best weight percentage. The experimental results show that when the addition of carbon nanotubes to 1.5wt% and graphene addition to 1.0%, the mechanical properties of the best. (1: 5, 1: 3, 1: 1, 3: 1, 5: 1) were used to detect the mechanical properties by the preliminary study data. The experimental results show that when the ratio of carbon nanotubes to graphene is 1: 1, the ultimate strength and tensile strength can be improved.

碩士<br>大同大學<br>材料工程學系(所)<br>104<br>Many of the capacitor dielectric material is difficult to be designed thinner. In the microelectronics industry, the dispersion component accounted for 90% of the area of the circuit board, wherein the capacitor is a main object, and as such hinders the miniaturization of the capacitor development. Footprint embedded capacitor is small, you can make the packing density of the circuit board has improved significantly, the development and application of embedded capacitor is very important. CaCu3Ti4O12 (CCTO) dielectric ceramics are of concern in recent years, high dielectric material has a high dielectric constant at a frequency of 10Hz and a stable temperature in the range of 100-400K, CaCu3Ti4O12 (CCTO) / polymer composite dielectric material the more research attention. This study will be prepared by solid state reaction CaCu3Ti4O12 powder, a planetary ball mill CaCu3Ti4O12 powder fining with different proportions of carbon black mixed in different proportions filled PMMA prepare a dielectric composite material, the dielectric properties, used in embedded capacitors.

Yes<br>In this paper, two types of nano carbon materials including 0D nano carbon black and 2D graphene are assembled through electrostatic adsorption to develop smart cement-based composites. Owing to their excellent mechanical, electrical properties and synergistic effect, self-assembled 0D/2D nano carbon materials can form toughening and conductive networks in cement-based materials at low content level and without changing the preparation process of conventional cement-based materials, thus endowing cement-based materials with smart and multifunctional properties including high toughness, self-sensing property to stress/strain and damage, shielding/absorbing property to electromagnetic wave. The developed smart cement-based composites with self-assembled 0D/2D nano carbon materials have promising application in the fields of oil well cementing, structural health monitoring, and electromagnetic protection and anti-electromagnetic pollution. It can therefore conclude that electrostatic self-assembled 0D/2D nano carbon materials provide a simple preparation method and excellent composite effect for developing nano cement-based materials, which can be applied in large-scale infrastructures.<br>The National Science Foundation of China (51908103) and the China Postdoctoral Science Foundation (2019M651116).<br>The full-text of this article will be released for public view at the end of the publisher embargo on 22 Nov 2021.

Multi-scale reinforcement of composite materials is a topic a great interest owing to the several advantages provided, e.g. increased stiffness, improved aging resistance, and fracture toughness. It is well known, that the fracture toughness of epoxy resins used as matrix materials for CFRP composites can be increased by the addition of nano-sized fillers such as Carbon nanotubes (CNTs). CNTs are particularly well suited for this purpose because of their nano-scale diameter and high aspect ratio which allow enhancing the contact area and adhesion to the epoxy matrix. On the other hand, CNTs can also be used to improve the interlaminar strength of composite, which is the resistance offered to delamination. Several fabrication techniques have been devised to this purpose, such as powder dispersion [51-53], spraying [54], roll coating [2] and electrospinning [55, 56]. The aim of this work is to extend the knowledge in this field. In particular, MWCNTs were dispersed throughout the interface of a carbon fiber composite laminate ([0o]16) through spraying and the resulting fracture toughness was investigated in detail. To this purpose, Double Cantilever Beam (DCB) specimens were fabricated by placing 0.5 wt.% CNTs at the interface of mid-plane plies and the fracture toughness was determined using the ASTM standard procedures. For comparison, baseline samples were prepared using neat prepregs. In order to corroborate the variation of fracture toughness to the modifications of interfacial damage mechanisms, Scanning Electron Microscopy (SEM) of the failed surfaces was also undertaken. The results of this work have shown that functionalized MWCNTs can enhance the interlaminar fracture toughness; indeed, compared to the neat case, an average increase around 17% was observed. The SEM analysis revealed that the improved fracture toughness was related to the ability of the Nano-reinforcement to spread the damage through crack bridging, i.e. CNTs pull-out and peeling.

博士<br>逢甲大學<br>機械與航空工程博士學位學程<br>102<br>Properties of composite materials related to the action of dispersion within a matrix. This article uses the Exfoliated Graphite (EG) and the Carbon Nanotube (CNT) materials, the fluffiness of the porous materials are mixed with the resin; however, due to the fact that the pores are extremely small, the resin can&;#39;t enter into the pores of the nanomaterials. If the filling nanomaterials can&;#39;t be evenly dispersed within the resin it will cause pores or cracks in the composites, and the physical properties of the composites will decrease. EG has the beneficial property of having a high surface area, which is extremely fluffy with low density. When EG is mixed with epoxy, if the nanomaterials have more than 5% of the weight by percentage, then they will have a poor mixing effect with the resin. Due to the extremely tiny size of the CNT, there is a serious agglomeration since it is not effectively separated. CNT has more bulk and lower density than the EG; again, more than 5% of the weight by percentage that is mixed with the resin is ineffective. Solving the above problem, this paper uses the three-roll-mill (TRM) method to improve the material dispersion. Mixed with the nanomaterials (EG or CNT), we found that the weight percentage is too high and the mixing effect remains poor. Therefore, use of TRM without the weight percentage of the filling material to enhance the conditions improves the dispersion of materials and increases the basic properties. This can save material, improve the situation and ensure the material is homogeneous. The epoxy is the matrix, and is mixed with filling nanomaterial to make composites. The TRM can effectively make nanomaterials to be mixed with epoxy. TRM can further reduce the gap and increase the roll speed of the ways in which the nanomaterial and epoxy generate shear stress, and the epoxy can penetrate deeply into the nano-porous of the nanomaterial. The outer edge of the nanomaterial can be uniformly coated with epoxy, and can’t be re-aggregated. The roller gap arising due to the shear stress can also cause the EG stripping even further into the Graphite Nanosheet (GNS). In addition, to upgrade the dispersion property of carbon nanotubes, it can also use the CNT entangling characteristics to produce Buckypapers. CNT is mixed with ethanol, then using ultrasonic for further mixture. The vacuum device was used to reinforce the filter effect for making the ultrathin Buckypapers. Epoxy has been used to make the Buckypapers composite because the ultrathin Buckypapers is very weak. The mechanical properties of the composite were studied with good results.

碩士<br>大葉大學<br>工業工程與科技管理學系<br>95<br>The main object of this paper is developed a miniature flat-panel speakers stiffened by nano-carbon tube composites which are low frequency sound quality, smooth curve of sound pressure, and reduce the decay rate of high frequency sounds. The several standard of flat-panel speakers stiffened including the 30mm×18mm×7mm、40mm×14mm×7mm and 50mm×14mm×7mm. The paper is used the ANSYS software to solved the sound curve in flat-panel speakers stiffened and used optimal theory to solved optimal manufacture parameters (including the thickness ratio of flat-panel speaker and nano-carbon tubes that in the same weight, boundary condition and spring constant of suspension system, vibration area and location) which make the sound pressure value curve is smooth in global frequency. The flat-panel speakers stiffened which is developed by this project can reach the goals of economize electric power, maximum bearing, the low-frequency had powerful voices and the high-frequency had a better clarity. According to the best results of manufacture parameters, the materials and molds of suspension system are choused to manufacture suspension systems and fabricate miniature flat-panel speakers stiffened. The experimental and optimal methods are presented to study the optimal sound pressure curve of flat-panel speaker. The optimal methods proved to be accuracy.

碩士<br>國立臺灣科技大學<br>機械工程系<br>99<br>In this study we proposed an innovative piezoresistive sensing device fabricated with carbon nano-fiber thin film. The device is able to detect three-dimensional forces and with excellent flexibility. Besides, the fabrication process of this device is simpler than that of traditional force sensors, and easy to be produced by mass production. The device has four strain sensors made on a polyimide substrate by patterning surface treatment and tilted-drop process. The hydrophilic and hydrophobic surface treatments were performed by atmospheric plasma, and the treated surfaces are investigated by contact angle measurement, x-ray photo electron spectroscopy and scanning electron microscope to study their functional groups, element composition and morphological surface profile. The fabricated flexible device which has four sensors in opposite directions can recognize three-dimensional forces by means of measuring and analyzing the resistance of the four sensors. The flexible device was applied to develop a cursor pointing device. A PSoC chip with built-in OP amplifier, analog to digital converter and multiplexer was used to develop a scanning circuit for the cursor pointing device. We successfully demonstrated to move the computer screen cursor by the developed cursor pointing device.

碩士<br>大葉大學<br>工業工程與科技管理學系<br>98<br>The main object of this paper is designed and developed a double flat-panel speaker stiffened by nano-carbon tube composites which it had thin thicknesses, broad frequency and acoustic fidelity vigorous not distorted it. Two types of vibrating plate, namely, a high audio speaker and medium-low audio speaker constructed on the basis of the manufacture technique and sound pressure theory are developed for the design and analysis of double flat-panels. The study is analyzed the frequency and sound pressure value of double flat-panel speakers with different design parameters such as stiffness and weight of composite panels, boundary condition and spring constant of suspension system and vibration area which are constructed using a finite element constructed on the basis of the software ANSYS. The double flat-panel speakers can be applied to the general plane video and music electronic products loudspeaker system, achieves nowadays pursues the monitor more and more thin tendency. The double rectangular flat-panel speaker can be used in dual-channel flat-panel speakers for portable DVD players and notebook computers ... and other products. According to developed the analytical method of a set of simulation and optimal design is proceed to optimal design of multiple objective function for stiffened composite double flat-panels in 100Hz~20KHz frequency zones. The 100Hz~20KHz frequency zones had divide into 4 zones, every zones variable values multiply by weight was the sum that was the objective function of multiple optimal design. In the limit small thrust of low power, is used the optimal method to find the best manufacturing parameters (includes the lengths of flat-panel speaker, spring constant of suspension system, stiffened types and vibration lengths) made the sound pressure value curve had smooth and get the best sound pressure value. Therefore, the optimal manufacturing parameters would manufacture double flat-panels to measured sound pressure curve that compared experimental values and theory values.

博士<br>國立清華大學<br>材料科學工程學系<br>101<br>In this dissertation, the investigations on the thermal properties and electromagnetic interference shielding efficiency (EMI SE) of nanoscale carbon materials/polymer composites have been studied. The fillers such single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphite nanosheets (GNS), graphene (GP), and the graphene decorated with Ag (Ag@GP) and Ni (Ni@GP) were synthesized successfully, and incorporated with various polymers including paraffin and polyaniline (PAni), respectively. Two paraffin composites filled separately with randomly distributed graphite nanosheets (R-GNS) and oriented graphite nanosheets (O-GNS) were fabricated, and their thermal properties and structural characteristics were investigated. The experimental results show that a conductive network at 1.0 wt% GNS loading was found. The thermal conductivities of the R-GNS/paraffin and the O-GNS/paraffin composites are 4.47±0.15 and 1.68±0.07 W/m K, respectively, when 5.0 wt% GNS were introduced. The Maxwell-Euken model and the modified rule of mixtures model were proposed to predict the thermal conductivities of the R-GNS/paraffin and the O-GNS/paraffin composites, respectively. The melting point and the solid-liquid phase transition temperature of the R-GNS/paraffin composites are approximately 53 and 60 0C, respectively, and neither of these values was significantly affected by the presence of GNS. Decreases in the latent heat of the R-GNs/paraffin composites with increased GNS loading were also found. This work demonstrates the fabrications and characterizations of PAni composites containing SWCNTs, GNS, or hybrid fillers SWCNTs/GNS. The characterization of microstructure, examination of fracture surface morphologies, and measurement of electric conductivity and EMI SE were performed. It was found that both the electric conductivity and the EMI SE increase with filler loading, and the nanocomposites filled with 1.0 wt% SWCNTs/GNS possessed the highest electric conductivity of 16.2 S/cm and total EMI SE of 27.0 dB. The experimental results also show that absorption is the primary mechanism of EMI SE for all of the loadings and fillers. To develop novel EMI shielding materials, PAni composites filled with GP, GP decorated with silver nanoparticles (Ag@GP), and GP decorated with nickel nanoparticles (Ni@GP) were prepared, and the microstructures, morphologies, electrical conductivities, and EMI SE of the composites with different filler loadings (0.5, 1.0, 3.0, and 5.0 wt%) were investigated. The PAni composite containing 5.0 wt% Ag@GP showed the best electrical conductivity of 20.32 S/cm and highest EMI SE of 29.33 dB. The uniform dispersion of fillers significantly enhanced the formation of conductive pathways in the PAni matrix, and the presence of metal nanoparticles on the GP surface and between the GP layers also increased the electrical conductivity. The results of this study show that absorption is the primary factor governing EMI shielding, which is attributed to the high permittivity of the composites. This study reveals that the Ag@GP/PAni composite is promising for applications as an EMI shielding material. Porous composites fabricated through a simple dip-coating method demonstrated excellent performance in EMI shielding. A commercial sponge was coated with silver nanoparticles before being dip-coated with GP, MWCNTs, or hybrid GP/MWCNTs to form Ag/carbon nanomaterial hybrid composites. Herein, we found an insignificant difference in EMI SE among the porous composites without the Ag nanoparticle coating, with values of approximately 14.4 dB. Interestingly, the hybrid composites with the Ag nanoparticle coating exhibited excellent EMI shielding (24.33 dB). The EMI SE measurements showed that reflection dominates the EMI SE for all the sponge composites studied in this work due to their porous structure.