The aim of this study was to improve electrical properties of conductive polymer composites. For this purpose, various studies were performed using different materials in this dissertation. In order to investigate the effect of alternative composite preparation methods on electrical conductivity, nylon 6/carbon black systems were prepared by both in-situ polymerization and melt-compounding techniques. When compared with melt compounding, in-situ polymerization method provided enhancement in electrical conductivity of nylon 6 composites. Furthermore, it was aimed to improve electrical conductivity of polymer composites by modifying surface chemistry of carbon black. 1 wt. % solutions of 3-Aminopropyltriethoxysilane and formamide were tried as chemical modifier, and treated carbon black was melt mixed with low-density polyethylene (LDPE) and nylon 6. According to electron spectroscopy for chemical analysis (ESCA), chemicals used for surface treatment may have acted as doping agent and improved electrical conductivity of polymer composites more than untreated carbon black did. Formamide was more effective as dopant compared to the silane coupling agent. In order to investigate electromagnetic interference (EMI) shielding effectiveness and dielectric properties of conductive polymer composites, 1, 2 and 3 wt. % solutions of formamide were tried as chemical modifier and treated carbon black was melt mixed with poly(ethylene terephthalate) (PET). Composites containing formamide treated carbon black exhibited enhancement in electrical conductivity, EMI shielding effectiveness and dielectric constant values compared to composites with untreated carbon black. In order to enhance electrical conductivity of polymer composites, the selective localization of conductive particles in multiphase polymeric materials was aimed. For this purpose, carbon nanotubes (CNT) were melt mixed with polypropylene (PP)/PET. Grinding, a type of solid state processing technique, was applied to PP/PET/CNT systems to reduce the average domain size of blend phases and to improve interfacial adhesion between these phases. Grinding technique exhibited improvement in electrical conductivity and mechanical properties of PP/PET/CNT systems at low PET compositions. To investigate application potential of conductive polymer composites, polyaniline (Pani)/carbon nanotubes (CNT) composites were synthesized and electrochemical capacitance performances of these systems, as electrode material in electrochemical capacitors, were studied. Polyaniline/carbon nanotubes composites resulted in a higher specific capacitance than that of the composite constituents. Pseudocapacitance behavior of Pani might contribute to the double layer capacitance behavior of nanotubes. Additionally, as an alternative to Pani/CNT systems, polyaniline films were deposited on treated current collectors and electrochemical capacitance performances of these electrode systems were investigated. The highest specific capacitance of polyaniline/carbon nanotubes composites was 20 F/g and this value increased to 35.5 F/g with polyaniline film deposited on treated current collector.

Indium tin oxide (ITO) thin films have been used as transparent electrodes in many technological applications such as display panels, solar cells, touch screens and electrochromic devices. Commercial grade ITO thin films are usually deposited by sputtering. Solution-based coating methods, such as sol-gel however, can be simple and economic alternative method for obtaining oxide films and also ITO. In this thesis, &ldquo / ITO sols&rdquo / and &ldquo / ITO nanoparticle-incorporated hybrid ITO coating sols&rdquo / were prepared using indium chloride (InCl3

The thin film deposition system using ultrasonic nebulization was adopted in this study. SnCl4.5H2O, SbCl3, and TaCl5 were used as solutes. Ethanol was used as the solvent. Solutions of different Sn4+ concentration, Sb concentration (Sb/Sn atomic ratio) in Sn, and Ta concentration (Ta/Sn atomic ratio) in Sn were mixed. The mist was generated from a solution by the agitation of an ultrasonic device operating at about 1.65MHz. The mist was carried to the heated substrate (corning 7059 glass) by the flow of nitrogen gas so that it was decomposed by heat. SnO2-x films were deposited on the substrate due to the pyrolysis reaction. The experiment included six series: Sn4+ concentration series, Sb-doping series, temperature series, Ta-doping series, aging time series and nebulization rate series. SnO2-x films were analyzed by XRD, UV-Visible, SEM, and Hall-measurement. The optimum deposition conditions were obtained through analyses of these six series. The film deposition rate of nonaged solution was faster than aged solution. When the nebulization rate of solution was 1.6 ml/min, the resistivity of undoped SnO2 film obtained with the substrate kept at 450 oC is 2.364¡Ñ10-2£[-cm and the maximum transmittance of the visible light is 78.7%. When Sb/Sn atomic ratio in the solution was 2%, the resistivity of Sb doped SnO2 film obtained with the substrate kept at 525 oC is 2.77¡Ñ10-3£[-cm and the maximum transmittance of the visible light is 71% . When Ta/Sn atomic ratio in the solution was 0.1%, the resistivity of Ta doped SnO2 film obtained with the substrate kept at 450 oC is 3.917¡Ñ10-2£[-cm and the maximum transmittance of the visible light is 85% In this study, the electro-optical properties of Sb and Ta doped SnO2 thin films derived from an ultrasonic nebulization process were reported and discussed carefully through film characterizations.

Having conducted the research described in this thesis I found that there exists a possibility to produce polyelectrolyte nanostructures on hydrophobic surfaces by application of the moving contact line approach. It was demonstrated that the morphology of nanostructures displays a range of structure variations from root-like to a single wire structure with a high anisotropy and aspect ratio (providing diameters of several nanometers and the length limited by the sample surface dimensions). Such nanostructures can be produced exactly on the spot of interest or can be transferred from the surface where they were produced to any other surfaces by the contact printing technique. A model describing the polymer deposition during the moving contact line processes on hydrophobic surfaces has been proposed. The application of this model provides the ground for an explanation of all the obtained experimental data. Utilizing moving contact line approach aligned one-dimensional polycation structures were fabricated and these structures were used as templates for assembling amphiphile molecules. Quasiperiodic aligned and oriented nanostructures of polyelectrolyte molecules formed in moving droplets were utilized for fabrication of electrically conductive one-dimensional nanowires.

Polymer electrolyte membrane fuel cells (PEMFCs) have the potential to play a major role as energy generators for transportation and portable applications. One of the current barriers to their commercialization is the cost of the components and manufacturing, specifically the bipolar plates. One approach to preparing PEMFCs for commercialization is to develop new bipolar plate materials, related to mass production of fuel cells. Thermoplastic/carbon filler composites with low filler loading have a major advantage in that they can be produced by a conventional low-cost injection molding technique. In addition, the materials used are inexpensive, easy to shape, and lightweight. An optimal bipolar plate must possess high surface and bulk electronic conductivity, sufficient mechanical integrity, low permeability, and corrosion resistance. However, it is difficult to achieve high electrical conductivity from a low-cost thermoplastic composite with low conductive filler loading. Concerns over electrical conductivity improvement and the injection processability of composites have brought forth the idea of producing a polypropylene/three-carbon-filler composite for bipolar plate application. The thesis addresses the development of synergistic effects of filler combinations, investigating composite conductive materials and using composite bipolar plate testing in PEMFCs. One significant effect of conductive network formation is the synergetic effects of different carbon filler sizes, shapes, and multiple filler ratios on the electrical conductivity of bipolar plate materials. A polypropylene resin combined with low-cost conductive fillers (graphite, conductive carbon black, and carbon fibers with 55 wt% of filler loading) compose the main composite for all investigations in this research. Numerous composite formulations, based on single-, two-, and three-filler systems, have been created to investigate the characteristics and synergistic effects of multiple fillers on composite conductivity. Electrical conductivity measurements corresponding to PEMFC performance and processing characteristics were investigated. Experimental work also involved other ex-situ testing for the physical requirements of commercial bipolar plates. All combinations of fillers were found to have a significant synergistic effect that increased the composite electrical conductivity. Carbon black was found to have the highest influence on the increase of electrical conductivity compared to the other fillers. The use of conjugated conducting polymers such as polypyrrole (PPy) to help the composite blends gain desirable conductivities was also studied. Electrical conductivity was significantly improved conductivity by enriching the conducting paths on the interfaces between fillers and the PP matrix with PPy. The conductive network was found to have a linkage of carbon fibers following the respective size distributions of fibers. The combination of Fortafil and Asbury carbon fiber mixture ameliorated the structure of conductive paths, especially in the through-plane direction. However, using small fibers such as carbon nanofibers did not significantly improve in electrical conductivity. The useful characteristics of an individual filler and filler supportive functions were combined to create a novel formula that significantly improved electrical conductivity. Other properties, such as mechanical and rheological ones, demonstrate the potential to use the composites in bipolar plate applications. This research contributes a direction for further improvement of marketable thermoplastic bipolar plate composite materials.

Electrospun, non-woven, fibers have high surface area compared to conventional cast films. The thesis reports on the modification of electrospun fibers to concentrate and/or detect biohazards. In one study, electrospun fibers with affinity for the lectins ricin/concanavalin A were fabricated using molecular imprinting or through binding to immobilized antibodies, aptamers or lectin specific sugars. Attempts to fabricate imprinted electrospun fibers through inclusion of the template during the spinning process proved unsuccessful. However, electrospun fibers with affinity towards biohazards were successfully produced by post-modification with antibodies, aptamers or lectin specific saccharides. With regards to the latter, dextran, mannose and chitosan were immobilized onto nylon electrospun fibers that were partially hydrolyzed or treated with cyanuric chloride. The sugar-modified fibers bound significantly higher amount of lectins. Electrospun fibers were also fabricated, post modified with antibodies to capture and detect Salmonella. The study has illustrated the utility of electrospun fibers for biohazard diagnostics. / The National Center for Food Protection and Defense. USA

Accurate values of thermophysical transport properties of particle beds are necessary to accurately model heat and mass transfer processes in particle beds that under-go preferred processes and changes. The objective of this study is to use a proven analytical/numerical methodology to estimate the unknown transport properties within test cells filled with silicagel particles and compare the results with the previously published data. An experimental test cell was designed and constructed to carry out transient heat transfer tests for both step change conduction and convection heat transfer within a packed bed of silicagel particles. For a known step change in the test cell temperature boundary condition, the temporal temperature distribution within the bed during heat conduction depends only on the effective heat conduction coefficient and the thermal capacity of the particle bed. The central problem is to, using only the boundary conditions and a few time-varying temperature sensors in the test cell of particles, determine the effective thermal conductivity of the test bed and specify the resulting measurement uncertainty. A similar problem occurs when the heat convection coefficient is sought after a step change in the airflow inlet temperature for the test cell. These types of problems are known as inverse heat transfer problems (IHTP). In this thesis, IHTP method was used to estimate the convective heat transfer coefficient. Good agreement was seen in experimental and numerical temperature profiles, which were modeled by using the estimated convective heat transfer coefficient. The same methodology was used to estimate the effective thermal conductivity of the particle bed. Comparison between the experimental temperature distribution and numerical temperature distribution, which was modeled by using the estimated effective conductivity, illustrated good agreement. On the other side, applying the effective thermal conductivity, obtained from a direct steady state measurement, in the numerical simulation could not present agreement between the numerical and experimental results. It was concluded that the IHTP methodology was a successful approach to find the thermophysical properties of the particle beds, which were hard to measure directly.

The purpose of this research was to investigate the factors that enhance conductive anodic filament (CAF) formation in printed wiring boards. The variables studied were (1) flux formulation, (2) conductor spacing, (3) operating voltage, and (4) temperature. A Weibull distribution of failure times due to CAF was observed. A novel test circuit was designed and implemented that allowed the mean time to failure to be determined for boards processed with three different fluxes, at 0.5 mm and 0.75 mm conductor spacings and at 150V and 200V. The boards were aged at 85%RH and a temperature of 75°C, 85°C or 95°C. It was found that the flux formulation affected the rate of CAF formation. A modified linear aliphatic polyether flux with a chloride activator had a significantly different activation energy than control printed wiring boards or those boards processed with a poly(ethylene/propylene) glycol flux or a poly(ethylene/propylene) glycol flux with a bromide activator. The addition of bromine to a poly(ethylene/propylene) glycol flux decreased the rate of CAF formation as compared to poly(ethylene/propylene) glycol without a halide activator. The inter-relation between voltage and conductor spacing was quantified as a L4/V2 relationship for the plated through hole test pattern used in this study. 325V/mm was found to be a critical voltage gradient for the formation of CAF. The maximum temperature of the reflow profile also greatly enhances CAF formation and decreases the mean time to failure. Microscopic analysis showed distinct differences in CAF morphology between the various processed boards. Control boards had small halo-like CAF formations around a separated fiber / epoxy interface. CAF that formed on boards processed with poly(ethylene/propylene) glycol or poly(ethylene/propylene) glycol with a bromine activator had a stratified appearance that penetrated well into the epoxy. Boards that were processed with the modified linear aliphatic polyether with chlorine activator had a striated morphology that also penetrated into the epoxy. All CAFs were consistently copper and chlorine containing despite the use of a bromine containing flux. Electron diffraction revealed that a CAF observed in this study was synthetic atacamite. Stainless steel (i.e., iron, nickel, and chromium) residues were also observed as a result of drill bit breakage during PTH formation.

Electrically conductive adhesives (ECA) are discussed and studied with everincreasing interest as an environmentally friendly alternative to solder interconnection in microelectronics circuit packaging. They are used to attach surface mount devices (SMD), Integrated Circuits (IC) and Flip chips in electronic assembly. The use of ECAs brings some benefits like flexibility, mild processing conditions and process simplicity. Multi walled carbon nanotubes (MWCNT) are used instead of metal fillers because of their novel properties such as light weight, high aspect ratio, corrosion resistant, reduced processing temperature, lead free, good electrical conduction and mechanical strength. The purpose of the present work is to investigate the aging behavior of MWCNT filled adhesives based on anhydride cured epoxy systems and their dependence on loading. Composites with different loadings of MWNT in epoxy and epoxy: heloxy are prepared and then stencil printed onto different surface finished boards like gold, silver and tin to prepare contact resistance samples and onto aluminum oxide boards to prepare volume resistivity samples. These samples are kept at room temperature for about 90 days and then placed in a temperature chamber to observe the behavior of these samples after accelerated aging. The readings are taken for as prepared samples, after 45 days, after 90 days and after accelerated aging. The results are summarized and different trends are observed for different loadings of MWNT, different combinations of epoxy: heloxy and for different surface finished boards.

Ledningsbanor syftar till att föra ström eller digitala signaler mellan elektroniska komponenter. Traditionellt brukar ledare av solid metall användas, då metall har låg resistans och lämpar sig bra som strömledare. I denna studie utforskas möjlig-heten för olika material att fungera som textila ledningsbanor. Textila ledningsba-nor behövs bland annat i medicinska plagg med sensorer. En ledningsbana som ska vara i ett plagg måste både vara tvättbar och flexibel. I denna studie har tre konduktiva garner testats; Bekinox VN 12/2*275 /175S, Shi-eldex 235/34 och Highflex 3981 7*1 Silver. Ett textilt band med fyra ledningsba-nor i, OHM-e-12-L-1, från företaget Ohmatex har också utvärderats samt har det undersökts om det är möjligt att använda konduktiv silikon, Elastosil LR 3162 A/B, som en ledningsbana. För att ta reda på hur de konduktiva materialen tål tvätt har tvättester utförts där resistansen efter tvätt har mätts. En metod har utvecklats som går ut på att undersöka om konduktiviteten försämras när materialet utsätts för mekaniskt deformation vid en böjrörelse. Det har även testats om en silikonbe-läggning med Dow Corning 3140 RTV Coating kan förhindra en eventuell höjning av resistansen efter testerna och resultaten har jämförts med de prover som inte varit belagda. Beläggningen isolerar även garnerna och därför har även det testats att använda Elastosil som kontaktpunkter för de belagda garnerna. Bekinox klarar både tvätt och böjningstest bra. Shieldex resistans höjs efter tvätt men silikonbeläggningen har en skyddande effekt. Shieldex klarar böjningstestet bra och resistansen ändras knappt. Highflex klarar tvättesterna och har väldigt låg resistans men är känslig mot mekanisk deformation och skadas i böjningstesterna. Där har inte beläggningen en skyddande effekt. Elastosil är inte lämplig som led-ningsbana och fungerar inte som kontaktpunkter. Elastosil visar sig däremot ha god härdighet mot både tvätt och böjning. Bandet från Ohmatex fungerar bra både efter tvätt och böjningstester och är lämplig som ledningsbana. / Interconnections are electrical conductive tracks that aim to transport electricity or digital signals between components in a circuit. The conventional way of doing this is to use connections of solid metal, since they have low electrical resistance and are thereby suitable conductors. In this study, different materials have been investigated for their suitability to be used as textile interconnections. Textile in-terconnections are needed in for instance medical measuring equipment garments. A textile interconnection in a garment needs to withstand washing and bending. In this study three conductive yarns are tested; Bekinox VN 12/2*275/175S, Shieldex 235/34 and Highflex 3981 7*1 Silver. A textile interconnection narrow fabric with four copper wires within, OHM-e-12-L-1, by the company Ohmatex has also been investigated. The conductive silicon Elastosil LR 3162 A/B has also been investigated for its suitability to fit as textile interconnection and as electrical contact with conductive yarns. Washing tests have been made to investigate how the materials electrical resistance is affected by washing. To measure and under-stand the materials flexibility and how the resistance is affected by bending of the material, the materials have been bended in a bending apparatus that has been developed in this study. It has also been investigated whether or not a silicon coat-ing, Dow Corning 3140 RTV Coating, of the yarns may protect them from the chemical and mechanical wearing of washing and bending. The change in re-sistance has then been compared to values of the uncoated yarns. Since the coat-ing is electrically isolating the yarns, screen printed contact points of Elastosil has been added and investigated. Bekinox withstands both washing and bending well. The electrical resistance of Shieldex increases by washing, but the silicon coated yarns increase less than the uncoated yarns. Shieldex withstands the bending test well and the change in re-sistance is low. Highflex passes the washing test well and has very low resistance. But the Highflex yarn is sensitive to mechanical deformation and gets damaged by the bending test. The silicon coating has no protecting effect here. Elastosil is not suitable as an interconnection and the contact points by Elastosil are neither working well together with the conductive yarns. But Elastosil do withstands both the washing and bending test well. The conductive narrow fabric by Ohmatex withstands both the washing and bending test well and it is suitable as an inter-connection.