Advancements in the semiconductor industry have lead to the miniaturization of components and increased power densities, resulting in thermal management issues. In response to this shift, finding multifunctional materials with excellent thermal conductivity and tailored electrical properties are becoming increasingly important. For this research thesis, three different studies were conducted to develop and characterize thermally conductive polymer composites. In the first study, a PPS matrix was combined with different types of carbon-based fillers to determine the effects of filler’s size, shape, and orientation on thermal conductivity. In the second study, effects of adding ceramic- and carbon- based fillers on the tailored thermal and electrical properties of composites were investigated. Lastly, the possibility of improving the thermal conductivity by introducing and aligning polymer fibers in the composites was investigated. The composites were characterized with respect to their physical, thermal, and electrical properties to propose possibilities of application in the electronic packaging industries.

Advancements in the semiconductor industry have lead to the miniaturization of components and increased power densities, resulting in thermal management issues. In response to this shift, finding multifunctional materials with excellent thermal conductivity and tailored electrical properties are becoming increasingly important. For this research thesis, three different studies were conducted to develop and characterize thermally conductive polymer composites. In the first study, a PPS matrix was combined with different types of carbon-based fillers to determine the effects of filler’s size, shape, and orientation on thermal conductivity. In the second study, effects of adding ceramic- and carbon- based fillers on the tailored thermal and electrical properties of composites were investigated. Lastly, the possibility of improving the thermal conductivity by introducing and aligning polymer fibers in the composites was investigated. The composites were characterized with respect to their physical, thermal, and electrical properties to propose possibilities of application in the electronic packaging industries.

The overall goal of this research is to develop ground-based technologies for disease detection and mapping which can maximize the effectiveness and efficiency of cotton root rot (CRR) treatments. Accurately mapping CRR could facilitate a much more economical solution than treating entire fields. Three cotton fields around CRR-prone areas of Texas have been the sites for three years of data collection. A complete soil apparent electrical conductivity (ECa) survey was conducted for each field with an EM38DD sensor. Multiple linear regression was used to relate physical and chemical soil properties to the ECa values obtained from the EM38DD. The variability in soil ECa measurements can be best accounted for using calcium carbonate levels as well as clay and sand contents in the soil. T-tests were used to determine that soil pH, clay, sand, and inorganic carbon content were significantly related to CRR incidence as determined by aerial images of each location. Spectral data were obtained for freshly picked cotton leaves from healthy, disease-stressed, and dying or dead plants using an ASD VisNIR spectroradiometer. The leaf spectra were evaluated using linear discriminant analysis (LDA), the receiver operator characteristic, and wavelet analysis to relate them to classifications of infection level. It was determined that healthy and infected leaves can be correctly classified 85% of the time based on the spectral data. The results from this study suggest that differences in soil characteristics may not be pronounced enough to accurately map CRR in the soil; however, the precision treatment of CRR may possible using an optoelectronic sensor to diagnose infected plants based on leaf reflectance.

SYNTHESIS, CHARACTERIZATION, AND ELECTRICAL PROPERTIES OF DIAZOPHENYLENE AND DIAZODIPHENYLENE BRIDGED Co, Ni, Cu, Ce, AND Er PHTHALOCYANINE POLYMERS Alkan, Cemil M. Sc., Department of Polymer Science and Technology Supervisor: Prof.Dr. Leyla Aras Co- Supervisor: Prof.Dr. G&uuml / ng&ouml / r G&uuml / nd&uuml / z September 2004, 112 pages In this research, diazophenylene and diazodiphenylene bridged metal-phthalocyanine polymers were produced from diazonium salt of diaminophenylene/bensidin and pre-synthesized tetraamino metal phthalocyanines. Tetraamino metal phthalocyanine complexes of Co, Ni, Cu, Ce, and Er were obtained by reducing tetranitro metal phthalocyanine complexes synthesized from 3-nitrophthalic anhydride, urea, metal salt, and ammonium molybdate catalyst. Complexes and polymers were characterized by Fourier Transform Infrared Radiation (FTIR) and UV-Visible spectroscopies. X-Ray analysis showed that there were short range orientations in the polymers. Thermal analysis of the complexes and the polymers were done by differential scanning calorimetry and thermal gravimetric analysis at a heating rate of 10&amp / #61616 / Cmin&amp / #61485 / 1 under nitrogen atmosphere. Ash analysis was performed to determine the metal content of the polymers. Viscosity and ebullioscopy measurements of the soluble part of the polymers were carried out in THF at 25&amp / #61616 / C. Scanning electron microscopy were used for morphology investigations of the polymers. Four probe conductivity measurements showed that electrical conductivity of the polymers increased according to the metallic conductivity of the metal at the center of the phthalocyanine units. When doped with iodine, the polymer samples showed 104 fold increase in their conductivities. Current-Voltage (I-V) measurements showed that the polymers were optically sensitive and semiconductors. Electrochemical analysis of the soluble part of the polymers were determined in tributylamine perchlorite+dichloromethane mixture utilizing cyclic voltammetry (CV).

Hydrate-bearing sediments may contribute to the availability of energy resources, affect climate change, or cause seafloor instability. The comprehensive study of hydrate-bearing sediments documented in this manuscript includes physicochemical aspects of hydrate nucleation near mineral surfaces, the validity of THF as a substitute guest molecule for the study of hydrate-bearing sediments, and the effects of hydrate formation on the electromagnetic and the mechanical properties of various soils with a wide range of specific surface. Natural marine sediments are included as part of this investigation to explore the effects of inherent fabric, salts, organic matter, and stress history on the geophysical properties of hydrate-bearing sediments. Experiments are designed to reproduce the state of effective stress in the field at the time of hydrate formation. A comprehensive set of instruments is deployed in this study, and the unprecedented development of electrical resistivity tomography for the study of hydrate formation and dissociation is also documented in detail. Results from this research have important implications for geophysical field characterization and monitoring processes such as production.

The present work investigates the effect of carbon nanotube (CNT) inclusions on the electrical and thermal conductivity of a thermoset epoxy resin. The characterization of electrical and thermal conductivity of CNT/epoxy composites is presented. Pristine, oxidized, and fluorine-functionalized unpurified CNT mixtures ("XD grade") were dispersed in an epoxy matrix, and the effect of stirring rate and pre-curing of the epoxy on the dispersion of the CNTs was evaluated. In order to characterize the dispersion of the CNTs at different length scales, Optical Microscopy (OM), Raman Spectroscopy, and Scanning Electron Microscopy (SEM) was performed. Samples of varying CNT weight fractions were fabricated in order to find the effect of CNT weight fraction on thermal and electrical conductivity. Electrical conductivity was measured using a dielectric spectrometer, and thermal conductivity was determined by a transient plane source thermal analyzer. It was found that electrical conductivity increases by orders of magnitude for the pristine and oxidized XD CNT composites relative to the neat epoxy matrix, while fluorinated XD CNT composites remain electrically non-conductive. A small, but significant, increase in thermal conductivity was observed for pristine, oxidized, and fluorinated XD CNT composites, showing a linear increase in thermal conductivity with increasing CNT weight fraction. Pristine XD CNTs were ball-milled for different times in order to reduce the degree of agglomeration and entanglement of CNTs, and composites were fabricated using the same technique as with non-milled XD CNTs. Using ball-milled CNTs shows improved dispersion but results in an electrically non-conductive composite at the CNT weight fractions tested. The thermal conductivity of the ball-milled CNT samples shows an initial increase higher than that of non-milled pristine, oxidized, and fluorinated XD CNTs, but remains constant with increasing CNT weight fraction. A micromechanics model based on the composite cylinders method was implemented to model the electrical and thermal conductivity of the CNT/epoxy composites. Nanoscale effects in electrical and thermal conduction, such as electron hopping and interface thermal resistance, respectively, were incorporated into the model in order to accurately predict the acquired results. Modeling results show good agreement with acquired experimental results.

With excellent electrical, thermal and mechanical properties as well as large specific surface area, graphene has been applied in next-generation nano-electronics, gas sensors, transparent electrical conductors, thermally conductive materials, and superior energy capacitors etc. Convenient and productive preparation of graphene is thereby especially important and strongly desired for its manifold applications. Chemically developed functionalized graphene from graphene oxide (GO) has significantly high productivity and low cost, however, toxic chemical reduction agents (e.g. hydrazine hydrate) and raised temperature (400-1100°C) are usually necessary in GO reduction yet not preferred in current technologies. Here, microwaves (MW) are applied to reduce the amount of graphene oxide (GO) at a relatively low temperature (~165°C). Experimental results indicate that resurgence of interconnected graphene-like domains contributes to a low sheet resistance with a high optical transparency after MW reduction, indicating the very high efficiency of MW in GO's reduction. Moreover, graphene is usually recumbent on solid substrates, while vertically aligned graphene architecture on solid substrate is rarely available and less studied. For TIMs, electrodes of ultracapacitors, etc, efficient heat dissipation and electrical conductance in normal direction of solid surfaces is strongly desired. In addition, large-volume heat dissipation requires a joint contribution of a large number of graphene sheets. Graphene sheets must be aligned in a large scale array in order to meet the requirements for TIM application. Here, thermally conductive fuctionalized multilayer graphene sheets (fMGs) are efficiently aligned in a large scale by vacuum filtration method at room temperature, as evidenced by SEM images and polarized Raman spectroscopy. A remarkably strong anisotropy in properties of aligned fMGs is observed. Moreover, VA-fMG TIMs are prepared by constructing a three-dimensional vertically aligned functionalized multilayer graphene architecture between contact Silicon/Silicon surfaces with pure Indium as a metallic medium. Compared with their counterpart from recumbent A-fMGs, VA-fMG TIMs have significantly higher equivalent thermal conductivity and lower contact thermal resistance. Electrical and thermal conductivities of polymer composite are also greatly interested here. Previous researches indicated that filler loading, morphology of fillers, and chemical bonding across filler/polymer interfaces have significant influence on electrical/thermal conductivity of polymer composite. Therefore, the research also pays substantial attention to these issues. First, electrical resistivity of CPCs is highly sensitive on volume or weight ratio (filler loading) of conductive fillers in polymer matrix, especially when filler loading is close to percolation threshold (pc). Thermal oxidation aging usually can cause a significant weight loss of polymer matrix in a CPC system, resulting in a filler loading change which can be exhibited by a prompt alteration in electrical resistivity of CPCs. Here, the phenomena are applied as approach for in-situ monitoring thermal oxidation status of polymeric materials is developed based on an electrical sensors based on conductive polymeric composites (CPCs). The study developed a model for electrical resistivity of sensors from the CPCs as a function of aging time at constant aging temperature, which is in a good agreement with a Boltzmann-Sigmoidal equation. Based on the finding, the sensors show their capability of in-situ in-situ monitor and estimate aging status of polymeric components by a fast and convenient electrical resistance measurement. Second, interfacial issues related to these thermal conductive fillers are systemically studied. On the one hand, the study focuses on relationship between morphology of h-BN particles and thermal conductivity of their epoxy composites. It is found that spherical-agglomeration of h-BN particles can significantly enhance thermal conductivity of epoxy resin, compared with dispersed h-BN plates, by substantially reducing specific interfacial area between h-BN and epoxy resin. On the other hand, surface of high thermal conductive fillers such as SiC particles and MWNTs are successfully functionalized, which makes their surface reactive with bisphenol A diglycidyl ether and able to form chemical bonding between fillers and epoxy resin. By this means, thermal conductivity of polymer composites is found to be significantly enhanced compared with control samples, indicating the interfacial chemical bonding across interface between thermal conductive fillers and polymer matrix can promote heat dissipation in polymeric composites. The finding can benefit a development of high thermal conductive polymer composites by interfacial chemical bonding enhancement to meet the demanding requirements in current fine pitch and Cu/low k technology.

Thesis (M.S.)--University of Wisconsin--Madison, 1974. / Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Σκοπός της παρούσας διπλωματικής εργασίας είναι η μελέτη της συμπεριφοράς συνθέτων υλικών με τροποποιημένη πολυμερή μήτρα σε υγροθερμικές συνθήκες κόπωσης. Συγκεκριμένα τα υλικά που χρησιμοποιήθηκαν είναι CFRP (Carbon Fiber Reinforced Polymers), δηλαδή σύνθετα υλικά πολυμερικής μήτρας, τα οποία είναι ενισχυμένα με ίνες άνθρακα. Πρέπει να σημειωθεί ότι χρησιμοποιήθηκαν δυο τύποι πολυμερικών συστημάτων. Το πρώτο σύστημα αποτελείται από την εποξειδική ρητίνη LY 564 και τον σκληρυντή Aradur 2954, ενώ το δεύτερο σύστημα αποτελείται από την κυανεστερική ρητίνη Primaset και το σκληρυντή DT-4000. Επίσης και στα δυο συστήματα τα υλικά που κατασκευάστηκαν ήταν μονο-διεύθυντα (UD προς μία διεύθυνση 00), με εξαίρεση ότι στο εποξειδικό σύστημα κατασκευάστηκαν και Quasi υλικά, στο οποίο οι ίνες έχουν προσανατολισμό σε τέσσερις διαφορετικές διεθύνσεις [(0/+45/-45/90)2]s. Όλα τα υλικά περιέχουν συνολικά 16 στρώσεις ινών. Ακόμη η μήτρα των υλικών μας είναι τροποποιημένη, καθώς περιέχει CNTs (Carbon Nano Tubes) νανοσωληνίσκους, σε διαφορετικά ποσοστά. Τα ποσοστά που μελετήθηκαν ήταν 0%, 0,1%, 0,5% και 1% CNTs για τα εποξειδικά UD υλικά, 0% CNTs για τα Quasi και τέλος 0%,0,5% και 1% CNTs για το κυανεστερικό σύστημα. Τα συγκεκριμένα υλικά τοποθετήθηκαν σε ειδικό μπάνιο για 60 ημέρες, που ήταν γεμάτο με απιονισμένο νερό και σε θερμοκρασία 800C. Μελετήθηκε συστηματικά η απορρόφηση υγρασίας μέχρι και τον κορεσμό τους, καθώς και η μεταβολή της ηλεκτρικής αντίστασης των υλικών αυτών. Ακόμη μετά από 60 ημέρες και αφού τα υλικά βγήκαν από το μπάνιο τοποθετήθηκαν σε φούρνο θερμοκρασίας 800C. Σκοπός της διαδικασίας αυτής ήταν η ξήρανση τους, καθώς και η μέτρηση του χρόνου που απαιτείται για την διαδικασία αυτή. Έγιναν επίσης πειράματα δυναμικής-μηχανικής ανάλυσης (DMA), για την μέλετη της μεταβολής της θερμοκρασίας υαλώδους μετάβασης (Tg) για όλα τα στάδια. Αρχικά έγιναν πειράματα DMA σε όλα τα δοκίμια πρίν τοποθετηθούν στο μπάνιο, στην συνέχεια μετά το στάδιο του κορεσμού τους (περίπου στις 20 ημέρες παραμονής τους στο μπανιο), στις 60 ημέρες παραμονής των δοκιμίων στο νερό και τελικά μετά την διασικασία της ξήρανσης. Τέλος έγιναν πειράματα διηλεκτρικής φασματοσκοπίας για να καθοριστεί η ηλεκτρική αγωγιμότητα σε δοκίμια πριν τοποθετηθούν στο μπάνιο, κατά την διάρκεια του κορεσμού τους και τέλος μετά την ξήρανσή τους. / --

The surface mining method of mountaintop removal has been shown to adversely affect the water quality and hydrologic characteristics of downstream regions. Based on recent scientific literature, the U.S. EPA issued guidance on the specific conductivity (EC25ºC) of waters discharged from mined lands in the Appalachian Coal Belt Region stating that these waters should have an EC25ºC less than 300-500 μS cm-1. Hence, accurately measuring EC25ºC levels of mine discharged waters has significant implications. Furthermore, the development of reclamation techniques that positively impact the hydrological and water quality aspects of valley fill (VF) discharge is needed. To tackle these questions, a two-part study was conducted. First, a detailed study comparing sensor performance under controlled and field conditions was performed. Second, the hydrologic parameters (storm flow only) of a stream restoration project constructed atop a retrofitted valley fill were compared to a headwater stream with no mining as well as one influenced by mining with no restoration. Results indicated that significant differences were noted between four conductivity sensors with errors positively correlated with increases in EC25ºC. For storm events, the restored stream section atop the VF is performing similar to the unminded, forested watershed for some hydrologic parameters.