Search

Methods for exfoliating materials down to atomically thin planes have been revolutionary in scientific research and industrial applications. Such methods can be used to exfoliate materials in a solution and then reconstruct the exfoliated nanosheets into flexible thin laminate films with advantageous properties. Reconstructed laminates of exfoliated 2D materials are particularly applicable for thermoelectric applications, converting between thermal and electrical energies. Flexible laminates of bulk high-performance thermoelectric materials can recover waste heat from ubiquitous sources. In this way, body heat, which would otherwise be lost to the surroundings, becomes a recoverable power source, enabling a future with self powered, energy-autonomous and connected wearable electronics. In this study, state-of-the-art brittle bulk thermoelectrics were reconstructed into flexible energy recovery devices. A single module, consisting of two different elements demonstrated a recovery power density of 0.65 mW/cm^2 and peak output power of 1.95 uW across a 30 C thermal difference. The addition of more modules increased the overall recovery. These methods demonstrate a scalable, low-temperature and solution-processable method of retaining high thermoelectric performance in a flexible form factor that allows for simple scaling of thermal energy recovery. Exfoliation methods were also used to create graphene paper samples with annealing temperature-dependent thermoelectric properties. The resultant laminates were arranged into a highly sensitive thermocouple temperature sensor comparable to conventionally used wire variants. These flexible graphene paper thermocouples have potential applications in conformal temperature measurements above 1,000 C in industrial machinery, amongst other uses. Due to their large specific surface area, the measurement of the thermal properties of high thermal conductivity thin laminate films is often challenging. Here, a self-heating 3-omega thermal property measurement system was devised. Based on methods to measure thermal properties in wires, an adapted methodology, suited for thin laminate films, was achieved. Experimental requirements were rigorously defined and measurement sample geometries were comprehensively improved, leading to optimum thermal property measurements. Each of the explored areas, all concerning the thermal, electrical and thermoelectrical properties of thin laminate films of 2D materials, demonstrated numerous characterisation techniques and exceptional material properties, stimulating many further avenues for improvements and applications.

This study seeks to develop smart hydrogel formulations for injectable controlled drug delivery from Pluronics to enhance patients compliance, decrease side effects, reduce dose and frequency. A biocompatible copolymer, Pluronic F127 was probed as the main ingredient for the injectable systems owing its low gelation concentration and ease of modification the system properties through excipients addition. The matrix properties were studied through a series of thermal, rheological and structural (SAXS/SANS) experiments as a function of concentration and shear rate, covering both static and dynamic environments. It has shown that gelled viscosity (and structure) can be critically controlled by shear rate and the structures recorded do not match those predicted for sheared colloids. Two further Pluronics F68 and F108, were studied showing similar but shifted gelation properties to F127. Effects of additives were studied by introducing different Mw PEGs and a model hydrophobic drug 'ibuprofen' to a F127 20% formulation. PEGs addition effects on the system properties and gelation transition were largely dependent on the Mw used in the blend, which became more prominent with increasing chain length. Ibuprofen's addition has resulted in reduced gelation temperature and smaller hard spheres without having a great effect on the system rheological properties compared to neat gels. Blends containing both additives PEG and ibuprofen exhibited a synergistic effect, where comparisons show that Ibuprofen had the largest effect on the blends lowering gelation boundaries and slightly increasing the size of the hard spheres indicating the necessity of full characterisation of the formulation with any API.

Structural applications, including aircraft, ships, and offshore oil drilling platforms, have witnessed a surge in composite material usage. However, exposure to elevated temperatures poses a significant risk to these materials, especially in scenarios such as fires and high-temperature exhaust gas impingement. Despite limited or no visible damage, composite properties can undergo significant degradation, leading to potential in-service failures and jeopardizing operational safety and integrity. It was previously determined that the accuracy of the equipment and methodology used for measuring elevated temperature thermal properties, particularly in predicting composite material thermal properties could not meet the necessary precision. Using an inverse analysis technique to solve for the thermal conductivity and specific heat capacity, the thermal properties of composite materials can be determined. These thermal properties can then be used in a rapid heat damage assessment and failure prediction tool that can be updated based on additional data provided during inspection which takes into account material state changes and damage development due to the elevated temperature exposure and provides a way to incorporate those changes into subsequent structural analyses.

This thesis focuses on fire resistance of 19th century cast iron framed structures. Based on material property data obtained from a comprehensive literature review, upper and lower bound relationships of the thermal and mechanical properties of 19th century fireproof floor construction materials have been derived. Because these materials have large variability, a sensitivity analysis has been undertaken to investigate the most effective ways of representing such variability. The sensitivity analysis has indicated that the elevated mechanical properties of cast iron should be reliably quantified. The thermal expansion of cast iron can be taken as equal to that of steel as in EN1993-1-2. Variabilities in other material properties have modest effects on fire resistance of cast iron structures and can be safely modeled according the Eurocode material models for similar modern materials (using thermal properties of modern steel for cast iron, using thermal properties of modern concrete for the insulation materials of cast iron structures). In order to resolve some of the uncertainties in mechanical properties of cast iron at elevated temperatures, a total of 135 elevated temperature tests have been performed, including tension and compression tests, transient state and steady state tests, tests after cooling down and thermal expansion tests. These test results have been used to establish the elevated temperature stress-strain-temperature relationships in tension and compression. Afterwards, calculation methods are developed to calculate the bending resistance of cast iron beams and compression resistance of cast iron columns at elevated temperatures. For cast iron beams, a fibre model has been developed to calculate elevated temperature moment capacity of cast iron beams in jack arch construction, taking into consideration non-uniform temperature distributions in the cross-section. The fibre model divides the cross section into a large number of fine layers and for a given curvature and neutral axis position calculates the strain, the temperature, the stress and the force of each layer. It has been found that under historically applied load, the fire resistance of such beams can be 60 minutes or higher. The Monte Carlo simulation method has been used to take into account the variabilities of important mechanical properties of cast iron at elevated temperatures; Young’s modulus, 0.2% proof stress, ultimate strength, corresponding strain at ultimate strength and failure strain in tension and Young’s modulus, proportional limit and 0.2% proof stress in compression. This has enabled material safety factors of 1.50, 2.50, 4.50 and 5.50 to be proposed for target failure probabilities of 10-1, 10-2, 10-3 and 10-4 respectively. For cast iron columns, a finite element model, built using the commercial software ABAQUS, has been used to examine the effects of changing different design parameters (column slenderness, member imperfection, cross section imperfection, degree of axial restraint, load factor and load eccentricity) on fire resistance of cast iron columns. Validation of the finite element model was by comparison of the simulation results against six fire resistance tests, three on unprotected and three on protected cast iron columns. The results of this numerical parametric study indicate that the fire resistance of cast iron columns is generally higher than that of modern steel columns because the applied loads on cast iron columns are lower and cast iron columns have thicker sections than modern steel columns. Comparison of the numerical parametric study results with the calculation results using the steel column design method in EN1993-1-2 has found that the EN 1993-1-2 calculation results are generally on the safe side.

Tooling design is crucial for the production of cost-effective and durable composite products. As part of the current search for cost reduction (by reducing capital investment, energy use and cycle time), integrally-heated tooling is one of the technologies available for ‘out-of-autoclave’ processing of advanced thermoset polymer composites. Despite their advantages, integrally-heated tools can suffer from uneven distribution of temperature, variability in heat flow rate and inconsistency in heating/cooling time. This research, therefore, investigates a number of design variables such as shape and layout of heating channels in order to improve the heating performance of an integrally-heated tool. Design of Experiments (DoE) has been carried out using Taguchi’s Orthogonal Array (OA) method to set several combinations of design parameters. Each of these design combinations has been evaluated through numerical simulation to investigate heating time and mould surface temperature variation. The simulation results suggest that the layout of the channels and their separation play a vital role in the heating performance. Signal-to-Noise (S/N) ratio and analysis of variance (ANOVA) have been applied to the results obtained to identify the optimal design combination of the integrally-heated tool. Statistical analysis reveals that the heating performance of an integrally-heated tool can be significantly improved when the channels’ layout is parallel. The shape of the channels has negligible effect and the distance between the channels should be determined based on the production requirement. According to the predicted optimal design, a developed integrally water-heated tool is manufactured. The actual thermal properties of the constituent materials of the produced tool are also measured. Then a numerical model of the experimental tool model is simulated in ANSYS software, with setting the actual material properties and boundary condition to define the temperature uniformity and heating rate of the experimental tool. Comparison of the experimental and numerical results of the experimental tool confirmed the well assigning of the boundary conditions and material properties during simulation the heated tool. The experimental results also confirmed the predicted optimal design of the integrally heated tool. Finally, in order to define its thermomechanical behaviour under the effective (in service) thermal loads, a tool model is simulated. Numerical results presented that the produced extremes of thermal deformation, elastic strain, normal and plane shear stresses, under the effective thermal loading, are within the allowable elastic limits of the participated materials.

Highly extent exfoliated and intercalated silicone rubber (SR) nanocomposites based on natural montmorillonite (Cloisite Na+) and organically modified montmorillonite (Cloisite 30B and Cloisite 20A) were successfully prepared by melt-mixing technique. As indicated by the X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis, intercalation and exfoliation of the clay particles in the nanocomposites was achieved at less than 8 parts per hundred (phr) rubber by weight, irrespective of the initial interlayer spacing of the nanoclay particles. Cloisite 30B was spontaneously transformed into exfoliated nanostructures during the vulcanisation stage as suggested by X-ray diffraction (XRD), fourier transforms infra-red spectroscopy (FTIR) and differential scanning calorimeter (DSC) results. Overall, the use of the nanoclays in silicone rubber improved the Young's modulus, tensile strength and elongation at break by more than 50% as compared to the neat SR. However, the Cloisite Na+yielded outstanding mechanical properties with low hysteresis at the same loading of the exfoliated Cloisite 30B and intercalated Cloisite 20A organoclays, even though the filler had a tendency to produce mixture intercalated/exfoliated nanostructures in the SR matrix. It was concluded that the tensile strength and Young's modulus in this particular rubber nanocomposite are dominated bythe degree of crosslink density instead of filler dispersion. In addition, incorporation of the nanoclays in SR altered the wear mechanism of silicone rubber where addition of the fillers minimised the weight loss during abrasion testing, particularly at low filler loading (< 6phr). Moreover, this study showed that the SR/C30B nanocomposite exhibited excellent heat resistance in comparison to the other two nanocomposites and neat SR as revealed by higher retention strength. The thermal stability of the rubber in air was strongly dependent on the clay morphology and increased in the following order: highly intercalated/exfoliated SR/Na+MMT < highly intercalated SR/C20A < highly exfoliated SR/C30B. Furthermore, the performance of SR Abstractiiinanocomposites containing precipitated silica (PS)/montmorillonite (MMT) hybrid fillers were investigated as a function of PS/MMT hybrid filler weight ratio. Interestingly, the stress-strain properties of the nanocomposites with the hybrid fillers showed a large improvement at high deformation in comparison with the properties of those nanocomposites containing the PS and MMT fillers. The resistance to ageing of SR/PS/MMT was improved by gradually adding amounts of PS filler into the PS/MMT hybrid filler system. Finally, the comparative study demonstrated that the SR containing precipitated silica (PS)/multiwall carbon nanotube (MWMT) hybrid filler significantly improved stiffness of the rubber but accompanied by a small improvement in the tensile strength and elongation at breakwith regard to the SR/PS/MMT. In spite of that, the inclusion of PS/MWNT gave adverse effects to the cure efficiency of the SR compounds which is a drawback from processing point of view.

The majority of therapeutic pharmaceutical formulations are presented in the solid form. Moisture is able to play an important role in the functional performance of pharmaceutical solids. Moisture profiling is able to provide novel information with regards to the behaviour of moisture within materials using equilibrium relative humidity as a measurement. The hypothesis investigated explores the changes in equilibrium relative humidity of pharmaceutical material induced by physical, chemical or storage conditions, these are able to be monitored using the innovative moisture profiler system. The aims within this were to primarily validate the moisture profiler and secondly evaluate the effects of moisture on physical forms and with respect to effects of compaction, finally this was compared to conventional characterisation methods. Preliminary explorations were conducted in order to assess the validity of the moisture profiler, from this lactose was selected as a suitable pharmaceutical material for further work. Processing effects were then examined, firstly storage at elevated relative humidity of different forms of lactose were explored, and this was carried out with supplementary analysis. Secondly the effects of tabletting were explored, different compaction forces were investigated to observe if this had any notable effects on equilibrium relative humidity of the different lactose forms. Finally subsequent storage of the compacts were examined in order to explore if there were any changes in the equilibrium relative humidity.

LFC is cementatious material integrated with mechanically entrained foam in the mortar slurry which can produce a variety of densities ranging from 400 to 1600 kg/m3. The application of LFC has been primarily as a filler material in civil engineering works. This research explores the potential of using LFC in building construction, as non-load-bearing partitions of lightweight load-bearing structural members. Experimental and analytical studies will be undertaken to develop quantification models to obtain thermal and mechanical properties of LFC at ambient and elevated temperatures. In order to develop thermal property model, LFC is treated as a porous material and the effects of radiant heat transfer within the pores are included. The thermal conductivity model results are in very good agreement with the experimental results obtained from the guarded hot plate tests and with inverse analysis of LFC slabs heated from one side. Extensive compression and bending tests at elevated temperatures were performed for LFC densities of 650 and 1000 kg/m3 to obtain the mechanical properties of unstressed LFC. The test results indicate that the porosity of LFC is mainly a function of density and changes little at different temperatures. The reduction in strength and stiffness of LFC at high temperatures can be predicted using the mechanical property models for normal weight concrete provided that the LFC is based on ordinary Portland cement. Although LFC mechanical properties are low in comparison to normal weight concrete, LFC may be used as partition or light load-bearing walls in a low rise residential construction. To confirm this, structural tests were performed on a composite walling system consisting of two outer skins of profiled thin-walled steel sheeting with LFC core under axial compression, for steel sheeting thicknesses of 0.4mm and 0.8mm correspondingly. Using these test results, analytical models are developed to calculate the maximum load-bearing capacity of the composite walling, taking into consideration the local buckling effect of the steel sheeting and profiled shape of the LFC core. The results of a preliminary feasibility study indicate that LFC can achieve very good thermal insulation performance for fire resistance. A single layer of 650 kg/m3 density LFC panel of about 21 mm would be able to attain 30 minutes of standard fire resistance rating, which is comparable to gypsum plasterboard. The results of a feasibility study on structural performance of a composite walling system indicates that the proposed panel system, using 100mm LFC core and 0.4mm steel sheeting, has sufficient load carrying capacity to be used in low-rise residential construction up to four-storeys.

This thesis explores the impact of different modifiers on the phase-changing properties and performance grade of asphalt binders at high and intermediate temperatures. The primary focus is on understanding how phase-changing materials (PCMs) like Styrene-Butadiene-Styrene (SBS), Lignin, and Ground Tire Rubber (GTR) influence the physical, chemical, and performance characteristics of asphalt binders, aiming to enhance their durability against temperature-induced stresses such as rutting and thermal cracking and make a correlation between phase changing properties and performance grade. This study utilizes two base asphalt binders, PG 64-22 and PG 76-22, and modifies the binder with SBS, Lignin, and GTR. Through an extensive experimental setup involving aging processes (Rolling Thin Film Oven (RTFO) and Pressure Aging Vessel (PAV)) and a series of both traditional and advanced tests (including Dynamic Shear Rheometer, Rotational Viscometer, Fourier Transform Infrared Spectroscopy, and others), a comprehensive dataset of 51 samples is analyzed. The research findings demonstrate a significant impact of the modifiers on the rheological and thermal properties of the asphalt binders. Notably, modifiers like SBS significantly improve the resistance to rutting and thermal cracking, indicating their potential to extend the lifespan of asphalt pavements. Moreover, the study underscores the correlation between the phase-changing properties (specific heat and heat of combustion) and the performance grade of the asphalt binders, suggesting a novel approach to asphalt pavement design that considers thermal energy storage and transfer capabilities. By establishing a correlation between phase-changing properties and performance grades, the research offers valuable insights for developing more durable and climate-resilient asphalt pavements, underscoring the importance of selecting appropriate modifiers based on their thermal and rheological benefits.

Consumer demands for ethically sourced and environmentally friendly food products have led to development efforts to replace animal-based proteins with plant-based alternatives. However, plant-based protein ingredients can be limited by their functional and sensory properties, and thus processing techniques to improve these properties must be explored. Enzymatic hydrolysis has been suggested to improve key functional properties, such as solubility, but the research methodology in this area is questionable and hydrolysis does not fully address sensory deficits in plant-protein ingredients, notably bitterness. In this dissertation, commercial extruded snack products containing soy protein hydrolysates were used as a model to quantify bitterness and test the viability of reformulation with flavor maskers or alternatively processed proteins to improve off-flavor. This study revealed that commercial flavor maskers are not effective at reducing bitterness in products containing soy hydrolysate, but soy protein hydrolysates made by different manufacturers with different processing methods proved a viable replacement with improved off-flavor. In search for conclusive evidence that enzymatic hydrolysis results in improved functionality, a review of literature was conducted. This review concluded that enzymatic hydrolysis process may result in the formation of insoluble aggregates, which in most studies are removed by centrifugation or filtration during processing, thus artificially increasing the reported solubility values for plant-protein hydrolysates. The phenomenon of hydrolysis induced aggregation was confirmed for protein isolates from soy and as well as a pulse protein alternative to soy, chickpea, which were hydrolyzed by Flavourzyme and Alcalase. Analysis of physical and structural properties of the hydrolyzed proteins revealed that hydrolysis led to protein destabilization, causing hydrogen-bond mediated aggregation during thermal enzyme inactivation. The knowledge of formation of insoluble material during hydrolysis led to consideration of whether those large aggregates had desirable functional properties, and if the functional properties of the hydrolysates differed by the size of the protein fragments formed. Additionally, the evidence of molecular weight dependence on peptide bitterness also suggested that separations of hydrolysates by size may help sequester bitter compounds, thus increasing consumer acceptability. Alcalase hydrolysates of chickpea protein separated by centrifugation and ultrafiltration into insoluble, >10 kDa, 5-10 kDa, and 10 k Da and 5-10 kDa fractions had improved solubility, oil binding, foaming, and emulsifying properties compared to the unhydrolyzed protein and unfractionated hydrolysate, while the insoluble fraction had universally low functionality. Sensory analysis of hydrolysate fractions concluded that the most highly functional fractions, >10 kDa, and the unfractionated hydrolysate had the highest bitterness levels, while the unhydrolyzed protein, insoluble fraction, and 10 kDa peptide fractions. While their formation is contradictory to previously reported results, hydrolysis induced aggregates may be useful as texturized plant-based proteins for meat and dairy alternatives which do not require high solubility. The use of hydrolysate fractionation highlights the dependence of hydrolysate functionality and sensory characteristics on the ingredient processing and demonstrates the potential of creating multiple novel value-added ingredients from a single source. Overall, enzymatic hydrolysis of soy and chickpea proteins show promise as a means to create functional alternatives to animal-based proteins for a variety of applications, while more work is required to address the bitterness associated with highly functional fractions.

1 were achieved when testing specimens and this rate was obtained using a split Hopkinson pressure bar. A substantial number of preliminary tests were conducted in order to obtain a suitable specimen size which was then used in the temperature measurement process. Quasistatic, intermediate and high strain-rate tests were performed; the last utilised the radiometer for temperature measurement. An Eyring plot was constructed from which fundamental values for activation volumes and enthalpies were obtained. Full descriptions of the testing techniques used have been included and a brief photoelastic analysis has been carried out on a partially deformed specimen which shows molecular alignment.

Bituminous coal was utilized as a particulate filler in polymer-based composites to fabricate standard 1.75 mm coal-plastic composite filaments for use in commercially available fused deposition modeling 3D printers. The composites were formulated by incorporating Pittsburgh No. 8 coal into polylactic acid, polyethylene terephthalate glycol, high-density polyethylene, and polyamide-12 resins with loadings ranging from 20 wt.% to 70 wt.%. CPC filaments were extruded and printed using the same processing parameters as the respective neat plastics. All coal-plastic composite filaments exhibited uniform particle dispersion throughout the microstructure. The mechanical properties of the 3D printed composites were characterized and compared to composites fabricated using traditional compression molding. Tensile and flexural moduli as well as hardness had direct proportionality with increasing coal content while flexural strength, tensile strength, and impact resistance decreased for most composite formulations. Interestingly, polyamide-based composites demonstrated greater maximum tensile and flexural strengths than unfilled plastic. Microscopy of as-fractured samples revealed that particle pull-out and particle fracture were the predominant modes of composite failure. The introduction of coal reduced the coefficient of thermal expansion of the composites, ameliorating the warping problem of 3D printed high-density polyethylene and allowing for additive manufacturing of an inexpensive and widely available thermoplastic. The high-density polyethylene composites demonstrated increased heat deflection temperatures, but all composites maintained comparable glass and metal transition temperatures, allowing them to be processed with commercial 3D printer extruders. The composites exhibited decreased specific heat capacities suggesting lower energy requirements for processing the material. Coal reduced the composite thermal conductivities compared to the neat plastics but improved the thermal stability of the polymers. This work establishes the foundation for the additive manufacturing of novel, sustainable coal-plastic composites for future technology scaling and industrial adoption.

Emerging technologies in high-temperature applications are often limited by operation temperatures of structural and coating materials. Key factors determining material feasibility include phase stability, low thermal conductivity, high oxidation and corrosion resistance, and high mechanical strength. While many structural effects impact thermal transport in ceramic materials, two crucial aspects of thermal transport are grain boundaries/crystal interfaces and point defects. Interfaces and point defects such as substitutional atoms cause phonon scattering and act as thermal resistors to inhibit heat transport. The resistance due to grain boundaries and interfaces is known as the Kapitza resistance. A better understanding of how grain boundary interfaces and point defects impact thermal transport can help to predict the performance of novel ceramic oxide materials. The goals of this dissertation are to (1) evaluate the effectiveness of using a relatively new technique, three-omega, to study the impact of composition and structure on the thermal conductivity of ceramic oxides; (2) to understand the phase formation and stability of high entropy zirconate ceramic oxides; and (3) to evaluate compositionally complex monazite structure ceramic oxides with significant size variations of rare earth cations within the lattice. The first study outlines the design processes and limitations of the three omega systems for ceramic oxide systems. Low-temperature measurements of single-phase and multiphase oxides are compared to reported literature and measurements obtained using laser flash analysis. Although this study demonstrates the wide variation within thermal conductivities reported for specific compositions, the three-omega method is a valuable screening tool for evaluating the thermal conductivity of novel ceramic oxides. The second study evaluates the phase formation of conventionally sintered high entropy zirconates ((5RE1/5)2Zr2O7 and (6RE1/6)2Zr2O7) with significant variations in the Rare Earth (RE) cation size to stabilize in the pyrochlore crystal structure. The final study focuses on the synthesis and phase evolution of high entropy monazite ((5RE1/5)PO4 and (6RE1/6)PO4) with large variations in the (RE) cation size and the phase. For both studies, the phase composition and the extent of mixing are investigated via electron microscopy with energy dispersive x-ray spectroscopy and x-ray diffraction, evaluating the stability of structures with the inclusion of elements that are not stable in the pyrochlore (zirconates) and monazite (phosphates) crystal structures. Through the investigation of novel compositionally complex or high-entropy systems, this study aims to introduce high-temperature ceramic oxides with enhanced thermal properties that will direct future research towards materials that surpass the limiting factors in materials used in extreme environment engineering applications.

Experiments are described in which the momentum flux of gas atoms, remitted normal to the surface of a hot clean tungsten ribbon immersed in a low pressure of helium or argon, is measured with a torsion balance and the thermal accommodation coefficient deduced. Data are presented in which the tungsten temperature range was 700 to 1900 K for helium and 1100 to 1700 K for argon. If it is assumed that the normal remitted momentum flux is that expected on assumption of the cosine emission relation, accommodation coefficients much larger (and for argon physically impossible) than those found previously by other workers are implied. A model is proposed which assumes that atoms impinging on and remitted from the hot tungsten ribbon conserve momentum in directions parallel to the surface. This results in a remitted flux, in the direction of the normal, greater than the cosine relation would predict. The resulting accommodation coefficients are then of the same order as those found using the total heat loss method. The method here reported is believed to be novel. Its accuracy increases with the temperature of the hot solid. It permits the measurement of translational thermal accommodation without relying on the temperature coefficient of resistance of the solid and hence is applicable to alloys and to non-metals. For metals., which have a normal temperature coefficient of resistance, the method allows translational accommodation to be measured and internal energy accommodation to be deduced.

Theories of the metal-electrolyte interface are reviewed with particular attention to the prediction of thermodynamic quantities. A comparison of the different theories is made using a range of experimental results on Hg-aqueous electrolyte systems. Certain widespread failings of the models are revealed. These are identi- fied as being the results of a neglect of solvent structure and of chemical interactions. Next a solvent-free metal-molten salt system is investigated using a model based on the MSA. Thermodynamic properties, parti- cularly the capacitance and the potential at the point of zero charge and their variation with temperature, are calculated. The magnitudes for a range of ionic species are in agreement with experiments for Pb-alkali halide systems, but the (relatively weak) temperature dependence is not predicted correctly. The success of this application of the MSA compared to applications to aqueous systems shows the great importance of the solvent in determining the properties of these systems. To attempt to improve on the MSA model a new model based on the EXP approximation is developed. The predicted trend of the temperature dependence of capacitance is now given correctly but in other respects the predictions are worse than those of the MSA. In our first MSA model the metal is treated as a hard wall. A more realistic representation is now introduced which incorporates electron spill-out. By a phenomenological analysis the extent of spill-out into the electrolyte is estimated. No direct measurement of this quantity has been made. It is consistent with theoretical estimates made for aqueous systems when allowance ,is made for the effect of the solvent.

Abstract: Canada has approximately 50% of land mass covered with permafrost. With the increasing of mining and construction activities in permafrost regions, cement-based mixtures (e.g., concrete, shotcrete, backfill, and grout) are expected to be increasingly used in these regions. However, cold temperature (< 5 ºC) causes the slow strength development of cement-based mixtures, which is unfavorable since it decreases construction efficiency, increases costs, and raises safety issues. In addition, early-age frost damage may happen if cement-based mixtures could not gain sufficient strength (compressive strength 3.5 MPa) before getting frozen. Once early-age frost damage happens, the strength of cement-based mixtures cannot be ensured to reach an adequate value even if it is re-cured at normal temperatures (e.g., 20 °C), which is also unsafe. In response these issues, this Ph.D. program aims to develop calcium sulfoaluminate (CSA) cement-based mixtures for permafrost region applications. Experiments were conducted to investigate the hydration reaction, strength development, resistance to early-age frost damage, and thermal properties (e.g., thermal conductivity, diffusivity, and heat capacity). A numerical model was developed to predict the temperature profiles in hardening CSA cement-based mixtures. The results show that the hydration reaction and the strength development of CSA-based mortar were much faster than Portland cement-based mortar at cold temperatures (< 5 °C). For example, CSA cement-based mortar cured at -10 °C achieved a UCS of 15.5 MPa at 1 day, while OPC-based mortars almost have no strength developed at 28 days. CSA cement-based mixtures also showed high resistance to early-age frost damage owing to the fast strength development. After re-curing, CSA cement-based mortar that had exposed to -10 °C reached 117.8% of the UCS of the same mixtures directly cured at 23 °C, while the data for OPC-based mortars with and without antifreeze admixture (calcium nitrate) were 56.0% and 45.1%, respectively. In addition, the thermal conductivity of 28-day CSA cement-based mortars reduced from 0.97 W/m·K to 0.57 W/m·K, 0.29 W/m·K, and 0.13 W/m·K when 30%, 60%, and 100% volume of aggregates were replaced with expanded perlite. These CSA cement-based thermo-insulting mortars are expected to not only provide mechanical support, but also work as thermal insulation materials for mitigating the heat exchange among permafrost, cement-based mixtures, and air. At last, the developed numerical model was validated by comparing the modeled temperature profiles with experimentally measured temperature profiles in hardening CSA cement samples. After validation, the influence of curing temperature, curing modes (e.g., curing in permafrost or curing in cold air), and sample sizes on the temperature profiles of hardening CSA cement mixtures was investigated and compared with that on an OPC-based mixture. The results suggest that samples should be cured in cold soil or sand when investigating the performance of cement-based mixtures used in permafrost regions since the different curing modes caused a large influence on the temperature profiles of hardening cement-based mixtures. The temperature gradient in CSA-based sample was more significant than that in OPC-based sample. Precautions are needed to control the thermal cracks when CSA cement-based mixtures are used in cold temperatures, even if the structure size is small (e.g., Ø300×600mm). Overall, this thesis developed CSA cement mixtures that can achieve fast strength development and have high resistance to early-age frost damage for permafrost region applications. The findings provide a new solution to accelerate strength development and prevent early-age frost damage when cement-based mixtures are applied in permafrost regions.

Abstract: Polymers have various attractive properties (e.g., low volume mass density, low cost and excellent degradation resistance), and hence, they have become essential for a wide range of applications (e.g., aerospace, oil and gas and renewable energy industries). However, due to their limited mechanical, thermal and electrical properties in comparison with typical metallic materials (e.g., steel and aluminum alloys), polymers often need to be modified with different types of fillers to meet the requirements of specific applications. A multitude of filler materials (e.g., nano silver particles, carbon nano tubes, graphene) are available with a wide range of geometries, such as spherical, fiber and platelet shapes. Therefore, developing methods for efficiently characterizing and identifying mechanical and physical properties of filler modified polymers is an important engineering task. The objective of this thesis is to create and validate a numerical modeling framework for predicting mechanical, thermal and electrical properties of particulate polymer composites. In contrast to the high cost and time consuming nature of experiments, this framework is to provide a relatively time- and cost-effective means to guide material design and elucidate experimental observations and analysis results. The first phase of this research project was focused on developing a numerical multiphysics modeling framework to predict the mechanical and thermal properties (i.e., effective modulus of elasticity, Poisson’s ratio, coefficient of thermal expansion, and thermal conductivity), of a single-phase particulate polymer composite with randomly distributed spherical particles. The second phase focus was on expanding the modeling framework to enable property predictions, specifically thermal properties (i.e., effective thermal conductivity), of randomly distributed but aligned cylindrical particulate composites fillers. In the final phase of the research, the numerical framework was extended to predict electrical properties (i.e., effective electrical conductivity, percolation threshold and piezoresistivity), of spherical shape particulate composites. Predicted data were compared against experimental values and analytical models in the different contexts, which indicated overall good agreement between the predictions from the developed modeling framework and experimental works. The developed modeling framework is a valuable contribution facilitating the study of a broad range of material properties, thus improving the material design of filler modified polymers, by comprehensively capturing random aspects of particle and composite morphology.

The integration of phase change materials (PCMs) into building components has attracted in-creasing interest in stabilising indoor temperatures by enhancing the thermal energy storage (TES) capacity and decreasing temperature swings, which lead to an improvement in buildings' thermal comfort and energy efficiency. Gypsum board, with the advantages of low cost and ease of placement, has wide applications for ceiling or wall covering. Thus, PCMs have great potential to be incorporated into gypsum board to improve the energy performance of buildings. However, the application of PCMs has been remarkably restrained by their poor shape stability during the phase change process. Accordingly, a challenge to practical application is that the PCM leak from the building materials. Moreover, due to its low thermal conductivity, the low heat transfer rate of normal PCM also acts as a block upon the wide utilisation of its enormous TES capacity benefits. As yet, very little research has been conducted to study the performance and benefits of using PCMs in real houses, especially in combination with thermal insulation. This study aims to overcome the above issues by containing PCM in porous diatomite material to develop form-stable composite PCM (FSPCM) and study the influence of using FSPCM in max-imising the TES capacity of gypsum board for improving the thermal performance of houses. Test results showed that the produced FSPCM with 48.7 wt.% of diatomite enhanced the thermal conductivity of PCM by 63.7% and eliminated the leakage issue above the PCM melting point. Experimental studies were conducted to develop an energy storage gypsum board by incorporating 40 wt.% of FSPCM in the board. An experimental study and a numerical investigation were conducted to investigate the feasibility of using the FSPCM board as a retrofitting solution to a model house in Sydney, Australia. Furthermore, the effectiveness of the combined use of FSPCM board and thermal insulation in improving the energy efficiency of residential houses was investigated.

In the competitive market of plastic fillers, inexpensive and reliable materials are always sought after. Using a method of thermal conversion, called pyrolysis, a potential contender was created from a plant biomass known as soybean hulls (SBH). The SBH are a byproduct of the soybean farming industry and represent an abundant and inexpensive feedstock. Thermal conversion of the SBH material gives rise to a lightweight carbon-rich filler called pyrolyzed soybean hulls (PSBH). Two separate lots, lot A and lot B, were created with lot A corresponding to SBH pyrolyzed at 450°C (PSBH-A) and lot B corresponding to SBH pyrolyzed at 500°C (PSBH-B). Both lots of PSBH were also milled to reduce their particle size and tested against the as-received PSBH fillers. These milled materials were designated as ground soybean hulls (GSBH).Two different polyolefins, linear low-density polyethylene (LLDPE) and polypropylene (PP), were used for this study. The PSBH fillers were added to the polyolefins in weight percentages of 10, 20, 30, 40, and 50 percent with the resulting plastic/PSBH composites being tested for their mechanical, thermal, and water absorption properties. In general, the addition of filler increased the maximum stress of LLDPE/PSBH composites while reducing maximum stress of PP/PSBH composites. The strain at maximum stress was reduced with increasing amounts of PSBH filler for all composites. Modulus of elasticity generally increased with increasing filler amount. For thermal properties, the addition of PSBH filler increases the heat distortion temperature, increases the thermal decomposition temperature, and reduces the heat of fusion of the composites compared to the neat polyolefins. The liquid absorption and thickness swelling in the materials were small overall but did increase with increasing amounts of PSBH filler and with the time spent submerged in liquid. Milling the PSBH material into GSBH generally had small effects on the various material properties tested and led to easier mixing and a smoother finish on the surface of processed samples. The differences observed between lot A and lot B composites was often small or even negligible.

Abstract: Ternary and quaternary germanides containing rare-earth and transition metals are of interest because of their structural diversity and the potential for interactions between f- and d-electrons. Within the Ce–Rh–Ge system, three new ternary phases Ce3Rh11Ge5, CeRh5Ge3, and CeRh3Ge2 were prepared and their structures were determined by powder and single-crystal X-ray diffraction. Their bonding was examined by calculating electron localization functions and performing a Bader charge analysis, which confirms the description of the structures as consisting of electropositive Ce atoms embedded within an anionic network of Rh and Ge atoms. Within the RE–M–X–Ge (RE = rare-earth metal; M = Mn–Ni; X = Ag, Cd) system, 73 quaternary germanides RE4M2XGe4 adopting the same monoclinic structure (Ho4Ni2InGe4-type) were prepared. A prominent feature in these germanides is the presence of deficient X sites coordinated weakly to Ge atoms in square planar geometry, which may have implications for the low thermal conductivity predicted in these compounds, as confirmed in Nd4Mn2AgGe4. Some representatives of these germanides exhibit additional disorder between the M and X atoms, as seen in Nd4(Mn0.78(1)Ag0.22(1))2Ag0.83(1)Ge4. Solid solutions of these germanides in combination with silicon was investigated in the series Nd4Mn2Cd(Ge1–ySiy)4, in which two intermediate members as well as the end members were characterized structurally.

In this project the effect of polyacrylonitrile (PAN) on thermal and mechanical properties of polyimide (PI) was studied. The aim of this study is to formulate multifunctional polyimide/polyacrylonitrile film by combining excellent properties of polyimide such as high solvent and wear resistance, high dimensional stability, excellent thermal resistance and high modulus with the superior properties of polyacrylonitrile such as low density, thermal stability, high strength and modulus of elasticity. Polyacrylonitrile is a high-performance polymer that unlike others has the capability to form highly oriented molecular structure when subjected to a low temperature heat treatment. It has applications in ultra-filtration membranes, hollow fibers for reverse osmosis and fibers for textile. It is also pre-cursor material for the manufacture of carbon fibers which are characterized by high stiffness, high tensile strength, low weight, high chemical resistance, high temperature tolerance and low thermal expansion. In this study, a polyimide blend containing different weight percentages of polyacrylonitrile (0.1, 0.5, 1, 5 and 10 wt%) was fabricated into thin films and characterized for thermal properties using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Structural and mechanical properties were evaluated using Fourier Transform Infrared Spectroscopy (FTIR) and Dynamic Mechanical Analysis (DMA), respectively. Morphology was studied using an Optical Microscope.From FTIR, the degree of Imidization of the blend was found to be 97.5%. Tg of the copolymer was calculated to be ~370ºC from the tan d peak obtained from DMA. While the 10wt% PAN/PI blend exhibits the highest Tg, the 1% exhibits the highest damping ability. Rate of change of enthalpy was calculated using Differential Scanning Calorimetry which shows that increasing the content of PAN resulted in a decrease in heat release. Percentage mass retained and char retention calculations were done from the TGA data. By utilizing the results obtained from these techniques, this materials suitability for thermo-mechanical applications is discussed in this work.

The overall objective of the study was to investigate different food ingredient conditions and ultrasound treatment on pea protein in terms of surface morphology and thermal characteristics. The motivation of this work was based on previous studies focusing on non-chemical physical modifications of plant proteins and the increasing demand for functional alternative proteins. Ultrasonication time and amplitude, pH, protein concentration, and salt concentration all influenced the thermal and interfacial properties of pea protein. Ultrasound treatment altered the quaternary and tertiary structure of the storage protein and disrupted non-covalent bonds. The structural altercations and a reduction in particle size led to improved functionality. For foams generated at pH 5.0 with 4% (w/v) ultrasound treated protein, the foams had acceptable capacity and stability even when high levels of sugar (5% sucrose) and salt (0.6 M) were incorporated. An acceptable angel food cake simulation can be achieved by replacing egg white with ultrasound treated pea protein. Color and loaf height were different, but similar texture profiles were achieved. Ultrasound treatment significant improved the emulsifying capacity (up to 1.4 fold), emulsion stability, and creaming index compared to control samples (no ultrasound) over two weeks. The ultrasound treated emulsion yielded lower TBARS values, likely due to the change in exposed protein reactive groups. These findings demonstrate that ultrasound processing is an effective nonchemical method to change the structural and physiochemical properties of pea protein. Pea protein processed with this method might allow for the functionality in a bakery, dressings, or beverage products, which is appealing to many consumers and manufacturers.

Municipal solid waste (MSW) in landfills can reach temperatures greater than 50°C that may be sustained for several decades due to methanogenic bacterial activity. The generated heat is an alternative energy source that can be exploited for direct heating of nearby infrastructure or for augmenting industrial processes. However, the proper design of heat extraction systems for landfills requires in-situ measurements of MSW thermal properties and knowledge of the process of heat generation within the waste. Accordingly, the main objective of this study is to understand the processes governing heat generation and heat extraction in MSW and to characterize the thermal properties of the waste. To reach this objective a new MSW landfill cell at the Sycamore Landfill in Santee, California was instrumented with temperature sensors and geothermal heat exchangers, installed at three different elevations in the cell during waste placement. The spatial and temporal evolution of the waste temperature was monitored during 13 months of a self-heating period, followed by a 17-day heat extraction thermal response test, and lastly, a 3-month temperature recovery period. The data collected during the monitoring was analyzed using three different methods of increasing complexity: an infinite line source analysis, a two-dimensional inverse analysis using a finite difference model with simplified heat transfer boundary conditions, and a three-dimensional inverse analysis using a finite element model for heat transfer and nonisothermal pipe flow. The estimated values of in-situ thermal conductivity and thermal diffusivity of the MSW were consistent with values on the higher range of those obtained from laboratory tests on MSW reported in the literature. The data also suggests a dependence of the heat generation rate on the temperature of the surrounding waste, similar to that observed for methanogenic bacterial activity. The experimental and simulation results constitute the basis for the design of geothermal heat exchange systems in MSW landfills. The successful implementation of the heat exchange system in MSW landfill indicates that similar systems can be used for long-term heat extraction, or for maintenance of waste temperatures to enhanced methane generation or waste settlement, or to protect landfill liner or cover systems.

Geopolymeric materials have recently attracted increasing research due to the need to reduce global CO2 emission as well as the growing desire for utilisation of waste and by-products in construction materials. Furthermore, geopolymers are well-known for their excellent behaviour in terms of fire performance which is a matter of great concern in structural design. This thesis presents a study on the development of one part geopolymer concrete (OGC) and hybrid OPC-geopolymer concrete (HGC) mixes and their behaviour at both ambient and elevated temperatures and their application in reinforced concrete columns. The intention for development of one part geopolymer concrete is to improve the commercial viability of geopolymers in building industry. The previous studies mainly emphasized on the investigation of geopolymeric material properties at ambient and elevated temperatures and only a few experimental studies have been devoted to explore the fire performance of reinforced geopolymer concrete members. Thus, this research aims to address this research gaps. In this study, material properties such as slump, density, compressive strength, modulus of elasticity, tensile strength and stress-strain behaviour of OGC and HGC mixes are compared with those of reference Ordinary Portland Cement concrete (CC) mix. Furthermore, the hot compressive strength and thermal properties of the mentioned mixes were measured. Microstructural characterisation was also performed on OGC, HGC and CC samples using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) to provide better insight into microstructure of materials with distinct properties. Two kinds of structural tests were performed on the reinforced geopolymer concrete columns. Two reinforced columns made of OGC and HGC were loaded axially at ambient temperature. The effects of concrete type on the failure modes, development of axial and lateral strains and ultimate load capacity of reinforced columns are examined. In addition, the test results are compared with finite element (FE) analysis for HGC and OGC compared with CC columns. Another ten columns including 3 OGC, 3 HGC and 4 CC columns were tested in fire in which each column was exposed to a given constant load level at ambient temperature, then heated until the column failed. The effects of concrete type (OGC, HGC and CC) and load level (0.3- 0.45 of ultimate) were studied in the test program. The experimental results demonstrated that the use of geopolymer concrete has the potential to enhance the fire resistance of reinforced columns. Furthermore, the achieved data from the experiments such as temperature development, axial and lateral deformation, fire resistance time and failure modes have improved the understanding of the performance of reinforced OGC and HGC columns subjected to fire condition. The test data was also used to verify the proposed finite element (FE) modelling approach in which a finite element model, using ABAQUS commercial software, simulates the behaviour of reinforced OGC, HGC and CC columns. A reasonable agreement was observed by comparing the results obtained from experiments and FE analyses. This research confirms the practicality of employing sustainable one-part geopolymer concrete in structural members and its benefits to improve the thermal insulation or fire performance of reinforced concrete members.

Abstract: With growing concern over global warming and greenhouse gas emissions, research must be undertaken to reduce the environmental footprint of buildings. Cellular concrete provides good strength to weight ratios and good thermal insulation because of its cellular structure. This makes it suitable for reducing the energy demands of buildings constructed with this material. However, the Portland cement currently used in cellular concrete releases large amounts of CO2 during its production. Alternative materials to Portland cement can provide lower carbon footprints. Alkali activated materials can fully replace Portland cement with an alumino-silicate source which is reacted with an alkaline solution. Common alumino-silicate sources are often industrial by-products, so the use of alkali activated materials both reduces the need for Portland cement and diverts by-products from landfills. Renewably sourced ashes also have potential for replacing Portland cement. Ash from the burning of hog fuel in the pulp and paper industry can be used to partially replace the Portland cement in concrete mixes. Applying these more environmentally friendly materials to cellular concrete will produce a material with low carbon emissions for production and high environmental performance for buildings constructed using them. In this thesis, cellular concretes are prepared with cast densities from 100 kg/m3 to 1400 kg/m3 out of alkali activated fly ash, and out of Portland cement blended with up to 20% wood ash. The mechanical, thermal, and acoustic properties of these cellular materials are characterised, and the effects of the differing cementitious materials on these properties are analysed. The cellular structure of the materials is characterised through the use of image analysis, and relationships between the structure and the thermal and acoustic properties of the materials are analyzed.

Abstract: The non-degradable polymers currently used for commercial production and application may be inexpensive; however, their excessive use is leading to unprecedented amounts of plastic waste and extensive environmental damage. The demand for biologically-derived, biodegradable polymers is therefore increasing, as these materials are an environmentally attractive alternative to polymers of petrochemical origin. The biopolymer polyhydroxybutyrate (PHB) is bio-based, biodegradable, and biocompatible, giving it a significant advantage over fossil fuel-based polymers in regards to environmental impact. It has great potential for applications in areas such as food packaging, pharmaceuticals, and biomedical engineering; however, PHB has a narrow thermal processing window and current processing methods are very expensive and lead to poor mechanical properties, such as low flexibility and high brittleness. In this work, PHB materials and methods for thermal processing were investigated, so as to determine whether or not the material can be processed efficiently. The effects of processing PHB through extrusion, hot-pressing, and fused deposition modelling (FDM) – a relatively cheap and efficient additive manufacturing process commonly known as 3D printing – on its morphology, thermal, and mechanical properties were studied. Additionally, the introduction of epoxidized canola oil (eCO) as a green plasticizer, polylactic acid (PLA) as a polymeric plasticizer, and zinc acetate as a possible reaction catalyst to help the blending between PHB and PLA, into the PHB polymer matrix was studied to determine if the processability and flexibility drawbacks could be improved. Pure PHB pellets were melted and extruded into blended samples (containing different amounts of PHB, PLA, eCO, and catalyst) using a twin-screw micro-extruder system. This material was then hot-pressed into 0.5 mm thick polymer sheets and tested. In addition to these samples, another set of experiments was performed where the same PHB pellets were melted and extruded into neat filaments of 1.75 mm diameter. These filaments were fed into a desktop FDM/3D printer equipped with a hotend extruder and print bed at controlled, elevated temperatures to directly deposit (i.e. print) filaments into tensile specimens. Scanning electron microscopy (SEM), stereomicroscopy, confocal microscopy, and Fourier-transform infrared spectroscopy were used to study the morphology and structure of the resulting samples. Differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) measurements were used to study the thermal properties, stability, extent of degradation, and crystallinity of the final products. Tensile testing was also used to assess the mechanical properties of the products. Negligible changes in thermal properties and stability were observed following the extrusion, hot-pressing and FDM processes, and neat PHB samples from the two final processes (i.e. hot-pressing and FDM) have comparable properties to solvent cast thin film samples of PHB (created in another work using acetic acid) while also being in the range of observed mechanical properties for bulk PHB. These results indicate that PHB can be effectively extruded, hot-pressed, and patterned using FDM printing, with little loss in properties. For FDM processing specifically, which is easy to use, cost-efficient, and commercially scalable, significant mechanical property improvements can result with optimization of the printing process. Similarly, the addition of bio-based plasticizing agents eCO and PLA (together or separately) gave no significant changes in thermal properties or stability (as compared to neat PHB samples) at the processing and analysis temperatures chosen. The addition of 10 wt% eCO into neat PHB produced the most promising results, as the oil introduced positive plasticizing effects on the PHB matrix (i.e. increased flexibility with an expected decrease in strength). With the addition of PLA (25 wt%) and the blending catalyst (0.3 wt%), an improvement in flexibility and a decrease in strength parameters were also observed as compared to pure PHB. Finally, eCO may also give promising plasticizing results when added to a PHB/PLA blend (in a 3:1 ratio of PHB:PLA), as the addition of 5 wt% eCO produced equivalent results as compared to the sample without oil. However, the addition of 10 wt% eCO gave a statistically significant decrease in both strength and flexibility, as compared to the PHB/PLA blended sample, providing evidence that an optimum point of plasticizing material had been surpassed. By fine-tuning the amount of eCO and PLA in the PHB matrix, it is possible to create a bio-based polymer product more suitable for commercial use and more beneficial for the environment.

Oats are minor cereal crop and widely used as breakfast cereals. Oat starch is a by-product derived from the β-glucan extraction process and is widely used in food and non-food products such as oat meal, soups, gravies, coating agents for tablets and gloves and cosmetic products. It is also used for oat meal and other novel oat based food products such as oat puddings and oat-based sports gel consisting of oat starch and milk protein ingredients. These products normally undergo thermal treatment, where starch-milk protein interactions could affect the product’s final rheological and sensory properties. Oat starch also exhibits unique properties including small granule size, a well developed granule surface and high lipid content. Hence, the overall aim of this thesis was to determine the effect of milk protein ingredients on oat starch and to advance our understanding of how starches and milk proteins interact with each other. The effect of substituition of oat starch and oat flour at various concentrations (5% and 10%, w/w) with three different readily available milk protein ingredients, namley whey protein concentrate (WPC), whey α-lactalbumin (WLAC) and skim milk powder (SMP) were investigated. All three ingredients decreased the pasting responses of oat starch. SMP showed a greater effect on oat starch characteristics in oat starch and flour systems in comaprison with WPC and WLAC. It was evident that even a small (5%) substituition of oat starch/flour with milk protein ingredients resulted in loss of native properties of oat starch/flour systems, where SMP affected these properties most. SMP increased the pasting temperature and decreased the starch swelling. The effect of the addition of different concentrations (25%, 50%, 75% and 100%) of pure protein fractions, whey protein isolate (WPI) and calcium caseinate (CaCN) on oat starch were also investigated. Studies on the thermal behaviour of oat starch/milk proteins mixtures by differential scanning calorimetry (DSC) showed that WPI and CaCN increased the peak temperature (TP), suggested delaying of starch gelatinisation, where WPI had a greater effect on oat starch than CACN. The X-ray diffraction and Fourier transform infrared spectroscopy studies revealed that oat starch/WPI mixtures increased the relative crytallinity suggesting an increase in ordered structure, while a decrease in IR bands at 1024 cm-1 and 1080 cm-1 indicated less gelatinisation of starch molecules. CaCN did not affect the relative crystallinity and showed an increase in amorphous structuration in FTIR analysis, which is an indication of complete gelatinisation. The qualitative viscoelastic behaviour of oat starch/milk proteins gels were studied in terms of steady state flow behaviour, amplitude strain sweep and thixotropic analyis. WPI and CaCN increased the shear thinning behaviour of oat starch/milk proteins gels, while WPI decreased the elastic modulus (G’) up to 75% concentration and increased at 100%. However, CaCN resulted in an increase in viscous modulus (G”), indicating weak viscous gels in comparison with WPI/ oat starch gels. WPI and CaCN at high concentration (100%) resulted in an increase in elastic nature, but gels were found to be brittle in nature. Finally, it was concluded that WPI illustrated high potency to affect oat starch gelatinisation in comparison with CaCN. This study is a first step to understand the oat starch- milk protein ingredients behaviour during thermal processing, and the trends obtained from the resultant work could predict the usage of oat starch/milk proteins in the development of oat-milk based foods.

The need for improved efficiency of automotive thermal management system is driven by the trend that the automotive powertrain system operates towards higher power output with smaller system size. In other words, the intensified heat dissipation loads from the powertrain system need more efficient cooling solutions. One effort is to enhance the thermal performance of the conventional automotive heat transfer fluid, typically ethylene glycol/water mixture, due to its intrinsically poor thermal property. Nano-fluids have been synonymous with the nanotechnology-based advanced cooling fluids which are derived by homogeneously dispersing nanometer-sized particles into conventional heat transfer fluids. In this study, a multi-parameter approach is used to investigate the behavior of the Aluminum Oxide (Al2O3) nano-particle based nano-fluids. The nano-particles are dispersed in 50/50 vol.% ethylene glycol/distilled water mixture and the other two base fluids (distilled water and ethylene glycol). Two-step method is used for the nano-fluid sample preparation. Nano-fluid sample is characterized by TEM imaging, particle surface charge, particle sizing, light absorbance and pH. Nano-fluid thermal properties are investigated by measuring the thermal conductivity and viscosity at different temperatures. The nano-particle sedimentation within the nano-fluid is determined. The aging effect on the nano-fluid thermal properties is studied. The results offer multiple-perspective correlations between the nano-fluid characterization and performance. xiv Further, the experimental investigation is conducted to evaluate the forced convection heat transfer coefficient of Al2O3 based nano-fluids in the Reynolds number range of 3000 to 4000. The different nano-particle concentrations are tested. The heat transfer test section is basically a concentric double pipe heat exchanger. The inside pipe is designed to simulate a vehicle radiator tube flow condition, where the heated nano-fluid is circulating. The outside pipe is used for circulating the cooling water. The nano-fluid temperature at the inlet of the test section is kept at 60°C ±5°C. The result develops the correlation between nano-fluid convection heat transfer coefficient and Reynolds number as a function of nano-particle concentration.

Abstract: Understanding water flow and heat transport processes in frozen/freezing soils is limited by methodologies for simultaneous, automated measurement of soil properties affecting soil water and heat flux. The major objective of this dissertation was to develop and evaluate time domain reflectometry (TDR) and heat pulse (HP) methodologies to measure soil liquid-water and ice content and soil thermal properties in order to better understand the physics of water flow and heat transport in frozen soils. Extensive lab work was performed and datasets from published work and soil moisture monitoring stations were used to validate and apply these methodologies. The main results are: (1) two multiphase dielectric mixing models that can be parameterized with unfrozen soil and implemented in frozen soils to accurately estimate liquid-water and ice content simultaneously with TDR method alone; (2) application of the developed TDR method to field data facilitates the understanding of soil freeze-thaw processes and snowmelt infiltration under natural boundary conditions despite the assumption of constant soil water content; (3) the dual probe HP method in combination with the TDR method can be used to quantify HP-induced ice melting and correct HP-measured specific heat capacity at high subfreezing temperatures; and (4) the soil freezing-thawing curve (SFTC) measured with these methods can be used explain the hysteresis, freeze-thaw processes, snowmelt infiltration and ice melting resulted from HP method. The application of these methodologies will advance the understanding of mass and energy transport in frozen soils and will spur the development of more innovative methodologies.

Performance-based fire safety system design enables fire safety engineers to assess the performance of buildings and components by taking into account various scenarios of real fires and their severity. This approach offers more flexibility to the fire safety engineer to adopt new design concepts such as aesthetic values, material and energy efficiencies, while complying with regulatory building codes. For such an approach, the testing of fire safety systems either experimentally or numerically is essential and since experimental studies are vastly expensive, fire models are usually used. State-of-the-art Computational Fluid Dynamics (CFD) based fire models typically include pyrolysis and combustion sub-models for predicting fire growth and spread in addition to background mass, momentum and energy balance sub-models. Separately, the phenomena of pyrolysis and combustion of materials are quite complex and during a fire both phenomena occur simultaneously thus compounding the complexity. Simulating these phenomena relies primarily on the prescribed fire properties of combustible materials and any error in providing the input fire properties data may affect the prediction of the fire behaviour. This study has been conducted to characterize the fire properties for coupled pyrolysis and combustion simulation. The overarching objective is to find, given an unknown or novel material, how would a user go about quantifying the representative fire properties and use them optimally? A range of experimental techniques and where necessary, data post-processing methods have been established, developed, selected and implemented to determine critical fire properties. Two bench-scale instruments, the cone calorimeter and hot disk analyser, as well as two miligram-scale instruments, a thermogravimetric analyser and differential scanning calorimeter, have been used for this purpose.

Junctions are the key component for 3D carbon nanotube (CNT)-graphene seamless hybrid nanostructures. Growth mechanism of junctions of vertical CNTs growing from graphene in the presence of iron catalysts was simulated via quantum mechanical molecular dynamics (QM/MD) methods. CNTs growth from graphene with iron catalysts is based on a ‘‘base-growth’’ mechanism, and the junctions were the mixture of C-C and Fe-C covalent bonds. Pure C-C bonded junctions could be obtained by moving the catalyst during CNT growth or etching and annealing after growth. The growth process of 3D CNT-graphene junctions on copper templates with nanoholes was simulated with molecular dynamic (MD) simulation. There are two mechanisms of junction formation: (i) CNT growth over the holes that are smaller than 3 nm, and (ii) CNT growth inside the holes that are larger than 3 nm. The growth process of multi-layer filleted CNT-graphene junctions on the Al2O3 template was also simulated with MD simulation. A simple analytical model is developed to explain that the fillet takes the particular angle (135°). MD calculations show that 135° filleted junction has the largest fracture strength and thermal conductivity at room temperature compared to junctions with 90°,120°, 150°, and 180° fillets. The tensile strengths of the as-grown C–C junctions, as well as the junctions embedded with metal nanoparticles (catalysts), were determined by a QM/MD method. Metal catalysts remaining in the junctions significantly reduce the fracture strength and fracture energy. Moreover, the thermal conductivities of the junctions were also calculated by MD method. Metal catalysts remaining in the junctions considerably lower the thermal conductivity of the 3D junctions.

Current commercially available prosthetic liners and sockets insulate the residual limb, causing the temperature of the residual limb to increase. As a result, the residual limb sweats excessively, leading to numerous dermatologic conditions. These skin problems can impart physical and psychological burdens on the amputee patient and hinder their rehabilitation process. Overall, this study aimed to aid in the rehabilitation of amputee patients by specifically addressing the cause of the increased residual limb temperatures. This was accomplished in three aims. The first aim focused on quantifying the thermal barrier posed by materials currently used in prosthetic liners and sockets by measuring the materials’ thermal conductivities. All materials were shown to be significant insulators. The second aim approached the problem of increased temperatures by modifying a prosthetic socket, then using computer simulations to observe the temperature difference between the inner and outer socket walls. Three sockets were modeled: two modified sockets, each containing a cooling channel 0.5 cm in diameter; and a control socket. A greater temperature drop across the socket wall suggested that the socket could provide cooling benefits to the residual limb by allowing for heat to be drawn away from the limb, towards the cooling channels. Socket type and location on the socket were statistically significant factors affecting the predicted temperature difference. This finding suggests that modifications of a prosthetic socket could offer a cooling effect to amputee patients. Aim 3 focused on validating that computer simulation from Aim 2. 3D printed prototype sockets were constructed. The socket with the greatest observed average temperature differential was the socket with an eight revolution cooling channel in its wall. This finding suggests that socket modifications, like the cooling channel presented, could provide a cooling effect to the residual limb. Overall, this study showed that future iterations of prosthetic liners and sockets should take the thermal properties of the designs into account to provide the greatest benefit to amputee patients.

Objective molecular dynamics (OMD) is a recently developed generalization of the traditionally employed periodic boundary conditions (PBC) used in atomistic simulations. OMD allows for helical and/or rotational symmetries to be exploited in addition to translational symmetry. These symmetries are especially prevalent in nanostructures, and OMD enables or facilitates many simulations that were previously dicult or impossible to carry out. This includes simulations of pristine structures that inherently possess helical and/or angular symmetries (such as nanotubes), structures that contain defects (such as screw disclocations) or stuctures that are subjected to deformations (such as bending or torsion). OMD is already a powerful method, having been coupled with the quantum-mechanical density functional-based tight-binding (DFTB) method, as well as with classical potentials. In this work, these capabilities are used to investigate electromechanical properties of silicon nanowires, treating the mechanical simulation results in the context of continuum mechanics. The bending of graphene is studied, and the underlying molecular orbital mechanisms are investigated. The implications of the results on other simulation methods used to study bending of graphene are discussed. OMD is used in an experimental-theoretical collaboration studying the kinking of graphene and boron nitride nanoribbons. The simulations elucidate and quantify the underlying mechanism behind the kinking seen in experiments.Although theoretically, as a generalization, OMD can match or exceed the capabilities of PBC in all cases, OMD is a new method. Thus, practical implementation must be tackled to expand the capabilities of OMD to new simulation methods and simulation types. In this work, OMD is expanded to allow coupling with self-consistent charge (SCC) DFTB, by developing and implementing the required summation formulas for electrostatic and dispersion interactions. SCC-DFTB is an improved form of the standard DFTB method which includes explicit consideration of charge transfer between atoms. This allows for improved description of heteronuclear materials. To demonstrate this capability, proof-of-concept calculations are carried out on a boron nitride nanotube, a screw-dislocated zinc oxide nanowire, and a single-helix DNA molecule.Finally, preliminary development of heat current calculations under OMD is presented. Heat current calculations are used for calculating thermal conductivity of materials from equilibrium molecular dynamics. So far, heat current calculations have been implemented for the pairwise Lennard-Jones potential. The next development (not yet implemented) is the extension of the heat current calculation under OMD to the Tersoff interatomic potential. The challenges and considerations involved are discussed.

A recent trend in the development of renewable and biodegradable materials has led to the development of composites from renewal sources such as natural fibers. This agricultural activity generates a large amount of waste in the form of peanut shells. The motivation for this research is based on the utilization of peanut shells as a viable source for the manufacture of biocomposites. High-density polyethylene (HDPE) is a plastic largely used in the industry due to its durability, high strength to density ratio, and thermal stability. This research focuses in the mechanical and thermal properties of HDPE/peanut shell composites of different qualities and compositions. The samples obtained were subjected to dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and mechanical tensile strength tests. TO prepare the samples for analysis, the peanut shells were separated into different mesh sizes and then mixed with HDPE at different concentrations. The results showed that samples with fiber size number 10 exhibited superior strength modulus of 1.65 GPa versus results for HDPE alone at 1.32 GPa. The analysis from the previous experiments helped to determine that the fiber size number 10 at 5%wt. ratio in HDPE provides the most optimal mechanical and thermal results. From tensile tests the highest modulus of elasticity of 1.33 GPa was achieved from the samples of peanut shells size number 10 in HDPE at 20%wt. ratio, while the results for HDPE alone were only of 0.8 GPa. The results proved the hypothesis that the addition of peanut shells to HDPE enhances both the thermal and mechanical properties of the composite.

The Purpose of this thesis is to experimentally demonstrate an inversion analysis technique, developed by Dr. Jay Frankel (UTK), that utilizes transient temperature data from probes embedded at known locations in a material. This allows one to determine thermal properties (thermal diffusivity and thermal conductivity) of the material, surface temperature, and the surface heat flux as they change with time. Dr. Frankel’s inversion method can be used to determine surface temperature and heat flux of a one-dimensional semi-infinite slab based on the transient data from one or two embedded probes, if the thermal conductivity and thermal diffusivity of the material are known. Frankel’s theory suggests that the thermal properties of the material can be determined if transient data from two thermocouple (TC) probes at known locations and the heat flux at the surface are known. This thesis investigates finding the thermal properties and surface temperature of materials using a two embedded thermocouple approach. As an initial check to the inversion analysis, the theoretical temperature solution for a one-dimensional semi-infinite slab was used. This validated that the analysis could converge to the constant thermal properties for the theoretical material. An experiment was run again to provide data for the materials copper and aluminum. Using a real material is fundamentally different from using theoretical determined (analytical) data, because the thermal properties for a real material vary with temperature. Since the inversion analysis converged to a constant solution for the theoretical temperatures, it was believed that the real material will converge to a solution. However, it was seen that the thermal diffusivity for the real materials never converged to the expected value. Although, when a constant handbook value for the thermal diffusivity is used to calculate the thermal conductivities from the experimental temperature data collected from the internal probes, the inversion analysis resulted in good agreement with experiment.

The outstanding properties of carbon nanotubes (CNTs) have stimulated a large number of researches to explore the potential of using them as reinforcement in polymer composites. Although many studies have reported the enlighten improvement of the materials properties by using CNTs as reinforcement, there are no promising and optimal results have been concluded to date. This thesis aims at studying the mechanical properties on thermoset polymer, Epoxy, by employing a small amount of carbon nanotubes as reinforcement. Two different types of nanotube-based composites are prepared i.e. a raw single-walled carbon nanotube (SWNT) composites and a functionalized single-walled carbon nanotube (FSWNT) composite. Chemical functionalization on SWNTs with carboxyl functional group (COOH) aims at modifying the end caps of nanotubes, so to provide covalent bonding of SWNTs to the polymer matrix during manufacturing of composite systems. Different weight percentages (wt %) of each type of SWNTs are added into the composite system. Standard test methods are performed on these nanotube composite systems and satisfactory results were achieved when the weight percentages of both types of SWNTs increased. Through the comparison between two systems (raw SWNTs and FSWNTs), the FSWNT reinforced composite is found to provide a better improvement on the mechanical properties as compared with the SWNT reinforced system. The integrity of both composite systems is examined by using Scanning Electronic Microscopy (SEM). The SEM images of the composites indicated the derivation in wetting and bonding between the nanotubes (both SWNTs and FSWNTs) and epoxy resin, and the FSWNTs provide an eminent dispersion when compared with the SWNTs in the composite system. Moreover, thermal testings are employed to further investigate the interfacial interaction between the nanotubes and the polymer matrix. xiv Molecular Dynamics (MD) simulations are also carried out to investigate the structural change of a SWNT under different temperature-controlled manufacturing environments. Swivel of the SWNT was noticed as the temperature increased. Such alteration in structure form can provide physical interlocking between SWNT and its surrounding polymer system. Thus, its overall mechanical and thermal properties can be enhanced.

Seal glass is essential and plays a crucial role in solid oxide fuel/electrolyzer cell performance and durability. A seal glass should have a combination of thermal, chemical, mechanical, and electrical properties in order to seal different cell components and stacks and prevent gas leakage. All the desired properties can simultaneously be obtained in a seal glass by suitable compositional design. In this dissertation, SrO-La₂O₃-A₂O₃-B₂O₃3-SiO₂ based seal glasses have been developed and composition-structure-property relationships have been investigated. B₂O₃ free SrO-La₂O₃-Al₂O₃-SiO₂ based seal glass is the most suitable and its compatibility with the metallic interconnects and sealing performances have been evaluated. A seal glass should be stable for 5,000-40,000 hrs in the oxidizing and reducing atmospheres at 600-900°C but both the thermal and chemical stability is a persistent problem. The effect of Al₂O₃ on a SrO-La₂O₃-Al₂O₃-B₂O₃-SiO₂ based seal glass has been studied to improve the thermal properties, such as glass transition temperature, softening temperature and thermal expansion coefficient, and the thermal stability. Al₂O₃ improves the thermal stability but does not significantly affect the thermal properties of the seal glass. Comprehensive understanding of composition-structure-property relationships is needed to design a suitable seal glass. The thermal properties and stability of a borosilicate seal glass depend on the B2O3:SiO2 ratio in the composition. The role of B₂O₃:SiO₂ ratio on the glass network structure of the SrO-La₂O₃-Al₂O₃-B₂O₃-SiO₂ based seal glasses has been studied using Raman spectroscopy and nuclear magneto resonance spectroscopy. The thermal properties and thermal stability were correlated with the glass network structure and the calculated network connectivity. This study shows that the thermal properties degrade with increasing B₂O₃:SiO₂ ratio due to increase in the non-bridging oxygen and decrease in the network connectivity. High B₂O₃:SiO₂ ratio induces BO4 and SiO4 structural unit ordering, increases micro-heterogeneity, and subsequently degrades thermal stability. B₂O₃ free SrO-La₂O₃-Al₂O₃-SiO₂ seal glass shows the best combination of the thermal properties and thermal stability among the studied glasses. Nickel or nickel oxide is added into a seal glass to modify the thermal properties depending on the specific composition. The role of nickel as a network former or modifier and its effect on the thermal properties and thermal stability of the SrO-La₂O₃-Al₂O₃-SiO₂ based seal glasses have been investigated. Nickel is a modifier in this glass system and does not improve the thermal properties but degrades thermal stability by decreasing network connectivity and inducing micro-heterogeneity. The interconnect-seal glass interface stability is the most crucial for solid oxide fuel/electrolyzer cell. Crofer 22 APU and AISI 441 alloys are the preferred interconnects. The interfacial stability of the SrO-La₂O₃-Al₂O₃-SiO₂ based seal glass with these alloys have been studied as a function of time (0-1000 hrs), temperature (700-850°C), atmospheres (air, argon, and H₂O/H₂) using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction analysis (XRD). Complementary analytical techniques such as wave length dispersive spectroscopy (WDS) and SEM of thin samples were also carried out for selected samples. This study shows good interfacial stability of the SrO-La₂O₃-Al₂O₃-SiO₂ based seal glass with these alloys for the studied conditions. A suitable seal glass should be hermetic and withstand 100-1000 thermal cycles for practical application. Sealing performances of the SrO-La2O3-Al2O3-SiO2 based seal glass have been evaluated by pressure-leakage method. The seal glass is hermetic for at least 2000 hrs and withstands 100 thermal cycles. Overall, present work shows that the SrO-La₂O₃-Al₂O₃-SiO₂ based glass has all the desired properties and suitable for solid oxide fuel/electrolyzer cell seal.

High pressure processing (HPP; 100-700 MPa at temperatures < 45°C) and pressure-assisted thermal processing (PATP) (500-700 MPa; 90-120°C) have been used to inactivate pathogenic and spoilage bacteria and produce high quality foods. The objectives of this dissertation were to evaluate the influence of various pressure-temperature combinations on quality, microbial lethality and thermophysical properties of selected foods. Experiments were conducted to investigate the influence of process temperature (95-121°C) at different pressures (0.1, 500-700 MPa) on carrot quality. Results indicated that under comparable process temperatures (up to 105°C), pressure-assisted thermal processing (PATP) retained the carrot quality attributes such as color and carotene content better than thermal processing (TP). However, process and preprocess thermal history greatly influenced carrot textural change. Pressure protective effects on product hardness at elevated temperatures (110-121°C) were less pronounced. Subsequently, experiments were conducted to evaluate the role of pressure during sequential (pressure pre-treatment at ambient temperature followed by TP) or simultaneous (PATP) treatment in preserving product quality attributes. To learn how different food matrices are influenced by various pressure-heat combinations, experiments were also carried out using carrot, jicama, red radish, zucchini, and apricot. Results showed that TP degraded product texture severely but HPP followed by TP improved texture retention. In comparison to TP alone, PATP better retained texture and color. The beneficial effects of PATP may come from the densification of the tissue due to pressurization or biochemical changes of the pectic substances. Texture retention was product dependent, with jicama being the least influenced among the foods tested. An instrumental based crunchiness index (CI) was developed and validated using sensory data. CI was able to describe textural transformation of various processed products. In-situ thermal conductivity (k), diffusivity (α), volumetric specific heat (ρCp) and isobaric specific heat (Cp) of tomato puree, soy protein isolate (10% W:V), soybean oil, guacamole, honey, cream cheese and sucrose solution (10% W:V) were measured up to 600 MPa at 25°C by a dual needle probe adapted to elevated pressures. Increasing pressure linearly increased k values. Among the food materials tested, the maximum increase in k under pressure was observed for soybean oil (0.173 -0.256 W/m°C), while k of honey had the least change (0.324 – 0.396 W/m°C). Thermal diffusivity of the tested materials showed a positive pressure dependence and can be expressed as a second order polynomial function of pressure. Isobaric specific heat of food materials decreased with increase in pressure. The maximum combined uncertainty in the measurement of k, α, ρCp and Cp were 3.1, 6.8, 6.6 and 6.9%, respectively.A model was developed to calculate accumulated lethality during PATP. A differential equation that considered momentary inactivation rates as a function of pressure and temperature was formulated and numerically solved using Rung-Kutta method. The model was experimentally validated under different process conditions. Predicted log-reduction computed by the model using nth order kinetics was found to be in good agreement with experimental values. The ability of the model to predict microbial reduction was found to be satisfactory when evaluated under various process scenarios.

The effect of incorporation two clays; layered double hydroxides (LDH) and montmorillonite layered silicates (MLS) in linear low density polyethylene (PE) matrix was investigated. MLS and LDH were added of 5, 15, 30 and 60 weight percent in the PE and compounded using a Brabender. Ground pellets were subsequently compression molded. Dispersion of the clays was analyzed using optical microscopy, SEM and XRD. Both the layered clays were immiscible with the PE matrix and agglomerates formed with increased clay concentration. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Both clays served as nucleation enhancers increasing recrystallization temperatures in the composites. Flame retarding properties were determined by using the flammability HVUL-94 system. LDH indicated better flame retarding properties than MLS for PE. The char structure was analyzed by environmental scanning electron microscopy. Mechanical properties were studied by tensile testing and Vickers microhardness testing apparatus.

Estimating the thermal properties of thin film on substrate material systems is important in many thermal engineering applications. The photothermal deflection spectroscopy technique is extended for the in situ characterization of anisotropic thin films on substrates. A comprehensive thermal model is developed for systems with an arbitrary number of films on a substrate that includes the effects of anisotropic thermal conductivity and thermal boundary resistance. Using the thermal model, the beam deflections in a photothermal deflection spectroscopy experiment are found for a system with finite probe beams. The theoretical beam deflection model is used to infer material properties within a Bayesian statistical framework. A maximum a posteriori estimator based on the Levenberg-Marquardt algorithm is used to solve the resulting ill-posed inverse problem. Synthetic data from bulk, thin film on substrate, and multilayered film samples is analyzed to demonstrate the ability and limitations of the estimator to infer the true thermal properties. The estimation of effective thermal properties for multilayer material systems is also discussed and demonstrated. Methods for evaluating the validity of estimates and subsequently improving these estimates using design of experiments are given.

Sensors and actuators featuring biomimetic properties, with linear and angular resolution, good compliance and long term biostability are in growing demand for applications such as synthetic muscles, sensor equipped limps and other bio-engineering designs. Recent research papers have demonstrated that insulator materials coated with polypyrrole or polyaniline and combined with various dopants can achieve piezoresistive and dielectric properties, enabling the detection and displacement of local strains in polymer sheets, textile fibers and fabrics. It is known that composite films made from layers of carbon black (CB) filled polyvinylindene fluoride (PVDF) and high density polyethylene (HDPE) films provide stable piezoelectric behavior in the temperature range from 20 to 140 oC and low tensile loss on exposure to moisture and hydrolytic conditions. However, to date the literature contains no references to the use of this particular polymer system in fiber or textile form. Moreover, since the resistivity of such composites can be quantitatively specified by selectively localizing CB in one polymer phase or at the interface of an immiscible polymer blend, it was hypothesized that bicomponent fiber spinning might lead to similar piezoelectric properties within individual fibers. This research study was therefore aimed first at determining whether a blend of PVDF and HDPE polymers filled with CB could be melt spun and drawn into a series of composite or bicomponent fibers using a laboratory extruder and drawing machine. This was accomplished successfully with loadings of CB varying from zero to 27.7% by weight. The second goal was to determine the weight fraction of CB that should be added to PVDF / HDPE composite fibers in order to optimize their electrical functionality and piezoelectric performance. Analysis of the deformation of the as-spun and drawn fibers in their longitudinal direction during charging and discharging was conducted in a novel piezoresponse force microscope (PFM). It demonstrated that increasing the CB content also increased the ferroelectric hysteresis and piezoelectric constant of the composite fiber up to the percolation threshold of 20.7% of CB by weight. The CB was selectively located in the HDPE phase, resulting in a significant loss of crystallinity in the HDPE phase. At the same time, the PVDF phase was transformed from a non-polar to a polar form. The optimum spun and drawn composite piezoelectric fiber measuring 120 microns in diameter contained 56/32/12 PVDF/HDPE/CB by weight. Under the electric stimulation of a few volts it was predicted to be capable of producing a tensile force of about 2 x 10⁻² N for a 350 mm long fiber with 1 mm 2 cross-sectional area. It is anticipated that a bundle of such piezoelectric fibers measuring 26 mm² in cross-section could generate the force of 0.5 N required to complete flexion of a human distal interphalangeal (finger) joint. The incorporation of CB filled HDPE produces a conductive matrix phase within these bicomponent fibers, which acts as an electrode around the PVDF regions, facilitating a more uniform distribution of the piezoelectric charge within the PVDF phase. These encouraging results bode well for future piezoelectric fibers, which have both rapid electromechanical response and good biostability. Additional larger scale tests are recommended to evaluate the efficiency of these novel biomaterials for use in biomedical and electrotextile end-uses.

A thermo-elastic-plastic model for unsaturated soils has been presented based on the effective stress principle considering the thermo-mechanical and suction coupling effects. The thermo-elastic-plastic constitutive equations for stress-strain relations of the solid skeleton and changes in fluid content and entropy for unsaturated soils have been established. A plasticity model is derived from energy considerations. The model derived covers both associative and non-associative flow behaviours and the modified Cam-Clay is considered as a special case. All model coefficients are identified in terms of measurable parameters. To verify the proposed model, an experimental program has been developed. A series of controlled laboratory tests were carried out on a compacted silt sample using a triaxial equipment modified for testing unsaturated soils at elevated temperatures. Imageprocessing technique was used for measuring the volume change of the samples subjected to mechanical, thermal and hydric loading. It is shown that the effective critical state parameters M, κ and λ are independent of temperature and matric suction. Nevertheless, the shape of loading collapse (LC) curve was affected by temperature and suction. Furthermore, the temperature change affected the soil water characteristic curve and an increase in temperature caused a decrease in the air entry suction. The simulations from the proposed model are compared with the experimental results. The model calibration was performed to extract the model parameters from the experimental results. Good agreement between the results predicted using the proposed model and the experimental results was obtained in all cases.

The objective of this study was to evaluate and gain a better understanding of the short-term impact performance and the long-term durability of electrically conductive adhesives for electronic interconnection applications. Three model conductive adhesives, designated as ECA1, ECA2 and ECA3, supplied by Emerson & Cuming, were investigated, in conjunction with printed circuit board (PCB) substrates with metallizations of Au/Ni/Cu and Cu, manufactured by Triad Circuit Inc. Effects of environmental aging on the durability of conductive adhesives and their joints were evaluated. All the samples for both mechanical tests and thermal tests were aged at 85%, 100%RH for periods of up to 50 days. Studies of bulk conductive adhesives suggested that both plasticization, which is reversible and further crosslinking and thermal degradation, which are irreversible, might have occurred upon exposure of ECAs to the hot/wet environment. The durability of electrically conductive adhesive joints was then investigated utilizing the double cantilever beam (DCB) test. It was observed that the conductive adhesive joint was significantly weakened following hydrothermal aging, and there was a transition from cohesive failure to interfacial failure as aging continued. A comparative study of the durability of different conductive adhesive and substrate metallization combinations suggested that the resistance of the adhesive joints to moisture attack is related to the adhesive properties, as well as the substrate metallizations. It was noted that the gold/adhesive interface had better resistance to moisture attack than the copper/adhesive interface. A reasonable explanation of this phenomenon was given based upon the concept of surface free energy and interfacial free energy. XPS analysis was performed on the fractured surfaces of DCB samples. For adhesive joints with copper metallization, copper oxide was detected on the failed surfaces upon exposure of the conductive adhesive joints following aging. XPS analysis on the fractured surfaces of adhesive joints with Au metallization suggested that diffusion of Cu to the Au surface might have happened on the Au/Ni/Cu plated PCB substrates during aging. The impact performance of conductive adhesives was quantitatively determined using a falling wedge test. This unique impact resistance testing method could serve as a useful tool to screen conductive adhesives at the materials level for bonding purpose. Moreover, this test could also provide some useful information for conductive adhesive development. This study revealed that the viscoelastic energy, which is a result of the internal friction created by chain motions within the adhesive material, played an important role in the impact fracture behavior of the conductive adhesives. This study also demonstrated that the loss factor, evaluated at the impact environment conditions, is a good indicator of a conductive adhesive's ability to withstand impact loading.

The goals of this research are to synthesize novel two and four-component pendent polyimides by attaching the zirconium complex to the respective polymer backbones, and then to compare their characteristics, e.g. thermal properties, atomic oxygen resistance, and film properties, with those of previous students of Dr. Illingsworth, Derek Chow and Wei Wang. Our work focuses on increasing the atomic oxygen resistance of polyimides by increasing their pendent group concentrations. This result can best be achieved by increasing the flexibility of the polymer backbone, which also lowers glass transition temperature (Tg), improves polyamic acid solubility, and, thus, improves processibility. The novel four component "parent" polyamic acid (PAA) based on 1,3-aminophenoxybenzene (APB), 3,4'-oxydianiline (3,4'-ODA), 4,4'-oxydiphthalic anhydride (ODPA), and mellitic acid dianhydride (MADA) was synthesized in freshly dried solvent l-methyl-2-pyrrolidone (NMP), and the Zr(adsp)(dsp) pendent groups attached in the presence of dicyclohexylcarbodiimide (DCC). Portions of each solution, i.e. parent and pendent PAA, were treated with nonsolvent or cast into films. After precipitation, the parent polyamic acid and Zr(adsp)(dsp) pendent polyamic acid powders were thermally imidized using three different processing conditions: 1) 100C, 200C, and 300C for one hour each, 2) 100C for an hour followed by 380C for five minutes, or, 3) 100C for an hour followed by 380C for thirty minutes. The resulting parent and Zr(adsp)(dsp) pendent polyamic acid films were imidized using the same three processes as above. Some of the films of Zr(adsp)(dsp) pendent polyimide were exposed to atomic oxygen in a plasma asher. The synthesized parent and Zr(adsp)(dsp) pendent polyamic acids and polyimides were characterized by thin layer chromatography (TLC), fourier transform infrared (FT-IR), proton nuclear magnetic resonance ('H NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), intrinsic viscosity (IV) determination, laser light scattering (LS), refractive index, solvent resistance testing, optical microscopy, and scanning electronic microscopy (SEM), before and after atomic oxygen exposure for the latter two. TLC results indicate that no free zirconium complexes remain in the Zr(adsp)(dsp) pendent polyamic acid solution. Spectroscopic results support the conclusion that the structures obtained are consistent with the proposed ones. Polyimides were prepared using three different processing conditions. Tgs were higher for the 380C processed material. Decomposition temperatures of pendent polyimides and parent polyimide are all very high, which means that they possess very high thermal stability. Both the intrinsic viscosity results and LS results indicate that a moderate degree of polymerization occurred, and the weight average molecular weight of the pendent polymers is 48,829g/mol. All of the films passed the solvent resistance test in acetone, methyl ethyl ketone, toluene, chloroform, tetrahydrofuran (THF) and THF/methanol mixture for 30 minutes followed by a fingernail crease. The pictures taken by optical microscopy and SEM and visual observation indicate that the atomic oxygen erosion of the zirconium pendent polyimide films leaves a white chalky coating on the surface, which is due primarily to the formation of zirconium dioxide and which retards the further oxidization of polyimide. The eroded Zr(adsp)(dsp) pendent polyimide surface is similar to that observed for analogous three component Zr pendent polymers prepared by D. Chow and W. Wang. For single layer films, the resistance time of Zr(adsp)(dsp) pendent polyimide is more than four times longer than that of the parent polyimide. The maximum tetra(acetylacetonato)zirconium(IV), Zr(acac)4, concentration in the four component parent polymer was determined. Film cracking upon imidization and transparency of films were the criteria used to make this determination. No transparent imidized films can be obtained if the concentration of Zr(acac)4 is 30% by mole or above.

Thermophysical characterization of anisotropic composite materials is extremely important in the control of today fabrication processes and in the prediction of structure failure due to thermal stresses. Accuracy in the estimation of the thermal properties can be improved if the experiments are designed carefully. However, on one hand, the typically used parametric study for the design optimization is tedious and time intensive. On the other hand, commonly used gradient-based estimation methods show instabilities resulting in nonconvergence when used with models that contain correlated or nearly correlated parameters. The objectives of this research were to develop systematic and reliable methodologies for both Experimental Design Optimization (EDO) used for the determination of thermal properties, and Simultaneous Parameter Estimation (SPE). Because of their advantageous features, Genetic Algorithms (GAs) were investigated for use as a strategy for both EDO and SPE. The EDO and SPE approaches used involved the maximization of an optimality criterion associated with the sensitivity matrix of the unknown parameters, and the minimization of the ordinary least squares error, respectively. Two versions of a general-purpose genetic-based program were developed: one is designed for the analysis of any EDO / SPE problems for which a mathematical model can be provided, while the other incorporates a control-volume finite difference scheme allowing for the practical analysis of complex problems. The former version was used to illustrate the genetic performance on the optimization of a difficult mathematical test function. Two test cases previously solved in the literature were first analyzed to demonstrate and assess the GA-based {EDO/SPE} methodology. These problems included the optimization of one and two dimensional designs for the estimation at ambient temperature of two and three thermal properties, respectively (effective thermal conductivity parallel and perpendicular to the fibers plane and effective volumetric heat capacity), of anisotropic carbon/epoxy composite materials. The two dimensional case was further investigated to evaluate the effects of the optimality criterion used for the experimental design on the accuracy of the estimated properties. The general-purpose GA-based program was then successively applied to three advanced studies involving the thermal characterization of carbon/epoxy anisotropic composites. These studies included the SPE of successively three, seven and nine thermophysical parameters, with for the latter case, a two dimensional EDO with seven experimental key parameters. In two of the three studies, the parameters were defined to represent the dependence of the thermal properties with temperature. Finally, the kinetic characterization of the curing of three thermosetting materials (an epoxy, a polyester and a rubber compound) was accomplished resulting in the SPE of six kinetic parameters. Overall, the GA method was found to perform extremely well despite the high degree of correlation and low sensitivity of many parameters in all cases studied. This work therefore validates the use of GAs for the thermophysical characterization of anisotropic composite materials. The significance in using such algorithms is not only the solution to ill-conditioned problems but also, a drastically cost savings in both experimental and time expenses as they allow for the EDO and SPE of several parameters at once.

To determine the feasibility of using low thermal expansion ceramics and aluminum titanate in diesel engine applications, the mechanical and thermal properties and corrosion resistance were evaluated. NZP (Ba1.25Zr₄P5.5Si.0.50₂₄ and Ca0.5 SrO.5Zr₄P₆0₂₄) and aluminum titanate (AT) were exposed to a simulated diesel engine environment. The effects of thermal cycling from room temperature to 700°C, and a combination of alkali corrosion and thermal cycling on the mechanical and thermal properties of these ceramics were examined. It was found that NZP and AT materials demonstrated near zero bulk thermal expansion, good thermal up shock resistance and resistance to Na and V corrosion, because of their porous structure and low density. However, the AT materials exhibited lower flexural strength. This is a direct result of the inherent micro cracking across the AT grains upon cooling from the sintering temperature, which reduces the flexural strength and elastic modulus.

In previous studies, evidence of thermal wave behavior was found in heterogeneous materials. Thus, the overall goal of this study was to experimentally verify those results, and develop a parameter estimation scheme to estimate the thermal properties of various heterogeneous materials. Two types of experiments (Experiments 1 and 2) were conducted to verify the existence or non-existence of thermal wave behavior in heterogeneous materials. In Experiment 1 sand, ion exchanger, and sodium bicarbonate were used as test materials, while processed meat (bologna) was used in Experiment 2. The measured temperature profiles of the samples were compared with the parabolic and hyperbolic heat conduction model results. The values of thermal diffusivity and thermal conductivity were obtained using the Box-Kanemasu parameter estimation method which is based on the comparison between temperature measurements and the solutions of the theoretical model. Overall, no clear experimental evidence was found to justify the use of hyperbolic heat conduction models rather than parabolic for the materials tested. Further comprehensive experimentation using different heating rates is warranted to definitely identify the accurate type of heat conduction process associated with such materials, and to describe the physical mechanisms which produce wave-like heat conduction in heterogeneous materials.

Thermal properties of ten different seafood were measured in this research. They included bluefish (Pomatomus saltatrix), croaker (Micropogonias undulatus), spanish mackerel (Scomberomorus maculatus), pink salmon (Oncorhynhus gorbuscha), black seabass (Atractoscion nobilis), spot (Leiostomus xanthurus), shrimp(Pandalus borealis), tilapia (Tilapia aurea), grey sea trout(Cynoscion regalis), and yellow fin tuna (Thunnus albacares) (Wheaton, et al. 1985). Thermal properties measured were thermal conductivity, thermal diffusivity, and specific heat from 5 to 30oC. Enthalpy was measured from -40 to 30oC. Moisture and fat content were measured. Thermal conductivity and thermal diffusivity were measured by a rapid transient technique using a bead thermistor probe. Specific heat and enthalpy were measured using a differential scanning calorimeter. Moisture content and fat content were measured by the AOAC specified oven dry method and ether extraction method, respectively. The measured thermal properties agreed well with the scarcely available literature values. They were then statistically correlated with moisture and fat content. Based on statistical analysis, mathematical models relating thermal properties and composition were proposed and compared with the models available in the literature. Models for thermal conductivity and specific heat were recommended to predict these properties of meats and fish with similar composition.