<p>In this thesis, factors important in tableting operations and for tablet properties have been studied and characterised by different spectroscopic techniques as well as by some more conventionally used particle characterisation techniques. The spectroscopic techniques solid-state NMR, FT-IR and NIR spectroscopy, proved to be valuable tools in the estimation of particle and tablet properties, offering both specificity and sensitivity in the measurements. Because of the large amount of information obtained in a spectrum, multivariate data analysis was in some cases used in the processing of the spectral data. Correlations between the solid state structure measured by spectroscopy and the particle and tablet properties could be obtained including useful prediction models.</p><p>The surface area obtained using different principles has in this thesis been shown to reflect different properties and tableting behaviour of a collection of pharmaceutical materials. The particle shape and the external surface area of the powders measured by permeametry, were found to be important factors for the tensile strength of tablets made of hydroxypropyl methylcellulose. Furthermore, the external surface area could be used to access dominating interparticulate bonding mechanisms in compacts of different materials by normalising the tablet tensile strength for the tablet surface area. It was also shown that for materials prone to develop solid bridges, the actual surface area participating in the bonding was more important than the average interparticulate distance. </p><p>When studying the properties of microcrystalline cellulose and cellulose powder from the alga <i>Cladophora</i> sp., the cellulose fibril surface area estimated by solid-state NMR resulted in better correlations to the tableting behaviour and to tablet disintegration than the external permeametric surface area did. It was suggested that the difference in fibril surface area of the two celluloses was the primary factor responsible for properties like the crystallinity and the disintegration of the tablets.</p>

In this thesis, factors important in tableting operations and for tablet properties have been studied and characterised by different spectroscopic techniques as well as by some more conventionally used particle characterisation techniques. The spectroscopic techniques solid-state NMR, FT-IR and NIR spectroscopy, proved to be valuable tools in the estimation of particle and tablet properties, offering both specificity and sensitivity in the measurements. Because of the large amount of information obtained in a spectrum, multivariate data analysis was in some cases used in the processing of the spectral data. Correlations between the solid state structure measured by spectroscopy and the particle and tablet properties could be obtained including useful prediction models. The surface area obtained using different principles has in this thesis been shown to reflect different properties and tableting behaviour of a collection of pharmaceutical materials. The particle shape and the external surface area of the powders measured by permeametry, were found to be important factors for the tensile strength of tablets made of hydroxypropyl methylcellulose. Furthermore, the external surface area could be used to access dominating interparticulate bonding mechanisms in compacts of different materials by normalising the tablet tensile strength for the tablet surface area. It was also shown that for materials prone to develop solid bridges, the actual surface area participating in the bonding was more important than the average interparticulate distance. When studying the properties of microcrystalline cellulose and cellulose powder from the alga Cladophora sp., the cellulose fibril surface area estimated by solid-state NMR resulted in better correlations to the tableting behaviour and to tablet disintegration than the external permeametric surface area did. It was suggested that the difference in fibril surface area of the two celluloses was the primary factor responsible for properties like the crystallinity and the disintegration of the tablets.

Shadow shielding is a novel and practical concept for waste heat rejection from lunar surface spacecraft systems. A shadow shield is a light shield that shades the radiator from parasitic thermal radiation emanating from the sun or lunar surface. Radiator size and mass can reduce if the radiator is not required to account for parasitic heat loads in addition to system energy rejection requirements. The lunar thermal environment can be very harsh towards radiative heat rejection. Parasitic heat loads force the radiator to expand in size and mass to compensate. On the Moon, there are three types: surface infrared, solar insulation, and albedo. This thesis tests shadow shielding geometry and its effect on the radiator and nuclear reactor in a reactor-powered Carnot heat engine. Due to the nature of cooling by radiative heat transfer, the maximum shaft work a Carnot system can produce and the minimal required radiator area occurs when the Carnot efficiency is 25%. First, a case for shadow shielding is made using an isothermal, control radiator model in Thermal Desktop. Six radiator temperatures and three latitudes are considered in the tests. Test variables in this section include radiator shapes and shade geometry. The simulations found that shadow shielding is best suited for a low-temperature radiator at the lunar equator. Optimized parabolic shade geometry includes a focus right above or at the top of the radiator and full to three-quarters shade height. The most useful rectangular radiator shape for shadow shielding is that which has a low height and long width. All simulations were conducted using a shade with a 10 kg/m2 area mass. A sensitivity study was conducted for different shade area masses using high and low values found in the literature. The shade is the most useful when the shade's area mass is less than or equal to that of the radiator. If the shade mass is below this threshold, the shade would be applicable to all radiator temperatures tested. Optimized shade and radiator geometry results were then factored into a second model where the radiator is comprised of heat pipes which is similar to radiators from actual system designs. Further simulations were conducted implementing the SAFE-4001 fast fission nuclear reactor design. The study found that shadow shielding allowed the system to use a low-temperature radiator where other configurations were not viable because shadow shielding drastically improves radiative heat transfer from the radiator, but at the consequence of raising radiator mass.

There is a great need in the transportation industry for high strength, high stiffness and lightweight materials with excellent dimensional stability. The use of these materials reduces fuel consumption and greenhouse gas emission as well as malfunctioning of components when subjected to fluctuating temperatures. Metal matrix composites (MMCs) are designed to meet these needs of transportation and other industries. However, their use is limited by lack of information on their thermal behaviour. In addition, reactions that occur in MMCs alter their microstructure and properties. These reactions have been widely investigated using X-ray Diffractometry (XRD) and electron microscopy (EM). However, these techniques cannot provide information such as charge transfer and local elemental structures in materials. Synchrotron X-ray Absorption Spectroscopy (XAS) could be used to identify reaction products in MMCs as well as provide information which XRD and EM cannot provide.<p> The thermal behaviour of Al-Mg alloy A535 containing fly ash particles as well as charge transfer and reactivity in particulate aluminium alloy metal matrix composites (MMCs) were investigated in this work. The materials studied were (i) Al-Cu-Mg alloy AA2618 and its composites reinforced with 10 and 15 vol.% alumina (Al2O3) particles and (ii) Al-Mg alloy A535 and its composites reinforced with a mixture of 5 wt.% fly ash and 5 wt.% silicon carbide, 10 wt.% and 15 wt.% fly ash. The investigative techniques used included Differential Scanning Calorimetry (DSC), Thermomechanical Analysis (TMA), Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and synchrotron X-ray Absorption Spectroscopy (XAS).<p> The results obtained showed that the coefficient of thermal expansion (CTE) of A535 decreased with the addition of fly ash and silicon carbide. Also, the addition of these particles improved the dimensional stability of the alloy in that the residual strain, åp, cycling strain, åc, and CTE decreased. The results obtained from XAS measurements showed evidence of charge redistribution in the aluminium in AA2618 with the addition of alumina particles. The results obtained from XAS measurements showed evidence of charge redistribution in the aluminium in AA2618 with the addition of alumina particles. The addition of alumina particles into AA2618 increased the p-orbital population and also changed the surface chemistry of the matrix. It was also demonstrated that the XAS technique can be used to determine the presence of various oxides in industrial fly ash and spinel (MgAl2O4) in alumina and fly ash particles extracted from the MMCs.

Trimesoyl chloride (TMC) crosslinked poly(vinyl alcohol) (PVA) / chitosan (CS) membranes and synthetic polyimide membranes were prepared for pervaporation dehydration of isopropanol and gas separation. PVA membranes were interfacially crosslinked with different amounts of TMC/hexane, and the degree of crosslinking was characterized by Fourier Transform Infrared Spectroscopy - Attenuated Total Reflectance Spectroscopy (FTIR-ATR) and water uptake. The asymmetric structure of the PVA-TMC membranes was revealed by FTIR-ATR. Thermal analysis was performed to understand the pyrolysis mechanism, which was supposed to be a combination of elimination of water and/or trimesic acid followed by breakage of the main chain. Water permeation and pervaporation dehydration of isopropanol were conducted, and the results showed that PVA-3TMC had the best overall pervaporation properties among the four PVA-TMC membranes studied. Sorption properties and pervaporation behavior of the PVA-3TMC membrane were investigated. The effects of water/isopropanol on the polymer matrix and the possible change of the degree of crystallinity induced by the sorbed water were believed to account for the sorption properties. For water permeation and pervaporation dehydration of isopropanol in a heating-cooling cycle, the permeation flux did not change significantly, and the selectivity was improved by the formation of crystallites during the heating run. For pervaporation in the diluting and concentrating runs at 60 °C, there was no change in the membrane permeability. Chitosan membranes were interfacially crosslinked in TMC/hexane with different crosslinking time. The membrane with a higher degree of crosslinking showed a higher degree of swelling in water at room temperature. A two-stage thermal decomposition mechanism was proposed based on thermal analyses. Pure gas permeation was performed with CO2 and N2 at room temperature, and CS-TMC-2 showed the best performance, with a CO2 permeability of ~163 Barrer and a CO2/N2 permeability ratio of ~42. Pervaporation was carried out for dehydration of isopropanol with the unconditioned and conditioned membranes, and the CS-TMC-3 membrane showed the best pervaporation performance. Pervaporation and gas separation properties were affected by the crosslinking-induced relaxation and the mobility/packing properties of the CS-TMC matrices. 4,4'-(Hexafluoroisopropylidene) diphthalic anhydride (6FDA)-based and 2,2-bis[4-(3,4-dicarboxyphenoxy) phenyl]propane dianhydride (BPADA)-based copolyimides were synthesized from one-step high-temperature polymerization in m-cresol. Polymers were characterized with Gel Permeation Chromatography (GPC), FTIR, Nuclear Magnetic Resonance Spectroscopy (NMR), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Surface free energies and interfacial free energies were calculated from contact angles to characterize hydrophilicity of the polyimide membranes. Gas permeation properties of 6FDA-based copolyimide membranes were studied with N2, O2, H2, He and CO2, and pervaporation dehydration of isopropanol was performed with 6FDA-based and BPADA-based membranes. An empirical linear moiety contribution approach was proposed, and the moiety contribution factors were used to illustrate the effects of dianhydrides and diamines on permselectivities of the copolyimide membranes. Bulky side groups, flexibility of polymer main chains, structures of monomer moieties, and interactions between gas molecules and polymer chains were shown to affect gas permselectivities, while in pervaporation, both sorption and diffusion properties were affected by the interactions between penetrants and polymer matrices as well as the steric effects of monomer moieties.

Trimesoyl chloride (TMC) crosslinked poly(vinyl alcohol) (PVA) / chitosan (CS) membranes and synthetic polyimide membranes were prepared for pervaporation dehydration of isopropanol and gas separation. PVA membranes were interfacially crosslinked with different amounts of TMC/hexane, and the degree of crosslinking was characterized by Fourier Transform Infrared Spectroscopy - Attenuated Total Reflectance Spectroscopy (FTIR-ATR) and water uptake. The asymmetric structure of the PVA-TMC membranes was revealed by FTIR-ATR. Thermal analysis was performed to understand the pyrolysis mechanism, which was supposed to be a combination of elimination of water and/or trimesic acid followed by breakage of the main chain. Water permeation and pervaporation dehydration of isopropanol were conducted, and the results showed that PVA-3TMC had the best overall pervaporation properties among the four PVA-TMC membranes studied. Sorption properties and pervaporation behavior of the PVA-3TMC membrane were investigated. The effects of water/isopropanol on the polymer matrix and the possible change of the degree of crystallinity induced by the sorbed water were believed to account for the sorption properties. For water permeation and pervaporation dehydration of isopropanol in a heating-cooling cycle, the permeation flux did not change significantly, and the selectivity was improved by the formation of crystallites during the heating run. For pervaporation in the diluting and concentrating runs at 60 °C, there was no change in the membrane permeability. Chitosan membranes were interfacially crosslinked in TMC/hexane with different crosslinking time. The membrane with a higher degree of crosslinking showed a higher degree of swelling in water at room temperature. A two-stage thermal decomposition mechanism was proposed based on thermal analyses. Pure gas permeation was performed with CO2 and N2 at room temperature, and CS-TMC-2 showed the best performance, with a CO2 permeability of ~163 Barrer and a CO2/N2 permeability ratio of ~42. Pervaporation was carried out for dehydration of isopropanol with the unconditioned and conditioned membranes, and the CS-TMC-3 membrane showed the best pervaporation performance. Pervaporation and gas separation properties were affected by the crosslinking-induced relaxation and the mobility/packing properties of the CS-TMC matrices. 4,4'-(Hexafluoroisopropylidene) diphthalic anhydride (6FDA)-based and 2,2-bis[4-(3,4-dicarboxyphenoxy) phenyl]propane dianhydride (BPADA)-based copolyimides were synthesized from one-step high-temperature polymerization in m-cresol. Polymers were characterized with Gel Permeation Chromatography (GPC), FTIR, Nuclear Magnetic Resonance Spectroscopy (NMR), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Surface free energies and interfacial free energies were calculated from contact angles to characterize hydrophilicity of the polyimide membranes. Gas permeation properties of 6FDA-based copolyimide membranes were studied with N2, O2, H2, He and CO2, and pervaporation dehydration of isopropanol was performed with 6FDA-based and BPADA-based membranes. An empirical linear moiety contribution approach was proposed, and the moiety contribution factors were used to illustrate the effects of dianhydrides and diamines on permselectivities of the copolyimide membranes. Bulky side groups, flexibility of polymer main chains, structures of monomer moieties, and interactions between gas molecules and polymer chains were shown to affect gas permselectivities, while in pervaporation, both sorption and diffusion properties were affected by the interactions between penetrants and polymer matrices as well as the steric effects of monomer moieties.

There is a great need in the transportation industry for high strength, high stiffness and lightweight materials with excellent dimensional stability. The use of these materials reduces fuel consumption and greenhouse gas emission as well as malfunctioning of components when subjected to fluctuating temperatures. Metal matrix composites (MMCs) are designed to meet these needs of transportation and other industries. However, their use is limited by lack of information on their thermal behaviour. In addition, reactions that occur in MMCs alter their microstructure and properties. These reactions have been widely investigated using X-ray Diffractometry (XRD) and electron microscopy (EM). However, these techniques cannot provide information such as charge transfer and local elemental structures in materials. Synchrotron X-ray Absorption Spectroscopy (XAS) could be used to identify reaction products in MMCs as well as provide information which XRD and EM cannot provide.<p> The thermal behaviour of Al-Mg alloy A535 containing fly ash particles as well as charge transfer and reactivity in particulate aluminium alloy metal matrix composites (MMCs) were investigated in this work. The materials studied were (i) Al-Cu-Mg alloy AA2618 and its composites reinforced with 10 and 15 vol.% alumina (Al2O3) particles and (ii) Al-Mg alloy A535 and its composites reinforced with a mixture of 5 wt.% fly ash and 5 wt.% silicon carbide, 10 wt.% and 15 wt.% fly ash. The investigative techniques used included Differential Scanning Calorimetry (DSC), Thermomechanical Analysis (TMA), Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and synchrotron X-ray Absorption Spectroscopy (XAS).<p> The results obtained showed that the coefficient of thermal expansion (CTE) of A535 decreased with the addition of fly ash and silicon carbide. Also, the addition of these particles improved the dimensional stability of the alloy in that the residual strain, åp, cycling strain, åc, and CTE decreased. The results obtained from XAS measurements showed evidence of charge redistribution in the aluminium in AA2618 with the addition of alumina particles. The results obtained from XAS measurements showed evidence of charge redistribution in the aluminium in AA2618 with the addition of alumina particles. The addition of alumina particles into AA2618 increased the p-orbital population and also changed the surface chemistry of the matrix. It was also demonstrated that the XAS technique can be used to determine the presence of various oxides in industrial fly ash and spinel (MgAl2O4) in alumina and fly ash particles extracted from the MMCs.

This thesis presents the results of an experimental investigation into the behavior of a pultruded E-glass/polyester fiber reinforced polymer (FRP) composite under sustained loads at elevated temperatures in the range of those that might be seen in service. This investigation involved compression creep tests of material coupons performed at a constant stress level of 33% of ultimate strength and three temperatures levels; 23.3°C (74°F), 37.7°F (100°F), and 54.4°C (130°F). The results of these experiments were used in conjunction with the Findley power law and the Time- Temperature Superposition Principle (TTSP) to formulate a predictive curve for the longterm creep behavior of these pultruded sections. Further experiments were performed to investigate the effects of thermal cycles in order to better simulate service conditions.

Thermo-mechanical failure of components in planar-type solid oxide fuel cells (SOFCs) is a major obstacle on the path to bringing this technology to commercial viability. The probability of material degradation and failure in SOFCs depends strongly on the local temperature gradients at the interfaces of different materials. Therefore, it is of paramount importance to accurately predict and manage the temperature fields within the stack, especially near the interfaces. In this work we consider three effects in detail. First, we analyze radiative heat transfer effects within the semi-transparent solid electrolyte and compared them to thermal conduction. We also, present the modeling approach for calculation of surface-to-surface exchange within the flow channels and from the stack to the environment. The simplifying assumptions are identified and their carefully justified range of applicability to the problem at hand is established. This allows thermal radiation effects to be properly included in overall thermal modeling efforts with the minimum computational expense requirement. Second, we developed a series of reduced-order models for the transient heating and cooling of a cell, leading to a framework for optimization of these processes. The optimal design is one that minimizes heating time while maintaining thermal gradients below an allowable threshold. To this end, we formulated reduced order models (validated by rigorous CFD simulations) that yield simple algebraic design rules for predicting maximum thermal gradients and heating time requirements. Several governing dimensionless parameters and time scales were identified that shed light on the essential physics of the process. Finally, an analysis was performed to assess the degree of local thermal non-equilibrium (LTNE) within porous SOFC electrodes, and through a simple scaling analysis we discovered the parameter that gives an estimate of the magnitude of LTNE effects. We conclude that because of efficient heat transfer between the solid and gas in the microscale pores of the electrodes, the temperature difference between gas and solid is often negligible. However, if local variations in current density are significant, the LTNE effects may become significant and should be considered.

This work describes two closed-loop atomic force microscopy methods that utilize the heated silicon probe to interrogate surfaces. The first method identifies the softening temperatures of a selected polymer and organic substrate as a function of contact force and surface hardness. Motivation partly stems from nanosampling, which requires knowledge of phase-specific transitions to identify and extract mass from multicomponent systems for chemical analysis. In the second method, the cantilever is implemented as a Kelvin probe to study the effect of temperature on the measured contact potential. The objective is to ascertain whether the probe functions as a capable electrode for scanning Kelvin probe microscopy (SKPM) applications. This was achieved by performing heated force-distance experiments on a biased gold film with the tip operating at various potentials. Both experiments examine the interaction between the tip and substrate and analyze sample effects both induced and sensed by the cantilever.