Slip casting is a well established technique for the manufacture of traditional ceramic bodies, such as clays and whitewares. It combines complex shaping with high green densities, resulting in low shrinkage and good densification behaviour. / This method, however, has received little attention in the field of engineering ceramics especially with regard to silicon nitride. Commercial fabrication of silicon nitride, a major contender for high temperature applications due to its excellent thermomechanical properties, has been confined to hot pressing. This is an expensive process and has geometrical limitations. / Slip casting, followed by sintering, has been identified as a potentially economical alternative fabrication method, however a number of parameters have to be optimized before a good slip cast silicon nitride body can be made. The aim of the present work is to control parameters such as pH, viscosity and deflocculation in order to form dense, homogeneous, slip cast silicon nitride bodies. / A detailed investigation of the rheological properties of Si$ sb3$N$ sb4$ and careful control of processing parameters, made it possible to produce slip cast Si$ sb3$N$ sb4$ bodies having up to 97% TD on sintering. Mechanical strength values obtained by slip casting were compared with those obtained by die-pressing. Strength values of the slip cast material was limited by iron inclusions entrained in processing.

Blends of cellulose (CELL) with polyvinyl pyrrolidone (PVP), poly(4-vinyl pyridine) (P$ sb4$VPy), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), poly($ epsilon$-caprolactone) (PCL), and nylon 6 (Ny6), and of chitosan with PVA were investigated in an attempt to gain some insight into the factors that affect the miscibility of cellulose with synthetic polymers. The miscibility and the scale of mixing of the various blends were studied by differential scanning calorimetry, dynamic mechanical analysis, infrared and NMR spectroscopy, and proton spin-lattice relaxation measurements. The CELL/PVP, CELL/P$ sb4$VPy, and chitosan/PVA blends were shown to be homogeneous at the molecular level, while the CELL/PAN blends were shown to mix on a larger scale. In contrast the CELL/PCL and CELL/Ny6 blends were essentially immiscible; from this it was concluded that the potential for strong inter-molecular interactions is not a sufficient condition for miscibility to occur in cellulose/synthetic-polymer blends.

The society is becoming increasingly more energy and environmentally conscientious, which has forced development of construction materials, which are both inexpensive and require very little energy to produce. One way of producing such materials is to utilize by-products of industrial processes. High-volume fly ash cement based grouts are tributary of such developements. / This thesis outlines the results of a detailed study of the grain size distribution, three rheological properties and five mechanical properties of high-volume fly ash grouts (60% cement replacement for fly ash by weight) with or without the use of superplasticizers and/or anti-washout agents. The rheological properties are reported for eight water/cement + fly ash (water/solids) ratios. The effect of superplasticizers and anti-washout agents on the flow time of low water/solids ratio grouts and the stability of high water/solids ratio grouts are investigated. / The study revealed that: (1) The addition of fly ash reduces significantly the flow time of low water/solids ratio grouts (0.4 to 0.65). (2) The stability of cement grout is improved by the addition of fly ash for water/solids ratios greater than or equal to 0.65. (3) The use of fly ash reduces the early compressive and bond strength, when compared to the reference grout (pure cement). However, as they mature their strengths are closer to those of the pure cement grouts. (4) Fly ash reduces the amount of drying shrinkage compared to pure cement grout with an equivalent water/solids ratio.

A new synthetic route to silylhydrazine molecules and polymers has been developed by the heterodehydrocoupling of organosilanes with hydrazines. A dimethyltitanocene catalyst has been employed to facilitate the dehydrocoupling reaction. The dehydrocoupling was shown to proceed by stepwise replacement of Si-H with hydrazino groups. The controlled hydrolysis of Ph$ sb2$Si(NHNHMe)$ sb2$ formed a hydrazinodisiloxane. Cyclizations of Ph$ sb2$Si(NHNHMe)$ sb2$ to form cyclic silylhydrazines were achieved by the reaction with n-BuLi/Ph$ sb2$SiCl$ sb2,$ or MeI (or HCl or Ph$ sb2$SiCl$ sb2),$ or thermolysis. Crystal structures of Ph$ sb2$Si(NHNR)(NRNH)SiPh$ sb2$ (R = H, Me) reveal chair (R = H) and twist-boat (R = Me) conformations of the Si$ sb2$N$ sb4$ ring, respectively. Planar and pyramidal nitrogen geometries were found to coexist in a hydrazino unit. A preceramic polymer, synthesized by the polymerization of MeHSiCl$ sb2$ with hydrazine in an appropriate ratio, was pyrolyzed to Si$ sb3$N$ sb4$/SiC$ rm sb{x}$N$ rm sb{y}$ in 67-80% ceramic yields. It is proposed that the structural unit of this polymer is a tetraazadisilacyclohexane bridged by MeHSi groups. This assignment is based on $ sp{1}$H and $ sp{29}$Si NMR measurements, as well as by comparison with the well-defined reaction product of Me$ sb2$Si(NHNH) $ sb2$SiMe$ sb2$ with MeHSiCl$ sb2.$ The pyrolysis was carried out from room temperature to 1500$ sp circ$C under argon and studied by using thermogravimetric analysis, solid-state $ sp{29}$Si NMR spectroscopy, infrared spectroscopy, x-ray powder diffraction, and elemental analysis. Serial structural changes were characterized in the pyrolyzed solid products. The ceramic product of this polymer at 1100$ sp circ$C was found to possess a quasi-metallic electrical conductivity ($ sigma$ = 10$ sp3$ ($ Omega$cm)$ sp{{-}1}),$ and was evaluated as an electrode material.

Optical properties of polyethylene blown films are of great commercial and scientific interest. An understanding of the relationship between morphology and optical properties will have a significant impact on product and process optimization. / In this work, a number of linear low density polyethylene (LLDPE) resins of different molecular and structural characteristics were studied. Intrinsic properties such as refractive index and absorption coefficient were estimated from resin compositions using group contribution models. The refractive indices of sample films were also measured using the method of Transmission Spectrum. / The morphology of polyethylene films was investigated using Atomic Force Microscopy (AFM) and Near-field Scanning Optical Microscopy (NSOM). Both the surface and bulk morphologies were evaluated. The observation shows the dominant spherulitic structure on the surface as well as in the bulk, as the result of nucleation and crystallization during the film blowing process. In addition to qualitative observations and comparisons; quantitative characterization methods were employed to describe the features of the morphology. / Based on the morphology characterization, the surface reflection was described by the Beckmann-Davies theory of reflection of electro-magnetic waves by rough surface. The directional distribution of reflected intensity was computed according to the surface roughness information. The gloss values of sample films were computed accordingly and compared with experimental measurements. Furthermore, the problem of light transmission and scattering was investigated. A scattering geometry was proposed from the observations of the morphology of sample films. The light scattering by the surface of polymer films was analyzed using a model that is based on the Mie theory of scattering. The haze values of sample films were computed and compared with experimental measurements.

One of the major setbacks of ceramic materials is their inherent brittle nature which often leads to catastrophic failure, especially under impact and tensile stress conditions. Whisker-reinforcement of ceramic matrices has been shown to be an effective way of increasing toughness. However, the hot-pressing techniques being used at present are expensive. Si$ sb3$N$ sb4$ is a major contender for high temperature application, mainly due to its excellent mechanical, chemical and thermal properties. / In this work Si$ sb3$N$ sb4$ whiskers have been incorporated into a Si$ sb3$N$ sb4$ matrix and densified using pressureless sintering. An isotropic distribution of whiskers in the starting powder was seen to inhibit shrinkage of the bulk material as a result of whisker bridging. / An extrusion process was developed to align the whiskers such that they do not impinge on one another. This was done using a water soluble, cellulose based plasticizer. The process was sensitive to water content and mixing. Entrapped air caused problems in the extrudate, resulting in misaligned areas in the microstructure. Relative densities of 94.5% were obtained for composites having 15% whiskers. The toughness of this material was measured to be 13.5MPa.m$ sp{1/2}$ in the direction perpendicular to the direction of extrusion.

The influence of carbon (C) content, microstructure, crystallography and mechanical properties on the wear behaviour of metal-on-metal (MM) hip implants made from commercially available cobalt-chromium-molybdenum (CoCrMo) alloys designated as American Society of Testing and Materials (ASTM) grade F1537, F75 and as-cast were studied in this work. The as-received bars of wrought CoCrMo alloys (ASTM F1537 of either about 0.05% or 0.26% C) were each subjected to various heat treatments to develop different microstructures. Pin and plate specimens were fabricated from each bar and were tested against each other using a linear reciprocating pin-on-plate apparatus in 25% by volume bovine serum solution. The applied normal load was 9.81 N and the reciprocating plate had a sinusoidal velocity with an average speed of 26 mm/s. The wear was measured gravimetrically and it was found to be most strongly affected by alloy C content, irrespective of grain size or carbide morphology. More precisely, the wear behaviour was directly correlated to the dissolved C content of the alloys. Increased C in solid-solution coincided with lower volumetric wear since C helps to stabilize the face-centred cubic (FCC) crystal structure thus limiting the amount of strain induced transformation (SIT) to the hexagonal close-packed crystal structure (HCP). Based on the observed surface twinning in and around the contact zone and the potentially detrimental effect of the HCP phase, it was postulated that the MM wear behaviour of CoCrMo alloys in the present study was controlled by a deformation mechanism, rather than corrosion or tribochemical reactions.

The behaviour of slab-column connections in flat plates is investigated. The first part of this thesis discusses six two-way slab-column specimens which were designed such that they would fail in punching shear. The parameters investigated were the placement of fibre-reinforced concrete in the slab and the concentration of slab reinforcement around the column. The effects of these parameters on the punching shear capacity, negative moment cracking, and stiffness of the two-way slab specimens were investigated. / The second part of this thesis investigates the effects of the same parameters on six slab-column specimens and six column specimens without the surrounding slab for their ability to transmit axial loads from the high-strength concrete columns through the normal-strength concrete slab. / Currently there is no beneficial effect in the CSA code for using fibre-reinforced concrete or concentrated slab reinforcement near the column in the calculation for the punching shear resistance or for the transmission of loads through slab-column connections. The beneficial effects of concentrating the slab reinforcement near the column and of using fibre-reinforced concrete are demonstrated.

Fullerenes, the family of large, all-carbon, cage-like molecules, promise to launch an array of new products. However, the development of such products is hindered due to unavailability of large quantities of fullerenes and the present high cost of production. Fullerenes are produced commercially via the arc vaporization of graphite, a method which is limited to low production rates and low scale-up potential. In this work, a new process was developed in which fullerenes are produced via the thermal plasma dissociation of hydrocarbons. The process is attractive due to its potential for large scale fullerene production. Tetrachloroethylene (C2Cl4) was selected as the carbon source for fullerene synthesis, due to the instability of C-Cl bonds in the high temperature zone predicted for fullerene formation. / The effect of input electrical power, C2Cl4 feed rate and reactor pressure on fullerene formation and collection was studied. The temperature profile and its effect on the residence time of reactive species in the temperature zone required for fullerene formation was found to play a critical role in the production of fullerenes. With the present reactor configuration, an input power in excess of 55 kW was required for the treatment of up to 0.54 mol/min of C2Cl4. High C2Cl 4 feed rates resulted in a lower conversion of C2Cl 4 to fullerenes. Lower reactor pressures (200 and 300 torr) resulted in higher fullerene yields as compared to results obtained at 400 torr. The maximum concentration of fullerenes in soot was 5.3% and the maximum conversion of C2Cl4 to fullerenes was 2.8%, based on carbon input. / Fullerenes produced by the process were purified using conventional extractive and chromatographic techniques. Although successful, purification by chromatography proved to be difficult due to the presence of perchlorinated, aromatic by-products. Some of these perchlorinated aromatic by-products were identified and were found to have structures reminiscent of fullerene precursors, and thus, may provide clues as to how fullerenes form in this plasma process.

The electrical and electrochemical properties of self-assembled n-alkylthiol monolayers (SAMs) on gold are important if SAMs are to be used as molecular building blocks in biomimetic membranes and in micro- or nano-electronics. Ion transport and electron transfer at SAM/electrolyte interfaces are two important processes which have been characterized by cyclic voltammetry and a.c. impedance spectroscopy. Ion transport from an aqueous phase to the hydrophobic SAM region has been addressed by investigating the insulating properties of a wide variety of X(CH2)nS/Au SAMs (X = CH3, OH, CO2H and CF 3, and n = 7, 9, 11, 15). It was established that when the phase angle at a frequency characteristic of ion diffusion processes ( i.e. 1 Hz) is >88°, the SAM is defect-free and obeys the Helmholtz ideal capacitor model. However, when &phiv;1HZ < 88°, the SAM is no longer an ionic insulator and ion/water penetration from the electrolyte into the SAM hydrophobic region is observed. The behavior of the phase angle with frequency was used to characterize the permeability of SAMs to electrolyte ions (K+, H2PO4 -, and HPO42-) as a function of the applied d.c. potential. A critical potential, Vc, was identified for each type of SAM corresponding to a transition from an insulating state to a more permeable state. When X = CH3, V c becomes more cathodic with increasing chainlength, i.e. Vc = -0.15 V (vs. Ag/AgCl) for n = 7, -0.25 V for n = 9, 11, and -0.35 V for n = 15. The SAM ionic permeability can also be modulated by maintaining n constant (15) and by varying the terminal group X. Vc is considerably more anodic for hydrophilic SAM/electrolyte interfaces (+0.25 V vs . Ag/AgCl for X = OH and + 0.15 V for X = CO2H) than for hydrophobic interfaces (-0.35 V for X = CH3). The kinetics of electron transfer at CH3(CH2)15CH3 SAMs have been investigated by a.c. impedance spectroscopy at various d.c. overpotentials with three redox couples, Ru(NH3)63+/2+, Fe(CN)63-/4-, and Co(b