Thesis (Ph. D.)--Institute of Paper Chemistry, 1962. / Includes bibliographical references (p. 161-164).

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 120-125). Also available in electronic version. Access restricted to campus users.

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I describe an experimental apparatus used to perform deformation experiments relevant to volcanology. The apparatus supports low-load, high-temperature deformation experiments under dry and wet conditions on natural and synthetic samples. The experiments recover the transient rheology of complex (melt ± porosity ± solids) volcanic materials during uniaxial deformation. The key component to this apparatus is a steel cell designed for high-temperature deformation experiments under controlled water pressure. Experiments are run under constant displacement rates or constant loads; the range of accessible experimental conditions include: 25 - 1100 °C, load stresses 0 to 150 MPa, strain rates 10⁻⁶ to 10⁻² s⁻¹, and fluid pressures 0-150 MPa. I present a suite of high-temperature, uniaxial deformation experiments performed on 25 by 50 mm unjacketed cores of porous Φ∼0.8) sintered rhyolitic ash. The experiments were performed at, both, atmospheric (dry) and elevated water pressure conditions (wet). Dry experiments were conducted mainly at 900 °C, but also included a suite of lower temperature experiments at 850, 800 and 750 °C. Wet experiments were performed at ∼650 °C under water pressures of 1, 2.5, 3, and 5 MPa, and at a fixed PH2O of ∼2.5 MPa for temperatures of ∼385, 450, and 550 °C. During deformation, strain is manifest by shortening of the cores, reduction of porosity, flattening of ash particles, and radial bulging of the cores. The continuous reduction of porosity leads to a dynamic transient strain-dependent rheology and requires strain to be partitioned between a volume (porosity loss) and a shear (radial bulging) component. The effect of increasing porosity is to expand the window for viscous deformation for dry melts by delaying the onset of brittle deformation by ∼50 °C (875 °C to 825 °C). The effect is more pronounced in hydrous melts (∼0.67 — 0.78 wt. % H₂0) where the viscous to brittle transition is depressed by ∼140 to 150 °C. Increasing water pressure also delays the onset of strain hardening due to compaction-driven porosity reduction. These rheological data are pertinent to volcanic processes where high-temperature porous magmas I liquids are encountered (e.g., magma flow in conduits, welding of pyroclastic materials).

Taken as an engineering material, mozzarella cheese can be considered as a complex food system that has dynamic structure and complex flowproperties. Food scientists have been actively developing methods to characterize mozzarella cheese rheologically, but most of these methods are empirical in nature. In the past decades, there has been a paradigm shift towards the utilization of well-developed rheological methods which have been widely applied in the study of commercial synthetic polymers. In this work, the rheology of mozzarella cheese was studied using well-developed rheological techniques. Utilizing various rheometers, the linear and non-linear rheology of mozzarella cheese was examined. General practical properties of mozzarella cheese such as meltability, flowability and stretchability were extracted from these results. Capillary flow and rolling experiments were also performed to determine their suitability as innovative post-production processing techniques for mozzarella cheese. Finally, a comparative study on the effect of frozen storage on the rheology of three different brands of mozzarella cheese was performed. In general, it was found that mozzarella cheese can be classified as a pseudoplastic (shear thinning) semi-solid material possessing a yield stress at room temperature. Upon heating, the yield stress gradually diminishes and it can be considered as a viscoelastic fluid. The results obtained from the various rheometers indicate that the yield stress, duration of experiment, sample geometry and temperature greatly affect the consistency of the results. It was also shown that extrusion can be used as a processing technique for mozzarella cheese above a certain temperature where the cheese is in a melt state. Rolling was also found to be a potentially feasible processing method. Finally, in terms of the effect of frozen storage, in general, the dynamic moduli decrease with the period of storage due to the freezing of the proteins in the cheese.