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Increased understanding of plasma-polymer interactions is required to further the technological use of such processes, and elucidates heterogeneous physico-chemical reactions which occur under bombardment by complex combinations of energetic species. This thesis presents a systematic investigation into the effect of exposing organic and inorganic polymeric surfaces to controlled non-isothermal plasmas. Concurrently, a novel process is presented by which metal oxide gas barrier coatings are synthesized on polymer substrates by non- isothermal plasma treatment. Organic polymers exhibiting a range of structures were modified using non-isothermal plasmas at atmospheric and low pressure. The extent of atmospheric discharge oxygenation, measured by X-ray photoelectron spectroscopy (XPS), correlated with the polymers' ozonolysis rate constants. Surface physical disruption, studied using atomic force microscopy (AFM), after atmospheric discharge treatment was more pronounced than after low pressure plasma treatment. During low pressure oxygen plasma treatment, polymers containing phenyl groups were oxygenated to an extent which varied with the strength of π-π* valence band excitation in XPS C(1s) spectra of the untreated polymers, suggesting a dominance of reaction of plasma atomic oxygen at polymer radical sites excited by plasma vacuum ultraviolet radiation. The size of globules, observed by AFM, on the plasma modified surfaces correlated with the extent of surface chemical modification, inkeeping with a mechanism of chemically driven agglomeration of plasma oxidized low molecular weight polymer material. Oxygen plasma was more effective than water plasma in chemically modifying the surface of films of zirconium-normal-butoxide spin coated on polyester substrates, and the resulting optimized treatment produced a significant reduction in gas permeation of the substrate. XPS studies showed that oxygen plasma treatment of a polyphenylsilsesquioxane film on polyester film created a SiO(_2) layer less than 8 nm thin, which reduced O(_2) and Ar permeation of the coated film by 37.5 % and 31.6% respectively.

The primary objective for this creative project is to develop a series of wheel-thrown and altered ceramic sculptures that reflect my intuitive formation process. Although the work was influenced by a wide variety of outside sources, much of the impetus was born of my personal reflections on the concept of physical touch. My actions during the creation process were governed by sensory information absorbed mostly through my hands on the clay, and enhanced by inherent properties of the material. These preliminary experiences eventually sparked a desire to share this discovery with the viewer in the same tactile way. I further wished to include observers in the exhibit in a more direct and physical way, offering participants opportunities to explore their own sense of touch and consider how they relate to the objects around them. This body of work is an in-depth study of my intuitive creative process, a model for exploring the relationships between process and materials, and a means of providing observers of visual art a chance to connect with a visual object in a tactile way. / Department of Art

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The success of orthopaedic implants fixed in the skeletal system using bone ingrowth into porous surfaces is critically dependent on the extent and quality of the initial bone ingrowth and the subsequent long-term maintenance of the bone within the porous structure. Biologically-significant elements (Ca, Mg, Mn) were incorporated at concentrations up to 5 mol% in solid solution in yttia-stabilised tetragonal zirconia polycrystal (3YTZP), whilst controlling microstructure and phase composition, to investigate the effect of ceramic chemistry on cellular behaviour in vitro and bone ingrowth into porous structures in vivo. Cellular attachment, proliferation, and migration on the ceramics were investigated using in vitro assays using fibroblasts. Cells were able to adhere strongly and proliferate on all ceramic surfaces, exhibiting maximal proliferation and minimal migration on 3YTZP but significantly faster migration on doped-3YTZP. The TZP ceramics were therefore considered to support normal cellular processes and thus were suitable for further study in vivo. A technique based on pressure casting ceramic slurry into a polymer preform of the desire pore structure, followed by polymer burnout and then sintering, was developed for fabricating porous bioceramics containing highly-controlled three-dimensional pore geometries. The ability of a selected pore structure to support bone ingrowth was tested using hydroxyapatite by implanting samples into femoral cortical bone of adult sheep for 4 and 12 weeks. Bone was able to rapidly colonise the porous structure and remodel such that, by 12 weeks implantation time, the majority of the porosity was filled with mature lamellar bone. Porous scaffolds of pure 3YTZP and 3YTZP doped with 1 mol% Mg, 1 mol% Mn, 1 mol% Ca, or 5 mol% Ca were fabricated and tested in the sheep model. Bone ingrowth into the doped compositions was significantly greater than that into pure 3YTZP, and was similar to that into the porous hydroxyapatite, indicating that the dopants significantly promoted osteogenesis within the bioinert scaffolds. This finding has application in clinical applications in that the initial bone ingrowth and, potentially, the long-term maintenance of bone within the porous structure may be improved by the incorporation of small amounts of biologically significant elements.

Thesis (M.S.)--Ohio University, June, 1988. / Title from PDF t.p.