Thesis (M.S.)--University of North Texas, May, 2007. / Title from title page display. Includes bibliographical references.

A relatively new type of reinforced composite material, derived from immiscible blends of thermoplastic homopolymers, is characterised in this doctoral research. Microfibril Reinforced Composites (MFCs) utilise common engineering and commodity polymers to create high strength and stiffness microfibrils dispersed in an isotropic matrix. Unlike traditional polymer composites, MFCs use the dispersed component of a blend to create an even distribution of in situ reinforcing microfibrils via a simple extrusion, drawing and processing technique. This research quantifies the mechanical and oxygen gas barrier properties of polyolefin-based MFCs containing polyethylene terephthalate (PET) microfibrils. It is concerned not only with identifying MFCs with the best properties, but also with how manufacturing parameters influence those properties. Characterisation is split into several parts. Initial investigations into blend development during extrusion and drawing were conducted. The main purpose of this was to gain a better understanding of the factors influencing the morphological changes that occur during production. Blend viscosity ratio and capillary number were identified as key factors in determining the onset of coalescence, deformation and break up of the dispersed polymer. The effects on microfibril formation of several important manufacturing parameters were highlighted, with die diameter and extrusion speed the most influential of these. A significant skin-core microstructure was observed. Formation of elongated microfibres (with negligible molecular chain alignment) was shown to occur during extrusion, which was subsequently justified via modelling of the shear stress flow fields in the die. Drawn blends gave very high tensile strengths and stiffnesses due to highly oriented molecular chains. A threshold draw ratio of 3.5, at which properties change considerably, was identified. Mechanical properties of injection moulded MFCs from polypropylene were not considerably better than the neat matrix polymer. However, those from polyethylene (PE) showed significant improvement via injection moulding and directional compression moulding. MFCs with just 30% microfibril content displayed tensile properties up to six times greater than neat PE. Measurements of oxygen gas permeability highlighted improvements of up to 65%. Processing and cooling conditions were shown to significantly influence permeability via a Taguchi experimental design analysis. MFC storage containers from PE/PET were injection moulded as proof-of-concept on completion of the research.

A relatively new type of reinforced composite material, derived from immiscible blends of thermoplastic homopolymers, is characterised in this doctoral research. Microfibril Reinforced Composites (MFCs) utilise common engineering and commodity polymers to create high strength and stiffness microfibrils dispersed in an isotropic matrix. Unlike traditional polymer composites, MFCs use the dispersed component of a blend to create an even distribution of in situ reinforcing microfibrils via a simple extrusion, drawing and processing technique. This research quantifies the mechanical and oxygen gas barrier properties of polyolefin-based MFCs containing polyethylene terephthalate (PET) microfibrils. It is concerned not only with identifying MFCs with the best properties, but also with how manufacturing parameters influence those properties. Characterisation is split into several parts. Initial investigations into blend development during extrusion and drawing were conducted. The main purpose of this was to gain a better understanding of the factors influencing the morphological changes that occur during production. Blend viscosity ratio and capillary number were identified as key factors in determining the onset of coalescence, deformation and break up of the dispersed polymer. The effects on microfibril formation of several important manufacturing parameters were highlighted, with die diameter and extrusion speed the most influential of these. A significant skin-core microstructure was observed. Formation of elongated microfibres (with negligible molecular chain alignment) was shown to occur during extrusion, which was subsequently justified via modelling of the shear stress flow fields in the die. Drawn blends gave very high tensile strengths and stiffnesses due to highly oriented molecular chains. A threshold draw ratio of 3.5, at which properties change considerably, was identified. Mechanical properties of injection moulded MFCs from polypropylene were not considerably better than the neat matrix polymer. However, those from polyethylene (PE) showed significant improvement via injection moulding and directional compression moulding. MFCs with just 30% microfibril content displayed tensile properties up to six times greater than neat PE. Measurements of oxygen gas permeability highlighted improvements of up to 65%. Processing and cooling conditions were shown to significantly influence permeability via a Taguchi experimental design analysis. MFC storage containers from PE/PET were injection moulded as proof-of-concept on completion of the research.

A relatively new type of reinforced composite material, derived from immiscible blends of thermoplastic homopolymers, is characterised in this doctoral research. Microfibril Reinforced Composites (MFCs) utilise common engineering and commodity polymers to create high strength and stiffness microfibrils dispersed in an isotropic matrix. Unlike traditional polymer composites, MFCs use the dispersed component of a blend to create an even distribution of in situ reinforcing microfibrils via a simple extrusion, drawing and processing technique. This research quantifies the mechanical and oxygen gas barrier properties of polyolefin-based MFCs containing polyethylene terephthalate (PET) microfibrils. It is concerned not only with identifying MFCs with the best properties, but also with how manufacturing parameters influence those properties. Characterisation is split into several parts. Initial investigations into blend development during extrusion and drawing were conducted. The main purpose of this was to gain a better understanding of the factors influencing the morphological changes that occur during production. Blend viscosity ratio and capillary number were identified as key factors in determining the onset of coalescence, deformation and break up of the dispersed polymer. The effects on microfibril formation of several important manufacturing parameters were highlighted, with die diameter and extrusion speed the most influential of these. A significant skin-core microstructure was observed. Formation of elongated microfibres (with negligible molecular chain alignment) was shown to occur during extrusion, which was subsequently justified via modelling of the shear stress flow fields in the die. Drawn blends gave very high tensile strengths and stiffnesses due to highly oriented molecular chains. A threshold draw ratio of 3.5, at which properties change considerably, was identified. Mechanical properties of injection moulded MFCs from polypropylene were not considerably better than the neat matrix polymer. However, those from polyethylene (PE) showed significant improvement via injection moulding and directional compression moulding. MFCs with just 30% microfibril content displayed tensile properties up to six times greater than neat PE. Measurements of oxygen gas permeability highlighted improvements of up to 65%. Processing and cooling conditions were shown to significantly influence permeability via a Taguchi experimental design analysis. MFC storage containers from PE/PET were injection moulded as proof-of-concept on completion of the research.

A relatively new type of reinforced composite material, derived from immiscible blends of thermoplastic homopolymers, is characterised in this doctoral research. Microfibril Reinforced Composites (MFCs) utilise common engineering and commodity polymers to create high strength and stiffness microfibrils dispersed in an isotropic matrix. Unlike traditional polymer composites, MFCs use the dispersed component of a blend to create an even distribution of in situ reinforcing microfibrils via a simple extrusion, drawing and processing technique. This research quantifies the mechanical and oxygen gas barrier properties of polyolefin-based MFCs containing polyethylene terephthalate (PET) microfibrils. It is concerned not only with identifying MFCs with the best properties, but also with how manufacturing parameters influence those properties. Characterisation is split into several parts. Initial investigations into blend development during extrusion and drawing were conducted. The main purpose of this was to gain a better understanding of the factors influencing the morphological changes that occur during production. Blend viscosity ratio and capillary number were identified as key factors in determining the onset of coalescence, deformation and break up of the dispersed polymer. The effects on microfibril formation of several important manufacturing parameters were highlighted, with die diameter and extrusion speed the most influential of these. A significant skin-core microstructure was observed. Formation of elongated microfibres (with negligible molecular chain alignment) was shown to occur during extrusion, which was subsequently justified via modelling of the shear stress flow fields in the die. Drawn blends gave very high tensile strengths and stiffnesses due to highly oriented molecular chains. A threshold draw ratio of 3.5, at which properties change considerably, was identified. Mechanical properties of injection moulded MFCs from polypropylene were not considerably better than the neat matrix polymer. However, those from polyethylene (PE) showed significant improvement via injection moulding and directional compression moulding. MFCs with just 30% microfibril content displayed tensile properties up to six times greater than neat PE. Measurements of oxygen gas permeability highlighted improvements of up to 65%. Processing and cooling conditions were shown to significantly influence permeability via a Taguchi experimental design analysis. MFC storage containers from PE/PET were injection moulded as proof-of-concept on completion of the research.

This thesis presents the research of packaging beer into plastic bottles and the design and manufacture of a low pressure bottle blow moulding machine for demonstration purposes. The machine will be used for the production of plastic bottles suitable for bottling brewed beer at the microbrewery at Massey University Palmerston North. Premanufactured PET preforms have proven to be the most convenient and promising choice for the fabrication of blown bottles. Basic tests to understand the behaviour of the preforms and the challenges of the blowing process have been carried out. A special focus has been placed on the different circumstances at University in contrast to industrial bottle production in particular the needed air pressure to form the bottles. The following step was to find the ideal method and principle to handle the preforms and to transform them in the desired shape. Finally the design, drawing of the parts and assemblies were carried out with the 3-D CAD software Solidworks. The designed parts for the bottle blower have been manufactured at the mechanical Workshop at Massey University. To control the bottle blower, the National Instruments USB interface was selected which required the design and manufacture of an additional driver interface card to protect the USB interface and convert the TTL levels into higher voltage. The final assembly and testing of the blower then concluded the practical work for this master project. A suitable design for the bottle production was found and the assembled Bottle Blower can now be used for the production of PET bottles.

This thesis describes an investigation into the flow behaviour of particulate solids and capsules in wood pulp fibre suspensions. Emphasis is placed on measuring pipe friction loss and stability of solids-fibre slurries and fibre-capsule mixtures in straight horizontal pipes. It is shown that low concentrations (1-3 %v) of wood pulp fibre form a structured carrier fluid with ability to support particles while behaving like a liquid of low viscosity. At moderate flow velocities fibres damp turbulence and friction losses become lower than water. If solids are preferentially injected into the fibre suspension as a central core, or in a capsule as dry solids, pipe friction loss is reduced further, as is pipe wear. At very low fibre concentrations (<1%v), fibres reduce the friction loss of conventional solid-water mixtures and act as a drag reducing additive. The network strength properties of five wood fibre suspensions are reported and their application to slurry flow is discussed. Settling data for particulate solids, coherent dense-phase cores and capsules are presented and various mechanisms of support are described. Two flow techniques for transporting coarse and dense-phase particle suspensions are proposed, along with strategies for injecting solid particulates into a pipeline. Pipe friction loss data are presented for solids-fibre mixtures of wood chips (7-15 mm), coarse (+2-10 mm) and fine (+0.5-1.0 mm) coal, sand (+0.32-2.0 mm), iron ore (+0.05-0.28 mm), and cylindrical capsules (loaded with dry solids) flowing in 54, 79 and 101.6 mm diameter PVC pipes. Some pipe friction loss data are presented for solids transported as a central core supported by an annulus of fibre suspension. The key flow parameters are also optimized and a preliminary cost comparison is made. Coarse coal suspensions (up to 4O %v) with fibre concentrations of 0.7 to 1.0 percent have been shown to exhibit friction losses about 40 percent below that of the equivalent coalwater slurry. Adding 0.8 percent fibre to water is shown to reduce capsule friction head loss up to 50 percent.

Thermal spray is a well established technology that is commonly used in the aerospace and automotive industries. This thesis reports on the effect that substrate surface chemistry, morphology and temperature has on the morphology of PEEK single splats on aluminium substrates. PEEK single splats were deposited by HVAF and plasma spraying on aluminium substrates with 6 different pretreatments. Substrates were either sprayed at room temperature, or 323°C, and a subset of substrates was held at incremental temperatures up to 363°C. HVAF deposited splats on room temperature substrates showed sensitivity to surface chemistry, with increased circularity and area associated with low levels of hydroxide and chemisorbed water on the aluminium surface. Substrates held at 323°C were more sensitive to substrate morphology, where rough surfaces resulted in decreased circularity and area apparently independent of surface chemistry. Substrate temperature trials revealed a significant step in the results, equating to greater circularity, and lower splat area, perimeter and Feret diameter. This step occurred between 123°C and 163°C, the two points bracketing the glass transition temperature of PEEK (143°C). This result was due to the relaxation of splats deposited on surfaces above 143°C, whilst splats on cooler substrates quench through the glass transition and do not relax. PEEK splats deposited by plasma spray on room temperature and 323°C substrates showed sensitivity to the amount of hydroxide and chemisorbed water present on the aluminium substrates, with low levels resulting in more circular and larger area splats. Plasma splats did not show the same temperature effects as HVAF splats, thought to be due to the more molten state of plasma splats upon impact compared to the HVAF splats. The primary conclusions reached were that plasma sprayed polymers were sensitive to surface chemistry, and that as such the surface chemistry of a substrate should be considered when forming plasma spray polymer coatings. It was also concluded that the kinetic energy of particles in HVAF thermal spray contributed significantly to the thermal energy of a particle on impact, allowing for improved splat properties without overheating the particles in flight. Finally it was concluded that substrate temperature is far more important for HVAF thermal spray of polymers than plasma spray of polymers, but that it improves splat properties for both techniques.

Whole document restricted, see Access Instructions file below for details of how to access the print copy. / Articular cartilage functions successfully as a compression load-bearing tissue by virtue of the functional interplay between a 3-dimensional structure of collagen fibrils and the entrapped water-swollen proteoglycan molecules. Crucial to this entrapment process is a mechanism or set of mechanisms that maintain the collagen fibrils in a finely divided interconnected configuration that immobilises the macro-molecular proteoglycan complexes. Any loss of interconnectivity in the collagen network that might reduce the constraints on the swelling tendency of the proteoglycan domains will lead to a lower matrix stiffness. There are some structural similarities between this less stiff or abnormally softened cartilage and the degenerative osteoarthritic matrix, although ultrastructural studies to date are somewhat limited. The primary objective of the research reported in this thesis was to investigate the fibrillar architecture in the general matrix of both the normal and abnormally softened cartilage matrices. The fibrillar architectures of the normal and abnormally softened general matrices were compared using Nomarski light microscopy (LM), transmission electron microscopy (TEM) with combined stereoscopic reconstruction, and scanning electron microscopy (SEM). As reported earlier by Broom (1984b), a pseudo-random network developed from an overall radial arrangement of collagen fibrils is the most fundamental ultrastructural characteristic of the normal general matrix. By contrast, this present investigation has shown that the most distinctive feature of the softened matrix is the presence of parallel and relatively unentwined fibrils, strongly aligned in the radial direction. A structural model illustrating the transformation from the normal to the softened matrix is proposed based on the important property of lateral interconnectivity in the fibrils which involves both entwinement and non-entwinement based interactions. The distribution of proteoglycans in the normal and the softened matrix was compared. The distribution of Type II collagen was investigated using immunohistochemical staining combined with confocal imaging. It is concluded that the Type II fibrils do persist in the altered matrix thus adding further experimental support for the proposed transformation model. The swelling behaviour of the general matrix of both normal and abnormally softened articular cartilage was compared by subjecting tissue specimens under different modes of constraint to a high swelling bathing solution of distilled water and comparing structural changes imaged at the macroscopic, microscopic and ultramicroscopic levels of resolution. Near-zero swelling was observed in the isolated normal general matrix with minimal structural change. By contrast, the similarly isolated softened general matrix exhibited large-scale swelling in both the transverse and radial directions. This difference in dimensional stability was attributed to fundamentally different levels of fibril interconnectivity between the two matrices. The structural transformation model was further developed to accommodate fibrillar rearrangements associated with the large-scale swelling in the radial and transverse directions in the softened general matrix.

This thesis describes an investigation into the flow behaviour of particulate solids and capsules in wood pulp fibre suspensions. Emphasis is placed on measuring pipe friction loss and stability of solids-fibre slurries and fibre-capsule mixtures in straight horizontal pipes. It is shown that low concentrations (1-3 %v) of wood pulp fibre form a structured carrier fluid with ability to support particles while behaving like a liquid of low viscosity. At moderate flow velocities fibres damp turbulence and friction losses become lower than water. If solids are preferentially injected into the fibre suspension as a central core, or in a capsule as dry solids, pipe friction loss is reduced further, as is pipe wear. At very low fibre concentrations (<1%v), fibres reduce the friction loss of conventional solid-water mixtures and act as a drag reducing additive. The network strength properties of five wood fibre suspensions are reported and their application to slurry flow is discussed. Settling data for particulate solids, coherent dense-phase cores and capsules are presented and various mechanisms of support are described. Two flow techniques for transporting coarse and dense-phase particle suspensions are proposed, along with strategies for injecting solid particulates into a pipeline. Pipe friction loss data are presented for solids-fibre mixtures of wood chips (7-15 mm), coarse (+2-10 mm) and fine (+0.5-1.0 mm) coal, sand (+0.32-2.0 mm), iron ore (+0.05-0.28 mm), and cylindrical capsules (loaded with dry solids) flowing in 54, 79 and 101.6 mm diameter PVC pipes. Some pipe friction loss data are presented for solids transported as a central core supported by an annulus of fibre suspension. The key flow parameters are also optimized and a preliminary cost comparison is made. Coarse coal suspensions (up to 4O %v) with fibre concentrations of 0.7 to 1.0 percent have been shown to exhibit friction losses about 40 percent below that of the equivalent coalwater slurry. Adding 0.8 percent fibre to water is shown to reduce capsule friction head loss up to 50 percent.