Wood Plastic Composites (WPCs) have experienced a healthy growth during the last decade. However, improvement in properties is necessary to increase their utility for structural applications. The toughness of WPCs can be improved by creating a fine cellular structure while reducing the density. Extrusion processing is one of the most economical methods for profile formation. For our study, rectangular profiles were extruded using a twin-screw extrusion system with different grades of HDPE and with varying wood fibre and lubricant contents together with maleated polyethylene (MAPE) coupling agent to investigate their effects on WPC processing and mechanical properties. Work has been done to redesign the extrusion system setup to achieve smoother and stronger profiles. A guiding shaper, submerged in the water, has been designed to guide the material directly through water immediately after exiting the die; instead of passing it through a water cooled vacuum calibrator and then through water. In this way a skin was formed quickly that facilitated the production of smoother profiles. Later on chemical blowing agent (CBA) was used to generate cellular structure in the profile by the same extrusion system. CBA contents die temperatures, drawdown ratios (DDR) and wood fibre contents (WF) were varied for optimization of mechanical properties and morphology. Cell morphology and fibre alignment was characterized by a scanning electron microscope (SEM). A new compression molding system was developed to help in quick evaluation of different material formulations. This system forces the materials to flow in one direction to achieve higher net alignment of fibres during sample preparation, which is the case during profile extrusion. Operation parameters were optimized and improvements in WPC properties were observed compared to samples prepared by conventional hot press and profile extrusion. / UOIT

Flax fiber-reinforced plastic composites have attracted increasing interest because of the advantages of flax fibers, such as low density, relatively high toughness, high strength and stiffness, and biodegradability. Thus, oilseed flax fiber derived from flax straw, a renewable resource available in Western Canada, is recognized as a potential replacement for glass fiber in composites. Among plastics, polyethylene is a suitable material for use as a matrix in composites. However, there are not many studies in this area. Therefore, the main goal of this research was to develop flax fiber-polyethylene (PE) biocomposites via injection molding and investigate the effect of material properties and processing parameters on their properties. <p>Alkali, silane, potassium permanganate, sodium chlorite, and acrylic acid treatments were employed to flax fiber to decrease the hydrophilic of fiber and improve the adhesion between the fiber and the matrix. All chemically treated fiber-HDPE biocomposites had higher tensile strength and lower water absorption compared with non-chemically treated ones. Acrylic acid treatment of the fiber resulted in slight increase in its degradation temperature; using this treated fiber resulted in biocomposites with the best performance. Therefore, the morphological, chemical, and thermal properties of acrylic acid treated fiber were also studied. <p>Linear Low Density Polyethylene (LLDPE) and High Density Polyethylene (HDPE) were the main matrices investigated in this research. Showing a high tensile strength and similar water absorption, HDPE was used as the matrix in further research. Flax fiber with 98-99% purity was chosen as reinforcement since the flax shive mixed with the fiber decreased the tensile and flexural properties but increased the water absorption of the biocomposite. <p>Acrylic acid-treated fiber-HDPE biocomposites had been developed through injection molding under different processing conditions. Increasing the fiber content of biocomposite increased its tensile and flexural strengths, especially flexural modulus, but its water absorption capacity also increased. It was possible to improve the mechanical properties of biocomposites and decrease the water absorption by adjusting injection temperature and pressure. Injection temperature had more influence on the quality of the biocomposite than injection pressure. Injection temperature lower than 195°C was recommended to achieve good composite quality. <p>Melts of HDPE and flax fiber-HDPE biocomposites were categorized as power-law fluids. Apparent viscosity, consistency coefficient, and flow behavior index of biocomposites were determined to study their flow behavior. The statistical relationship of these parameters with temperature and fiber content were modeled using the SAS and SPSS softwares. The injection filling time was related to the material rheological properties: biocomposites required longer filling time than pure HDPE. Low injection temperature also resulted in long filling time.<p>The thermal conductivity, thermal diffusivity, and specific heat of biocomposites containing 10, 20, and 30% fiber by mass were determined in the processing temperature range of 170 to 200°C. Fiber content showed a significant influence on the thermal properties of the biocomposites. The predicted minimum cooling time increased with the thickness of the molded material, mold temperature, and injection temperature, but it decreased with the ejection temperature.

Flax fiber-reinforced plastic composites have attracted increasing interest because of the advantages of flax fibers, such as low density, relatively high toughness, high strength and stiffness, and biodegradability. Thus, oilseed flax fiber derived from flax straw, a renewable resource available in Western Canada, is recognized as a potential replacement for glass fiber in composites. Among plastics, polyethylene is a suitable material for use as a matrix in composites. However, there are not many studies in this area. Therefore, the main goal of this research was to develop flax fiber-polyethylene (PE) biocomposites via injection molding and investigate the effect of material properties and processing parameters on their properties. <p>Alkali, silane, potassium permanganate, sodium chlorite, and acrylic acid treatments were employed to flax fiber to decrease the hydrophilic of fiber and improve the adhesion between the fiber and the matrix. All chemically treated fiber-HDPE biocomposites had higher tensile strength and lower water absorption compared with non-chemically treated ones. Acrylic acid treatment of the fiber resulted in slight increase in its degradation temperature; using this treated fiber resulted in biocomposites with the best performance. Therefore, the morphological, chemical, and thermal properties of acrylic acid treated fiber were also studied. <p>Linear Low Density Polyethylene (LLDPE) and High Density Polyethylene (HDPE) were the main matrices investigated in this research. Showing a high tensile strength and similar water absorption, HDPE was used as the matrix in further research. Flax fiber with 98-99% purity was chosen as reinforcement since the flax shive mixed with the fiber decreased the tensile and flexural properties but increased the water absorption of the biocomposite. <p>Acrylic acid-treated fiber-HDPE biocomposites had been developed through injection molding under different processing conditions. Increasing the fiber content of biocomposite increased its tensile and flexural strengths, especially flexural modulus, but its water absorption capacity also increased. It was possible to improve the mechanical properties of biocomposites and decrease the water absorption by adjusting injection temperature and pressure. Injection temperature had more influence on the quality of the biocomposite than injection pressure. Injection temperature lower than 195°C was recommended to achieve good composite quality. <p>Melts of HDPE and flax fiber-HDPE biocomposites were categorized as power-law fluids. Apparent viscosity, consistency coefficient, and flow behavior index of biocomposites were determined to study their flow behavior. The statistical relationship of these parameters with temperature and fiber content were modeled using the SAS and SPSS softwares. The injection filling time was related to the material rheological properties: biocomposites required longer filling time than pure HDPE. Low injection temperature also resulted in long filling time.<p>The thermal conductivity, thermal diffusivity, and specific heat of biocomposites containing 10, 20, and 30% fiber by mass were determined in the processing temperature range of 170 to 200°C. Fiber content showed a significant influence on the thermal properties of the biocomposites. The predicted minimum cooling time increased with the thickness of the molded material, mold temperature, and injection temperature, but it decreased with the ejection temperature.

This thesis explores the analysis and fabrication of plastic hypodermic needles. The hypotheses for this work are that replacing metal hypodermic needles with plastic ones will reduce or eliminate the possibility of the second-hand infections from needle sticks and unsterlized reuse and will be more cost and time efficient to recycle. The most critical structural failure mode for plastic needles is buckling due to their shape (thin walled hollow column). The consideration of buckling is critical to avoid structural failure and to ensure reliability for medical applications. The buckling strength of a cannula is analyzed by analytic (Euler buckling theory) and finite element analysis (FEA) methods. A 22 gage needle model (OD 0.7mm, ID 0.4mm, Length 12.7mm) was analyzed. Euler buckling theory was used to calculate the critical buckling load. Numerical approaches using finite element analyses showed very similar results with analytic results. A skin model was introduced to simulate boundary conditions in the numerical approaches. To verify the results of the analyses, cannulas with the same cross-sectional dimensions were fabricated using a micro injection molding technique. To make the parts hollow, a core assembly of straightened wire was used. Using the tip of a 22 gage needle, cannulas with the inverse shape of an actual hypodermic needle were made. The structural (buckling) characteristics of cannulas were measured by a force-displacement testing machine. When buckling occurred, an arch shape was visible and there was an abrupt change in the load plot. Test results showed the relation between the needles length and the buckling load, which was similar to that predicted by Euler buckling theory. However, test values were 60% of the theoretical or analytical results. Several reasons to explain these discrepancies can be found. The first is that an unexpected bending moment resulted from an eccentric loading due to installation off-center to the center of the testing machine or to the oblique insertion. A cannula that was initially bent during ejection from the mold can add an unexpected bending moment. The quality control of cannulas can be another reason. Bent or misaligned core wires produce eccentric cannulas, and the thinner wall section can buckle or initiate fracture more easily. The last reason may be that Euler buckling theory is not fully valid in short cannula, because the axial stress reaches yield stress before buckling occurs. Inelastic deformation occurs (i.e., the modulus is reduced) during compression in short cannula. The Johnson column formula is introduced to explain this situation. Especially for the nylon nanocomposite material tested, a loss in modulus due to moisture absorption may be another explanation for the discrepancies.

Computer-aided design and simulation software are used in this thesis. AutoCAD is used to create pattern and mask; Pro/E is applied to build 3D model. TracePro software is used to simulate the optical performance. We use software for simulation and analysis. The data from simulation and analysis will be helpful to increase the strike-rate in process. Photolithography process is applied in this thesis for gapless crack polygonal lens array fabrication. In this process, photo resistance, AZ-4620 is spun on the substrate, and expose it after mask alignment, followed by the developing process. The cylinder column with the same size in diameter is formed after this process. Next, apply heat to photo resist. The cylinder structure becomes semi-sphere due to surface tension effect. Then, sputter silver layer on the semi-sphere. The semi-sphere becomes metal mold after nickel electroforming. Nickel alloy core is formed after electroplaing. Then, apply UV cuve resin on the nickel alloy core, and spinning out the extra UV glue. Then, cure it with UV light. Gapless crack polygonal lens array is completed after this series process. The result shows that it can be applied on different optical devices.

Replacing steel and wood with plastic is the developing trend in the modern industry. In many shaping processing methods¡M the injection molding technology is widely used in plastic industry for its good adaptability¡M high producing efficiency and easy-achieve to automation. Injection molding is a very complicated physical process¡M the molding parameters (including temperature¡M pressure¡M time¡M speed and position etc) and environment condition will directly affect the flowing condition of melting plastic and final quality of products¡M so to obtain the best molding parameters is the key to improve the quality of the plastic products. The traditional method of adjusting parameters is try and error¡M which wastes time and materials. And it¡¦s also hard to accumulate and transmit experience¡M so we urgently need to find a new method. By going through a long time of experiment and exploring¡M we found that the DOE (Design of Experiment)¡M which is one of the most important tools of 6 sigma¡M can be applied to improving the molding processing¡M and it will bring us the innovation of injection molding technology. DOE is one of the mathematic methods¡Mwhich bases on Probability theory¡M Statistics and Linear algebra¡M through rationally arrange experiment and correctly analyze the results of experiment¡M to obtain the best parameters. In the processing of exploring¡M we have obtained first-step success in shortening cycles¡M reducing weight of product and improving qualities. For the sake of extending and developing the methods of DOE applied to molding technology in the company and transmitting experience of experts¡M we are going to conclude many DOE cases as a rule¡M establish a database¡M develop an injection molding expert system¡M which will be the effective way to bring cost down¡M improve efficiency and establish a core-competition capability of injection molding technology.

Thesis (PhD--Mechanical Engineering)--University of Auckland, 2009. / " A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering." "Centre for Advanced Composite Materials." Includes bibliographical references.

Thesis (M.S.)--Brigham Young University. Dept. of Chemical Engineering, 2003. / Includes bibliographical references (p. 69-74).

Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, 1999. / Word processed copy. Summary in English. Includes bibliographical references (leaves 95-99). Also available online.

 This research is concerned with the transformation Mould and Die (MD) manufacturing industry from the traditional manufacturing paradigm into service-oriented manufacturing (SOM) in collaboration with leading manufacturers in the sector. It investigates how the new concept of Production Service System (PnSS) can be used and extended to integrate distributed manufacturing-oriented services (MOSs) so that all participants could efficiently and effectively collaborate in response to market opportunities. In the PnSS model, MD manufacturers become more specialized in providing certain types of MD products and components while outsourcing other components or related services as MOSs from MOS providers (MOSPs). The main objective of this research is to develop an information and collaboration platform for PnSS (iPnSS) to utilize MOSs and support the implementation of PnSS strategy for MD industry. The proposed iPnSS is developed based on the SOA (Service-oriented Architecture) paradigm, which aims to encapsulate MOSs as Software as a Service so that MOSs can be advertised, searched, and utilized by stakeholders in PnSS. Several core MOSs have been developed as the core components of iPnSS to meet the urgent requirements of participants in new business model, including Ontology-based Dynamic Alliance Service (ODAS) for forming PnSS alliance, Real-time Order Progress Kanban Service (RT-OPKS) for collaborative project tracking and coordinating, and Hybrid Flow Shop Assembly Scheduling Service (HFS-ASS) for production planning and scheduling which is specified for MD production. The research makes several key contributions. First, this research investigates the characteristics and challenges of MD industry, and develops the PnSS business model to transform the traditional manufacturing into service-oriented manufacturing for MD industry. An information and collaboration platform called iPnSS is developed to provide related IT solutions for integrating distributed MOSs to facilitate the practical usage of PnSS. Second, Ontology-based Dynamic Alliance Service is developed to enable participants to form alliance and take advantage of SOM. This service provides a systematic and integrated supplier selection approach in PnSS, being responsible for the major stages in the life cycle of a service-enabled manufacturing process, including service provision and consumption as well as service evaluation and organization respectively. Third, Real-time Order Progress Kanban Service with the support of Radio Frequency Identification (RFID) technology is developed to support the efficient knowledge feedback for shop floor visibility and traceability. This service provides a set of mechanisms to monitor, evaluate and coordinate the manufacturing execution during the process of collaborative manufacturing after the formation of alliance. Finally, Hybrid Flow Shop Assembly Scheduling Service is developed to deal with scheduling problem for manufacturing one-of-a-kind products, which is based on real-life study with MD industrial collaborators. For each order in MD manufacturing is assembled after the required components have been produced, the service firstly considers the production simultaneity of components of the same product for final assembly. The service automatically generates scheduling results for PnSS user. / published_or_final_version / Industrial and Manufacturing Systems Engineering / Doctoral / Doctor of Philosophy