Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 43 for “"thermoplastic polymers"”.
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Migration of additives from thermoplastic polymers
… for understanding the solubility of additives in polymers The volubility of stabilisers from low density polyethylene films showed that of an additive from a polymer can be expressed in terms of a first-order kinetic equation. In addition the rate of loss of stabilisers was discussed in relation …
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Ultrasonic Welding of Glassy Thermoplastic Polymers
Ultrasonic welding of thermoplastic polymers has been practiced industrially for many years without being fully understood. This study includes an analysis of the energy dissipation mechanisms responsible for the formation of ultrasonic welds in PMMA including viscoelastic loss and by plastic …
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Solid-state processing of thermoplastic polymers
… our understanding of compaction and sintering of polymers. It was demonstrated that mechanical properties (yield strength, modulus) and physical characteristics (degree of physical aging, glass transition temperature, presence of crystallinity) of the particles, and thus, powder processing, …
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Method for Photopolymerization 3D Printing of Recyclable Thermoplastic Polymers
… polymerization, yield non-recyclable thermoset polymers, which pose sustainability issues at scale. This thesis studies a method for photopolymerization 3D printing of the common polymers polyacrylonitrile (PAN) and polymethyl methacrylate (PMMA) to address the growing demand for low-waste …
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Carbon fiber surface treatments for improved adhesion to thermoplastic polymers
… fiber. The work of adhesion of carbon fibers to thermoplastic resins was calculated using the geometric mean relationship. A correlation was observed between the dispersive component of the work of adhesion and the interfacial adhesion.
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Crystallization behavior and structure property behavior of selected thermoplastic polymers
… PEEK-PSX, multi block copolymers and their ketimine precursors, PEEKt-PSX, were investigated. A dran1atic dependence on thermal history prior to crystallization was observed in both block copolymer systems. Block copolyn1crs crystallized from the glassy state obtained a …
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Investigations of Structure–Property Relationships in Semicrystalline Thermoplastic Polymers: Blown Polyethylene Films and Polyacrylonitrile Copolymers
… acrylate) materials. Five polymers were studied with methyl acrylate (MA) content varying between 0 and 15 mol%. The MA decreased both the glass transition and melting temperatures. Melting point depression was sufficient in the two highest MA content copolymers to allow for …
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Structure-property relations in liquid crystalline and thermoplastic polymers: Crystal structure and morphology of liquid crystalline polyethers and the interaction of creep and physical aging in a semicrystalline thermoplastic matrix composite
The crystal structure and morphology of a family of aromatic-aliphatic azomethine polyethers (where the aliphatic unit was composed of CH$\sb2$ units ranging in length from n = 1, 4, 7, 8, 9 and 10) has been examined primarily by Electron microscopy(EM) and Electron diffraction(ED).
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High performance thermoplastic matrix composite processing: dry powder prepregging, plasma treatment, consolidation/crystallization analysis
… A great deal of this interest lies in the use of thermoplastic polymers as the composite matrix. Thermoplastics offer the potential of improved mechanical performance, greater solvent resistance, better impact tolerance, as well as cost saving processing attributes such as infinite shelf life, the …
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The fabrication of carbon-fiber composites by aqueous suspension prepregging with larc-tpi and peek
A novel method of impregnation was used to make thermoplastic prepregs with aqueous suspension of polymer powder and AS-4 carbon fibers. The prepregging, consolidation, and laminate evaluation procedures are described in this report. The need and importance of a dispersing and binding agent and its …
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Investigation of interfacial bonding in banana fiber-reinforced composites : ascribing global economic value to unique renewable resources in developing countries.
… poor interfacial bonding with the majority of thermoplastic polymers. As a result, the benefits of the increased composite stiffness and strength are greatly reduced. In order to increase this interfacial bonding, a variety of surface and chemical treatments have been explored, including fiber …
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Mechanics of large-strain deformation of particle-modified polymers
Over the past several decades, engineering polymers have become increasingly prevalent in the manufacture of virtually all types of products. Polymers are substantially less dense than metals, easy to machine, and readily formed into quite complex geometries. The properties of polymers may be …
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Microfluidic Platform for Vascularized Tissue Models
… of the tissue culture devices arc ma.de of thermoplastic polymers, and their design is translatable to injection molding for future production at scale. The design and manufacturing methods for the platform and individual device features are discussed. Two major biological experiments are …
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The effects of thin polymeric surface films on fretting corrosion
… funded by the Army Research Office. Four thermoplastic polymers were tested for their effectiveness. Two other independent variables were also tested: plate hardness and plate roughness. A ball-on-plate device was built to approximate point sliding at the fretting corrosion interface. The …
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A thermo-mechanical finite deformation theory of plasticity for amorphous polymers : application to micro-hot-embossing of poly(methyl methacrylate)
Amorphous thermoplastic polymers are important engineering materials; however, their nonlinear, strongly temperature- and rate-dependent elastic-visco-plastic behavior has, until now, not been very well understood. The behavior has previously been modeled with mixed success by existing constitutive …
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High throughput extrusion additive manufacturing – rate limits and system design
… of length scales and with a wide variety of thermoplastic polymers and composites. As such, FFF is increasingly used in prototyping, low volume production, and tooling/fixture applications. One of the drawbacks to FFF is its low build rate, which is limited by the fundamentally serial nature …
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A Study of Processing-Structure-Property Correlations in Novel Inorganic Phosphate Glass/Polyamide 66 Hybrid Materials with Enhanced Benefits
… plastic materials. Recent study found that polar thermoplastic polymers seem to have a good interaction with the Pglass. In this study, the Pglass was introduced into a commodity thermoplastic polymer matrix, polyamide 66 (PA66), using a conventional melt-mixing process. Torque reduction and …
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Dielectric studies of novel polymeric systems
… to enhance understanding of molecular motions of polymers and. how they are influenced by' structure. The primary characterization method was dielectric spectroscopy which utilizes an AC electric field as the stress field. A variety of new, well controlled polymeric systems were studied. The first …
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Synthesis and Characterization of Phosphine Oxide Containing Monomers and of the Flame Resistant Polymers Prepared Therefrom
… fire testing methodologies showed that the new polymers containing phosphine oxide units were fire resistant while maintaining the desirable physical characteristics of carefully selected control systems. In addition, suitable curing schedules for epoxy networks were determined by using …
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Development of novel optical sensors
… incorporation of such intelligent pigments into thermoplastic polymers to create a range of flexible plastic indicators is described. The characterisation (e.g. response and recovery times, CO₂ sensitivity and effect of humidity and temperature on such sensitivity) of the indicator films revealed …
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