Thesis (M.S. in civil engineering)--Washington State University, December 2008. / Title from PDF title page (viewed on Mar. 10, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2010. / Title from PDF t.p. (viewed June 30, 2010). Additional advisors: R. Michael Banish, Derrick R. Dean, Nasim Uddin, Uday K. Vaidya. Includes bibliographical references (p. 197-202).

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Thesis (M.S.)--Cleveland State University, 2007 / Abstract. Title from PDF t.p. (viewed on May 8, 2008). Includes bibliographical references (p. 81-84). Available online via the OhioLINK ETD Center. Also available in print.

Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains xiv, 185 p. : ill. Includes abstract. Includes bibliographical references (p. 158-167).

The mechanical properties of particulate filled polymers are influenced significantly by interfacial interactions. The adhesion between the polymer and the filler depends on the area of the interface and the strength of the interaction. The former is related to specific area of the filler while the strength of the interaction can be modified by surface treatment. This study is focused on comparing the reinforcing ability of muscovite and phlogopite with and without surface treatment. Muscovite and phlogopite are two common forms of mica. Mechanical properties such as Young's modulus, tensile strength, elongation and impact strength were used to compare the reinforcing ability of muscovite and phlogopite in EVA composites. The Young's modulus of the surface treated and non-surface treated composites increased with an increase in filler loading. Composites reinforced with muscovite had similar moduli compared to composites reinforced with phlogopite. The tensile strength of phlogopite reinforced composites increased with an increase in filler content while that of muscovite reinforced composites remained constant. Surface modification by both silane and stearic acid reduced the tensile strength of phlogopite reinforced composites. The tensile strength of stearic acid treated muscovite reinforced composites improved but not to the same extent as the silane treated composites. Both muscovite and phlogopite lead to a lowering of the impact strength at high filler loadings while the tensile impact strength of both muscovite and phlogopite reinforced composites improved when using silane and stearic acid. In non-surface treated systems, muscovite reinforced composites showed an initial increase in elongation while the elongation of phlogopite reinforced composites decreased with an increase in filler loading. Elongation at maximum load values, however, increased at low filler loadings, when using stearic acid. It can be concluded that stearic acid is not an effective coupling agent for mica/EVA composites and that the use of silane for phlogopite reinforced composites does not offer any improvement in mechanical properties. / Dissertation (MSc (Chemical Technology))--University of Pretoria, 2006. / Chemical Engineering / unrestricted

A cheaper access to space is needed in current times and new technologies need to be developed to reduce the cost of space access to increase productivity. This thesis presents a study on carbon fiber reinforced polymer (CFRP) composites which is an enabling technology for cost reduction in space vehicles. A literature review of the behavior of CFRP composite has been conducted and it was found that the currently used IM7/977 carbon fiber reinforced epoxy composites do not microcrack at a lower number of thermal cycles. Nano-composites and Thermoplastic matrix composites have been found as two promising alternatives for cryogenic applications. With the use of nano sized inclusions in currently used epoxy resins, coefficient of thermal expansion can be reduced while increase in strength and fracture toughness can be achieved. Some thermoplastics were found to have non-linear stress-strain relationships with signs of ductility even at 4.2K. Both of these resin systems show promise in reducing microcracking at cryogenic temperatures.

The quest for developing high performance materials, originally responsible for the birth and growth of the composites industry, is now responsible for the drive to produce composites which outperform those used today. 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 ability to be recycled, short processing time and repairability. Unfortunately, these advantages come at the expense of a very high melt viscosity which makes the prepregging process, where the fiber and polymer are combined, very difficult. To overcome this and associated difficulties a detailed analysis of thermoplastic matrix composite processing is developed. The primary area of focus involves the development of an electrostatic dry polymer powder prepregging facility. This unit is capable of the production of high quality towpreg from thermoplastic polymers and reinforcing fibers. Two approaches, statistical and stochastic, were employed to model the process of polymer deposition on the fibers in the prepregging process. These models are used to optimize the production of towpreg. A modification of the prepregging facility allows for the production of towpreg from very small (15 g) samples of polymer. This is extremely useful for analysis and performance verification of state of the art polymer systems. / Ph. D.

Fabrication of high-quality composites from thennoplastic prepregs requires careful selection of the processing cycles so that intimate contact at the ply interfaces is achieved resulting in the formation of strong interply bonds and the process-induced residual stress is minimized to ensure superior mechanical performance. The void formation and the consolidation mechanism were studied experimentally. A refined model was developed to relate the processing parameters of pressure, temperature and time to the interply intimate contact of thermoplastic composites. The model was developed by integrating a prepreg surface topology characterization with a resin flow analysis. Both unidirectional and cross-ply lay-ups were modeled. Two-ply unidirectional laminae fabricated from graphite-polysulfone and graphite-PEEK prepregs and [0/90/0]_T laminates were consolidated using different processing cycles. Optical microscopy and scanning acoustic microscopy were used to obtain the degree of intimate contact data. Agreement between the measured and calculated degree of intimate contact was good. A finite element model was developed to analyze residual stresses in thermoplastic composites by combining a plane-strain elasticity analysis and a temperature-dependent matrix properties. The residual stress model takes into account the mismatch of the thermal expansion coefficients and the crystallization shrinkage of the matrix. [O₁₀/90₆]_T graphite-PEEK laminates were manufactured at different cooling rates to verify the model. The induced residual thermal defonnations were measured by a shadow moire system. The model accurately estimated the out-of-plane displacement of the non-symmetrical laminates. / Ph. D.