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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES

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The shear strength of unidirectional glass-epoxy composites was determined experimentally by three standard shear tests. The tests consisted of short beam interlaminar shear tests, saw-cut shear tests, and torsion tests on circumferentially wound cylinders. Test results show that the short beam interlaminar shear tests and the torsion tests of circumferentially wound cylinders give approximately the same maximum shear stress. Test results also showed that the saw-cut shear test is not a good interlaminar shear test because of stress concentrations at the base of the saw cuts and high tearing stresses normal to the plane of shear. The shear strength determined by the beam and torsion tests is approximately 10 ksi, whereas the average shear strength for the saw-cut specimens is approximately 2.5 ksi. / Master of Science

An experimental investigation was made to determine the role of gravitational and surface tension forces in the migration of liquid water through fiberglass insulation materials. Straightforward experimental procedures were devised to effectively isolate and quantify flow parameters considered important in describing the flow mechanisms involved. The study was conducted to supplement an earlier investigation into the thermal performance of wetted insulation materials. Darcy's Law was found to apply for the regime of flow encountered in which liquid water flows under the force of its own weight in horizontal rooftop insulation. Experimental determination of the constant of proportionality in Darcy's Law, the hydraulic conductivity, is all that is needed to describe the migration of liquid water in saturated fiberglass insulation. Capillary forces, originally thought to play a significant role in the movement of liquid water through fiberglass insulation, were found to be negligible. Capillary rise up a column of insulation measured no higher than 13 mm. / M.S.

The use of fiber-reinforced polymer composites formed via injection molding is of increasing interest due to their superior mechanical properties as compared to those of the polymer matrix alone. These mechanical properties, however, are strongly dependent on the fiber length and orientation distributions within a molded part. As such, there is a need to understand and model the orientation evolution of chopped fibers in flow in order to accurately simulate the final fiber orientation distribution within injection molded parts. As a result of this, accurate and reliable experimental measurement of fiber orientation is needed. Within this research, the application and validity of the Method of Ellipses for determining the orientation of long, semi-flexible glass fibers within injection molded composites has been investigated. A fiber suspension with an average length of approximately 3.9 mm was the focus of this study and assumed to be representative of commercial distributions. A novel method to quantify fiber curvature was developed and utilized to show that flexibility in center-gated disc and the end-gated plaque samples was minimal on average for the selected fiber length distribution. Thus, it was determined that the Method of Ellipses was applicable when utilized to obtain reliable orientation data for the selected long glass fiber suspension and within the chosen geometries that exhibit 1-, 2-, and 3-dimensional velocity fields. However, a modified image analysis width was found to be necessary in regions of highly aligned fibers, due to the increase in ellipse size and the need to reduce the number of partial objects and thus minimize error. This allowed for a direct comparison of the experimental orientation behavior of short and long glass fibers within the center-gated disc and the end-gated plaque, as well as the effect of the orientation distributions on the global modulus of the part. / Ph. D.

The present study was initiated to evaluate the pulmonary inflammatory and fibrotic responses induced by single and repeated exposures to glass fibers. Single and repeated intratracheal injections of glass fibers induced an acute inflammatory response which progressed to a chronic inflammatory and fibrotic response. Mice exposed to glass fibers in single or repeated doses demonstrated elevated numbers of eosinophils, neutrophils and macrophages and increases in cell-free protein in lung lavage fluid at five days post-exposure. These parameters, in addition to relative lung/body weight ratios and lung tissue hydroxyproline levels, were elevated in comparison to saline control animals at five weeks post-exposure. Although repeated exposures to glass fibers did not potentiate the cellular inflammatory response, they did induce a marked infiltration of eosinophils, a response not observed with either asbestos or silica exposures. These observations suggest that glass fibers may be more toxic to the lungs than previously thought.

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006. / Rectangular components were produced by both standard injection moulding and by a process called Lomolding. Both moulding grade polypropylene homopolymer and glass-filled polypropylene were used. The effect of processing parameters on material properties, as measured by tensile and impact strength, and warpage were determined for both injection moulding and lomolding, for both unfilled and glass-filled polypropylene materials. Sampling of the components allowed for critical evaluation of processing parameters’ effect on material properties at points close to and distant from the injection point, as well as in the direction of materials flow and transverse to material flow. Glass-filled components were also evaluated in terms of glass fibre length and fibre distribution (post-injection). Overall conclusions could be drawn with respect to the 2 different processes and the materials used. It was seen, inter alia, that the specimen orientation had no effect on the mechanical properties when using unfilled polypropylene, but that the orientation of the glass fibres in the testing direction resulted in an increase in the tensile strength and the impact strength for the injection moulded samples. Similar results were seen for lomolded samples, except that the fibre orientation effects were different. In the same vein, other notable differences could be observed for samples produced by lomolding and injection molding. Fibre length and distributions obtained by polymer burn-off experiments served to help explain differences in properties of glass-filled products produced by the two processes.

Wastewater effluent produced in the fiberglass manufacturing industry contains a significant amount of total suspended solids. Environmental regulations require pretreatment of effluent before it is discharged to the municipal wastewater treatment plant. Chemical precipitation by coagulation and flocculation is the method of pretreatment used at the Vetrotex CertainTeed Corporation (VCT). A treatability study was conducted to determine conditions at which the VCT Wastewater Pretreatment Plant could operate to consistently achieve a total suspended solids concentration ≤ 200-mg/L. Jar tests varied pH, polymer dosage, and ferric sulfate dosage. Total suspended solids and turbidity were measured to evaluate treatment performance. The data were used to determine an optimum set of conditions under project guidelines. Of twelve polymers screened, BPL 594 was selected as the most effective polymer. For cost efficiency in the wastewater pretreatment operation, recommendations suggested that treatment chemical injection be electronically controlled according to turbidity of the treated effluent.