Thesis (Ph. D.)--University of Washington, 1992. / Vita. Includes bibliographical references (leaves [267]-272).

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xi, 87 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 86-87).

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Suresh G. Advani, Dept. of Mechanical Engineering. Includes bibliographical references.

During the fabrication of a filament-wound composite case, which includes the winding and cure stages, the tension in the fiber can change significantly. If the level of fiber tension decreases excessively during fabrication, fiber slippage and clumping can occur. The resulting resin rich areas can significantly decrease the strength of the composite case. The objectives of the present investigation were 1) to measure the change in fiber tension during the winding and cure of a composite case wound with prepreg material, and 2) to calculate the change in tension during cure using a simulation computer program. Of particular interest was the loss of fiber tension due to resin flow (RFTL). A total of twenty-four tension loss experiments were performed using Amoco’s Thornel T40 fiber and T40/1908 prepreg materials. The parameters which were varied in the experiments were spool tension, oven heating rate, and the number of composite layers. Some of the experiments were designed to isolate and measure RFTL by comparing the changes in tension of winds of dry fiber and prepreg material. This method was not successful due to a similarity in prepreg and dry fiber tension loss characteristics. Low spool tensions were found to result in more tension loss due to resin flow (RFTL). RFTL was also greater for an increased number of layers, but was not affected by oven heating rate. During winding, significant tension loss occurred, probably due to deformation of the prepreg tow at room temperature. The change in fiber tension during cure was calculated using an existing cure simulation code (FWCURE) which was modified in this work to include the contribution to fiber tension made by the thermal expansion of the mandrel during cure. The revised code is called FWEXPAND. By adjusting the permeability model in FWEXPAND, the fiber tension during the cure of a single layer wind was accurately calculated. The predicted total RFTL of two multi-layer winds agreed reasonably well with the measured RFTL, but the rate of tension loss was overpredicted. Complete RFTL and full compaction occurred during the first ramp of the cure cycle in all of the experiments. / Master of Science

Abstract not available

For thesis abstract select View Thesis Title, Contents and Abstract

Natural fibers are gaining popularity as reinforcement materials for thermoset resins over the last two decades. Natural fibers are inexpensive, abundant, renewable and environmentally friendly. Kenaf fibers are one of the natural fibers that can potentially be used for reinforcing unsaturated polyester (UPE). As a polymer matrix, UPE enjoys a 40% market share of all the thermoset composites. This widespread application is due to many favorable characteristics including low cost, ease of cure at room temperature, ease of molding, a good balance of mechanical, electrical and chemical properties. One of the barriers for the full utilization of the kenaf fiber reinforced UPE composites, however, is the poor interfacial adhesion between the natural fibers and the UPE resins. The good interfacial adhesion between kenaf fibers and UPE matrix is essential for generating the desired properties of kenaf-UPE composites for most of the end applications. Use of a coupling agent is one of the most effective ways of improving the interfacial adhesion. In this study, six novel effective coupling agents were developed and investigated for kenaf-UPE composites: DIH-HEA, MFA, NMA, AESO-DIH, AESO-MDI, and AESO-PMDI. All the coupling agents were able to improve the interfacial adhesion between kanaf and UPE resins. The coupling agents were found to significantly enhance the flexural properties and water resistance of the kenaf-UPE composites. Fourier transform infrared spectroscopy (FTIR) confirmed all the coupling agents were covalently bonded onto kenaf fibers. Scanning electron microscopy (SEM) images of the composites revealed the improved interfacial adhesion between kanaf fibers and UPE resins. / Graduation date: 2013

Thesis (M.Eng.). / Written for the Dept. of Mechanical Engineering. Title from title page of PDF (viewed 2008/01/14). Includes bibliographical references.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 123-127). Also available via the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 183-191). Available also in a digital version from Dissertation Abstracts.