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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Evaluation of fiber-matrix interfacial shear strength in fiber reinforced plastics

Sabat, Philippe Jacques January 1985 (has links)
The role of the interphase in fiberglass reinforced composites was studied by a combination of theoretical analysis, mechanical tests, and several high-resolution analytical techniques. The interphase was varied in composition by using epoxy and polyester matrix polymers with and without added coupling agents, as well as four fiber surface modifications. Different coupling agents on the fibers were shown to change the fiber tensile strength markedly. Filament wound unidirectional composites were tested in short beam "shear." Corresponding samples were fabricated by embedding one to seven fibers in the center of polymer dogbone specimens that were tested in tension to determine critical fiber lengths. Those values were used in a new theoretical treatment (that combines stress gradient shear-lag theory with Weibull statistics) to evaluate "interfacial shear strengths". The fact that results did not correlate with the short beam data was examined in detail via a combination of polarized light microscopy, electron microscopy (SEM) and spectroscopy (XPS or ESCA) and mass spectroscopy (SIMS). When the single fiber specimens were unloaded, a residual birefringent zone was measured and correlated with composite properties, as well as with SIMS and SEM analysis that identified changes in the locus of interphase failure. Variations in the interphase had dramatic effects upon composite properties, but it appears ·that there may be an optimum level of fiber-matrix adhesion depending upon the properties of both fiber and matrix. Fiber-fiber interactions were elucidated by combining tensile tests on multiple fiber dogbone specimens with high-resolution analytical techniques. In general, this work exemplifies a multidisciplinary approach that promises to help understand and characterize the structure and properties of the fiber-matrix interphase, and to optimize the properties of composite materials. / Master of Science

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