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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

Processing of composite fibers based on polypropylene and a thermotropic liquid crystalline polymer

Robertson, Christopher G. 17 January 2009 (has links)
Isotactic polypropylene (PP) was reinforced with Vectra B950 (VB), a thermotropic liquid crystalline polymer (TLCP), in two novel fiber spinning processes. In one process, a single VB melt stream was surrounded by a sheath of PP in a manner comparable to a wire coating process just prior to melt spinning to generate fibers possessing a sheath-core structure. The other process involved the distribution of continuous VB melt streams within a separately plasticated PP melt to form a composite melt which was drawn to create matrix-fibril fibers consisting of a PP matrix in situ reinforced with VB fibrils. Both processes allow polymers with non-overlapping processing temperatures to be combined and melt spun to form composite fibers. The effect of fiber draw ratio on the tensile mechanical properties was assessed for composite fibers reinforced with 50 wt.% (39 vol.%) VB. Numerical simulations of the non-isothermal fiber drawing processes and an investigation of fiber morphology were undertaken in order to explain the mechanical properties. The matrix-fibril (in situ) reinforced fibers were woven into fabric preforms. The preforms, pre-wetted with PP, were used to fabricate orthotropic composites, and the mechanical performance and formability of these composites was evaluated. / Master of Science

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