Single-walled carbon nanotubes are high strength materials with nano-sized dimensions, which make them attractive as reinforcing materials for polymer matrices. Their nano-sized dimensions however make them difficult to manipulate for macroscopic applications. This thesis focuses on manufacturing and studying nanotube continuous fibers as a means of manipulating these stronger reinforcing materials in thermoplastic polymer matrices to increase the mechanical properties of the composite generated. The thermoplastic polymers used in this thesis are polypropylene and nylon 6,6. This thesis demonstrates the effects of alignment, new chemical functionalizations and increasing weight percentages of the single-walled carbon nanotubes in the nanotube continuous fiber systems. The functionalizations studies include the use of fluorinated single-walled nanotubes, and an attempt to use benzoyl peroxide to initiate covalent bonding of single-walled nanotubes to the polymer in the processing stage of the polypropylene composite systems. (Abstract shortened by UMI.)