Date of Award

8-1-2014

Degree Type

Thesis

Degree Name

Master of Science

Department

Engineering

First Advisor

Rani El Hajjar

Committee Members

Adeeb Rahman, Benjamin C. Church

Keywords

Carbon Fiber, Co-Mingled Fibers, Composite, PEI, Polyetherimide, Thermoplastic

Abstract

Continuous fiber-reinforced thermoplastics (CFRT) have the potential for being a mass-produced material for high-performance applications. The primary challenge of using CFRT is achieving fiber wet-out due to the high viscosity of thermoplastics. This results in higher temperatures and pressures required for processing the composites. Co-mingling thermoplastic fibers with a reinforcing fiber, potentially, can enable better wetting by reducing the distance the matrix needs to flow. This could result in shorter cycle times and better consolidation at lower temperatures and pressures. In this study, a polyetherimide (PEI) fiber was comingled with carbon fibers (CF). The resultant fibers were woven into fabrics and processed through a compression-molding technique to form laminates. Control specimens were also fabricated using films of PEI layered between plies of woven carbon-fiber materials. The manufactured CFRT panels were evaluated using ultrasonic C-scans (scans in two spatial dimensions) and then characterized for mechanical properties. The specimens produced using the co-mingled fibers had the cycle time reduced significantly compared to the film CFRT, although the results from the mechanical property evaluations were mixed. The behaviors in the co-mingled laminates can be attributed to the resin- and void-content distribution and the fiber-bundle orientations in the cured composite.

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