Design and development of thermoplastic composite manufacturing processes based on electrostatic powder spray impregnation

This research encompasses the design and development of a versatile thermoplastic composite manufacturing process. This process was specifically designed to include all the stages of a complete composite manufacturing process, from the initial combination of the resin and fiber materials to the final part consolidation. A detailed apparatus was designed to spread continuous fibers, coat them with electrostatically charged polymer powder particles, and consolidate the resulting materials into net-shape composites ranging from high fiber content aerospace grade components to fiber-reinforced thermoplastic pellets for injection molding. An experimental evaluation of the fiber coating process showed that electrostatic charging of the polymer powders caused a dramatic increase in the deposition rate onto glass fibers. The amount of resin deposited was controllable by varying the powder mass flowrate. A detailed study of fiber spreading showed how the average fiber spreading width varied as the line velocity, spreading airflow, or fiber tension changed. Consolidation processes were concurrently designed to capitalize on the advantages of electrostatic powder impregnation. An in-situ filament winder was designed to manufacture cylindrical components from the resulting thermoplastic composite material. Long fiber thermoplastic injection molding pellets were produced at both speeds and resin impregnation levels rivaling fully developed commercial melt processes