This chapter examines the following concepts: wet-out of thermoplastic composite materials, processing short-fiber thermoplastic composites, thermoplastic composites molding by traditional thermoset processes, and thermoplastic composites molding by unique processes. Molding of thermoplastic composites is strongly dependent on the length of the reinforcement. If the fibers are short (whiskers), then the thermoplastic composite can be processed much like a traditional non-reinforced thermoplastic. If the fibers are long, the thermoplastic composite, with some important adjustments, can be processed like a standard thermoset composite. However, the unique properties of thermoplastics, especially high-performance thermoplastics, permit some unique methods of processing that hold great promise for highly efficient and low-cost molding of thermoplastic composites. Some of these have already been realized. As the various manufacturing methods for thermoplastic composites are examined, some advantages and disadvantages of these materials versus thermoset composites should be kept in mind. The most common applications for reinforced thermoplastics are relatively small parts where fast molding cycles are critical and the desired properties of the part can be met by short-fiber composites. As the parts become larger, the ability to quickly mold them (usually by injection molding) decreases and the advantages of short-fiber-reinforced thermoplastics diminish.
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