ABSTRACT
Compression molding is one of the oldest techniques for processing polymers, though it has not received a great deal of study on the fundamental level. For many years the standard technique for molding phenolics and similar thermosets, it has to some extent been replaced by thermoset injection molding. By comparison, injection molding offers advantages in materials handling and ease of automation. However, compression molding retains a distinct advantage when processing reinforced polymers. Compression molding flows involve modest amounts of deformation, and there are no regions of very high stress, such as at the gate of an injection mold. Consequently, reinforcing fibers are not damaged by the flow during mold filling as often happens in injection molding. Thus, higher concentrations of reinforcing fibers and longer fibers can be included in compression-molded materials. Recent interest in polymer matrix composites for strong, lightweight structures has renewed interest in compression molding. Many developments in compression molding are concerned, either directly or indirectly, with the processing of composite materials.
