International Polymer Processing, Vol.8, No.4, 319-327, 1993
RIM-PULTRUDED PREPREG FOR THE INJECTION-MOLDING OF LONG-FIBER EPOXY COMPOSITES
A long-fiber injection molded phenoxy composite has been developed by using a new processing technique that combines reaction injection molding (RIM) and pultrusion to produce a prepreg pellet. RIM-pultrusion uses a reaction injection system instead of the resin bath typically used in pultrusion. The resin system and process developments are described. The fiber damage during injection molding is minimized by using the RIM-pultruded pellet as prepreg. The resulting long-fiber carbon fiber composite has an average volume aspect ratio that is an order of magnitude higher compared to typical short-fiber injection molding. The fiber length distribution (FLD) is measured for both glass and carbon composites. The extent of bundling has been determined from the moment ratio. The extent of reaction of the diepoxide during processing is measured using Fourier transform infrared spectroscopy (FT-IR). The pultrusion line speed and temperature are determined for secondary processing, namely injection molding, from the epoxide conversion. Also, dynamic mechanical analysis has been performed on the resin, prepreg, and injection molded sample to study the mechanical and thermal properties. Scanning electron microscopy is employed to examine fiber-matrix adhesion, void content, bundling, and fiber pull-out.