The Effect of Recyclate Geometry on the Properties of Recycled Flake Reinforced Thermoset Composites

Abstract

The need to develop recycling solutions for carbon fiber reinforced plastic (CFRP) composites has been well established. However, recycled composites remain inferior to composites fabricated with virgin fibers for several reasons. Realistically, recycled composites can be expected to achieve comparable performance to sheet molding compounds fabricated with virgin fibers if fiber volume fractions can be improved without significantly reducing fiber length. One possible way to achieve this is to fabricate laminates with flakes of cured CFRP. The goal of this research was to investigate the effect of flake geometry on the properties of recycled flake reinforced composites, and to evaluate whether fabricating recycled laminates with CFRP flakes may become a viable alternative to current CFRP recycling techniques. This was accomplished by fabricating and mechanically testing several composite laminates with either shredded flake or single ply flake reinforcement. The shredded material was provided as-shredded by The Boeing Company, and no further processing of the flakes was done prior to resin infusion. The single ply flakes were cured in individual sheets and cut into flakes of different geometries. This flake system was chosen to simulate cured prepreg scrap or delaminated CFRP recyclate, and to provide a well-controlled material system for studying the effects of flake geometry on the properties of flake reinforced composites. The aspect ratio of the singe ply flakes was varied between 1:1 and 1:4 while either flake area or flake length was held constant. Tensile and flexural properties of the recycled flake-reinforced laminates are presented.