Recycling of composites – A new approach minimizes downgrading

Abstract

Fiber reinforced plastics (FRP) hold considerable potential for the construction and design of light-weight parts. FRP are rapidly gaining in importance in various industrial sectors. Although this group of materials combines high strength and stiffness while simultaneously being lightweight, major difficulties still arise when it comes to high volume production and the return of manufactured parts back into the cycle of materials at the end of their lifecycle. A new approach follows the idea of producing structural parts through the forming and back-injection molding of preforms with a large portion of recycled fibers and recycled matrix, without drastically compromising the mechanical properties. To achieve this, carbon fibers retrieved out of a recycling process are blended with recycled polyamide fibers and spun into a hybrid yarn. Subsequently these yarns are processed into preforms by means of Tailored Fiber Placement. This process allows for a precise fiber positioning in accordance with the load path. Additionally, back-injection molding allows functional integration into the parts, aiming for weight reduction and lowering installation effort. Recycled carbon fibers and recycled matrix granules are also utilized for the back-injection molding process using an Injection Moulding Compounder to investigate their influence on mechanical properties of the parts.