Fiber-reinforced thermoplastic composite components with low weight, so-called light-weight components for transport and mobility, lead to significant CO2 savings. Despite established production technologies and weight savings, further progress in lightweight construction is increasingly difficult because the sustainability of these products is cur-rently not given due to the unresolved recycling problem, although the regulations re-quire, among other things, 85 % recycling of an end-of-life vehicle. Despite near-net-shape production and advanced automation, the production of polypropylene (PP) organic sheets or PP-UD tapes for lightweight construction generates up to 40 % waste, only some of which has so far been recycled. Complicated component geometries also require sub-sequent trimming of the organic sheet or UD tape reinforced parts after forming. The re-cycling of secondary composites made from thermoplastic organic sheets or UD tapes has hardly been researched, which results in obstacles to the use of recyclates, especially in the automotive industry due to high quality requirements and tight specifications. Recy-clates also have a "heat history" that usually makes reprocessing difficult. Fiber-reinforced composite components therefore end up as post-consumer (P-C) waste for incineration. Consequently, the development of innovative recycling concepts and a new process technology with a closed product cycle are necessary for a broad market application.
The aim of this project is to further develop injection molding compounding (SGC) as an innovative process technology for the closed-loop and energy-efficient recycling of glass fibre composite waste (LightCycle process). In addition, polypropylene reclaims (rPP) from P-C and post-industrial(P-I) sources are used as matrix material and extensively characterized. By ideally completely saving new material and reducing energy require-ments through the one-step LightCycle process, existing resources are optimally used, massive CO2 savings are made, and material cycles are closed through upcycling into high-quality technical products.
For the upcycling of these materials, (1) a new injection molding compounding process in the form of a LightCycle pilot plant is being developed, (2) a formulation metho-dology for thermo-oxidative stabilization and glass fiber reinforcement from recycled material is be-ing worked out, (3) a new inline measurement technique for continuous detection of glass fiber content and melt quality is being developed, and (4) the cause-effect relationships between relevant process parameters and the mechanical properties of the TC compo-nents are being determined with regard to an AI-based quality control system to be devel-oped in a follow-up project. These four developments are important elements of a robust process control with high material and energy efficiency. Finally, the compounded glass fiber reinforced regranulates will be used (5) in a case study for the production of a simple thermoplastic demonstrator component with PP-UD tape reinforcement and GF-rPP overmolding to prove the applicability of the process. Life cycle assessment (6) is used to compare the improved environmental footprint for the single-stage process (LightCycle pilot plant) versus the two-stage for the production of rPP lightweight injection molded parts.
By increasing the process efficiency of the single-stage process and by substituting prima-ry resources with recycled materials the project consortium from industry
(ENGEL Austria GmbH, Leistritz Extrusionstechnik GmbH and Gabriel-Chemie Gesell-schaft m.b.H.) and science (Montanuniversität Leoben – Department for Polymer Engi-neering and Science and Johannes Kepler Universität Linz – LIT Factory) contributes to the circular economy and positive climate impact.