Fundamental investigation of potentially recyclable intrinsic polymer fiber-reinforced plastics for local component strengthening by 3D printing using fused filament fabrication FFF

• Applicant: Professor Dr.-Ing. Alois K. Schlarb
• Subject Area: Plastics Engineering
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 497642170

For many applications, the structural properties of neat plastics are insufficient. To improve these properties, polymers are therefore classically reinforced with fibers. However, these usually also result in a higher density and also limit the potential for mechanical recycling, since the reinforcing effect depends on the fiber length and these are inevitably shortened during mechanical recycling in screw machines. This is where microfibrillar composites (MFCs) come in. They are manufactured according to an idea by M. Evstatiev and S. Fakirov (Polymer 1992, 33, 877) and combine the load-bearing advantages of the fiber shape with the low density of plastics. In previous work, it became clear that the reinforcing effect of polymeric fibers in molded part production by injection molding cannot fully exploit since this process generates randomized orientation of the fibers in the volume.The fundamental idea of the present project proposal is to better exploit the advantages of MFC using Fused Filament Fabrication (FFF) with a view to planar 3D contoured structures. Preliminary investigations demonstrates that significant increases in stiffness and strength are possible with MFC and that a multiple pass through a screw machine can be tolerated without losses in the mechanical properties, i.e. mechanical recyclability is potentially available.In the project, the potentials of the FFF/MFC combination are to be systematically and resiliently researched. The overall goal of the proposed project is to open a pathway to high performance and recyclable products as a complement to conventional discontinuous long fiber reinforced plastics by linking MFC and FFF and developing a deep understanding of the relationships between process, morphology and mechanical properties. Specifically, the objectives are:(1) to specifically exploit the orthotropy properties of directional discontinuous long fiber polymer reinforcement in plastic components,(2) to investigate and evaluate the effect of the printing parameter on the resulting component properties in a simulation-based and morphology-related manner,(3) to investigate the influence of compatibilizers on fibril formation and fibril-matrix adhesion, and(4) to evaluate the suitability of the material/process combination in terms of component design and recyclability.

• DFG Programme: Research Grants