Recyclable Composite Material for Injection-Moulded Components
A new pure grade polyethylene (PE) fibre-reinforced composite is ideal for load-bearing components and fully recyclable. The reinforcing fibres orient themselves during injection moulding.
As a part of the SusComp project, partners Fraunhofer IWM and MicroTribology Centrum µTC, together with the Freiburg Materials Research Centre (FMF) and the polyolefin manufacturer LyondellBasell, have now produced and qualified a pure grade polyethylene fibre-reinforced composite. Instead of using carbon and glass fibres, which were often the previous choice, the partners now reinforce the PE matrix with fibres made of ultra-high-molecular-weight PE (UHMWPE). This high-strength and abrasion-resistant material is used in medical implants such as artificial knee joints.
Fibres orient themselves during injection moulding
Researchers at the Materials Research Centre at the University of Freiburg have developed a new process for manufacturing the material by injection moulding. It works by distributing different catalysts, which can be used to precisely produce PE in different chain lengths that are finely distributed along the same catalyst carrier. In the subsequent synthesis of PE using ethylene polymerisation, mixtures of low, medium and ultra-high molecular weight PE, known as reactor blends, are simultaneously produced on this catalyst. According to the researchers, this trick can be used to directly produce PE blends during polymerisation that can be injection-moulded easily. The reinforcing fibres orient themselves in the desired direction during injection moulding, ensuring mechanical strength. The researchers also recycled samples of the material 10 times, while still obtaining the same quality.