Cascade use of natural fiber-reinforced plastics

Project background

Natural fiber-reinforced plastics (NFRP) are increasingly being used in automotive engineering as they offer a sustainable alternative to conventional fiber composites. However, their recycling at the end of their life cycle has so far mainly been thermal, as there is a lack of suitable material-specific recycling processes. The project is therefore developing a new type of process chain that includes mechanical-thermal disintegration, targeted separation into long and short-fiber material fractions and their further processing in nonwoven and injection moulding applications.

Project objective

The project aims to use a refiner to establish a new, particularly fiber-friendly recycling route for natural fiber-reinforced plastics. The aim is to obtain high-quality long fiber fractions for the production of new non-woven semi-finished products. Shorter fibers are to be processed into injection molding granulate for cascaded reuse, which can then be used as recyclate in injection molding. Refiner pulping results in a significantly higher fiber quality, reducing the need for virgin material, lowering CO₂ emissions and reliably meeting future European circular economy requirements.

Project procedure

The Technical University of Rosenheim focuses on compounding, further processing and selected material analyses of the NFK, while the Technical University of Dresden - Institute of Lightweight Engineering and Polymer Technology concentrates on detailed material characterization, modelling and process analysis. The Dresden University of Technology - Chair of Wood Technology and Fiber Materials Engineering is responsible for the breakdown and separation of material flows and the necessary material analyses. The institutes are supported by industrial partners along the entire value chain.

Innovation

The use of mechanical or thermo-mechanical refining processes for the reprocessing of natural fiber-reinforced plastics is not yet known. The project is therefore pursuing a novel approach in which the refiner enables particularly gentle fiber disintegration so that natural fibers are retained as long and short fibers. For the first time, this opens up possibilities for simultaneous recycling of the fiber and plastic components and for processing in application-relevant hybrid components. This allows the production of recycled NFRP components that can withstand higher loads than conventionally mechanically recycled materials and opens up new options for the automotive industry to meet future guidelines for the recycling of components.