Dr Frank Hermanutz and Dr Tanja Schneck, German Institutes of Textile and Fiber Research (DITF) Denkendorf, have won the DNFI Innovation in Natural Fibres Award 2022. The award-winning project is “PureCell – Natural fiber-reinforced composites based on pure cellulose”.

The background of this patented technology is to dissolve cellulose in an ionic liquid to facilitate the production of cellulosic matrix precursors, which are then used to manufacture composite materials. The core concept of PureCell is to use cellulosic fibers as reinforcement with a bio-based cellulose matrix, to create an economical, recyclable, and biodegradable substitute for petrochemical raw materials.

By means of the PureCell manufacturing process, cellulosic fibres or fabrics can be impregnated with a cellulose-ionic liquid solution. After a short heat treatment, the ionic liquid is washed out with water and recovered to be used again, and the resulting wet composite can be formed into desired shapes under low temperatures. Thanks to the flexible use of both cellulose fabrics and filament fibers, the final shape of these all-cellulose composites (ACCs) is highly adaptable. To close the raw material cycle, the end-of-life waste can be recycled as raw material for the production of new ACCs.

The use of renewable biopolymers is an essential component of a strategy to reduce or eliminate the use of petroleum-based materials in industrial applications. Biopolymer composites made from natural fibres such as flax, hemp or sisal are in many cases a competitive alternative to glass-fiber-reinforced plastic composites (GFRP) or aluminum. In conventional fiber-reinforced biocomposites, differences in surface chemistry result in low adhesion between the thermoplastic matrices and the reinforcing fibres. However, the composites manufactured with the PureCell process exhibit good adhesion between the reinforcing fibers and the matrix due to their chemical similarity, since cellulose is also used as the matrix. Thanks to the fibre/matrix adhesion, these composites achieve very good mechanical properties.

The technology is an environmentally friendly process because the ionic liquid can be recycled quickly, with low energy consumption and with a high degree of purity and can be reused for further ionic liquid spinning processes.

The award will be presented at the annual meeting of DNFI during the next Heimtexil fair (11/12 January 2023).

More information: www.dnfi.org

Photo: PureCell – pure composite material made from cellulosic tyre cord fibres (left) and natural fibres (right) from DITF Denkendorf, Photo: DITF