A group of Finnish researchers has developed a new process that improves the recycling of textiles and other fibres.
The VTT Technical Research Centre near Helsinki has created a cylindrical extruder that can treat long fibres without cutting them. As a result, recycled materials can be used to produce long-fibre composites. So far, tests on the prototype’s performance with various plastics, fibres and textiles are said to be ‘promising’.
Suitable for mixed input
‘Many textile recycling processes are only suitable for products containing homogeneous fibres,’ says Pirjo Heikkilä, senior scientist at VTT. ‘However, textiles are often a mix of fibres and many products comprise different layers. The new extruder opens up a revolutionary opportunity to recycle mixed textiles and materials without having to separate fibres or components,’ she explains.
The prototype has a screw diameter of 30 cm instead of the 3–4 cm typically found in conventional devices of the same output. This large diameter, combined with a shallow screw channel, makes it possible to mix components of porous and lightweight materials and ensures the mixed mass is compatible with the next stage of the production process.
Heikkilä describes the extruder as ‘compact and easily transportable’. The unit is only two metres long, weighs around 1.5 tonnes, and can be mounted upright. Its design enables accurate temperature control. The design also offers cost savings because it is far less expensive than traditional mixing twin-screw extruders.
The innovation was inspired by the idea from VTT research scientist Hannu Minkkinen that materials can rotate around the device’s hollow cylinder. According to Minkkinen, the prototype has already exceeded expectations and VTT is actively looking for a commercial partner to scale up the project.
Also interesting: a recent VTT study found that 5% of all of the world’s spare parts could be stored digitally for 3D printing. Very old or rarely needed parts are especially suitable for digitalisation and 3D printing, owing to high value but low demand. Warehousing such spare parts is not viable.