VTT tests recyclable waste extruder on bread

By Jenny Eagle contact

- Last updated on GMT

VTT's cylindrical extruder. Photo: VTT.
VTT's cylindrical extruder. Photo: VTT.

Related tags: Vtt technical research centre of finland, Bread

VTT Technical Research Centre of Finland has developed a cylindrical extruder to turn problematic textiles and plastics into recyclable materials.

Its prototype has exceeded the industrial steering group’s expectations during initial testing and VTT is now looking for a partner to commercialize the technology.

Textiles & bread


An extruder is a device used in plastics factories to melt, mix and extrude paste through a nozzle.

Research scientists tested the prototype with pieces of plastic film, mixed plastic waste, textiles and bread.

As well as recycling waste, the device can produce long fiber composites and can be utilized in food and feed processing.

Behind the idea for the extruder is Hannu Minkkine, research scientist, VTT, who discovered materials can rotate around the device’s hollow cylinder.

The device was designed and the prototype built with funding from Business Finland’s and VTT’s funding instrument for commercialization of research results.

Many textile recycling processes are only suitable for products containing homogeneous fibers. However, textiles are often made of a mix of fibers, and many products are comprised of different layers​,” said Pirjo Heikkilä, senior scientist, VTT.

The extruder opens up a revolutionary opportunity to recycle mixed textiles and materials without having to separate fibers or components."

Easy to transport

The diameter of the extruder screw determines the size of the feed throat and materials the device is capable of processing.

The first prototype has a screw diameter of 30cm instead of 3cm-4cm typically found in conventional devices of the same output.

The large diameter combined with a shallow screw channel makes it possible to mix different components of problematic, porous and lightweight materials and to make the mixed mass compatible with the next stage of the production process.


Tomi Erho, principal scientist, VTT, said benefits include: it is cheaper to make than traditional mixing twin-screw extruders; VTT’s first prototype is less than two metres long and weighs 1.5 tons. It is easy to transport; the design enables accurate temperature control combined with mixing and long residence time and long fibers can be processed without cutting them.

Commercializing the device would create completely new possibilities both in terms of waste processing and novel material combinations​,” added Erho.

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