Researchers at Hochschule Bremen (HSB) City University of Applied Sciences have developed a way of turning harmful packaging waste into a usable 3D printing material.
With plastic packaging disposal soaring across Germany (and around the world), the team have come up with a means of recycling leftover polypropylene into an extrudable filament. By adding reinforcing fibers, it’s thought that this feedstock could one day be deployed in automotive or aerospace 3D printing. But even in its current form, the material is being seen as a way of better reusing waste byproducts – a process critical to greener manufacturing.
“Increasing the demand for recycled materials is important,” explained Dr. Silke Eckardt, a professor focusing on sustainable energy systems and resource efficiency at HSB. “Especially with regard to climate change, we need to think about resource efficiency. The circular economy is becoming more and more important.”
Over the last 30 years, the HSB team say that plastic waste has risen from 2.1 million to 5.6 million metric tons (and that’s just in Germany). Recycling is also a challenge – it’s much easier to reuse pre-production plastics, as after manufacturing, polymers often become dirty or they get combined with other materials, so require separation into their constituent parts.
To get around these issues, the researchers have carried out a feasibility study in which they ground, washed, and separated polypropylene waste byproducts at a sorting plant. Using a combination of floatsink separation, near-infrared technology and repeat grinding, they were ultimately able to sieve out a material with 99.8% purity, as well as high resilience and flexibility.
These polypropylene flakes were later recycled using an industrial extruder at Fraunhofer IFAM, where the team mixed it using different screw geometries, then melted, and extruded it into a 3D printable material. Using the resulting 2mm thick filament, they’ve since been able to make their first prototypes with a commercial 3D printer, proving the process’ viability.
Though their feasibility study has now come to a close, the researchers continue to work on ways of improving their material’s properties. It’s predicted that the integration of glass fibers, for example, would allow for the creation of ultra-resilient parts for demanding industries. With legal pressure also mounting for greener technologies, solutions like theirs could make a difference.
Eco-friendly 3D printing isn’t just taking off in material R&D, it’s finding applications everywhere from construction to the battery market. Find out more here.
