Researchers from the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM and Hochschule Bremen – City University of Applied Sciences have developed a method to transform plastic packaging waste from households into high-quality filament for additive manufacturing. The initiative is part of ongoing efforts to support material circularity and reduce dependency on virgin plastics.

Rising Plastic Waste and the Recycling Challenge
In Germany, household plastic packaging waste has increased substantially, from 2.1 million metric tons in 1994 to 5.6 million in 2023. Much of this waste is used only once and less than a third is currently recycled. Packaging plastics are often composed of mixed materials and contaminated, making them difficult to reprocess into valuable materials.

To address this challenge, the researchers focused on post-consumer polypropylene – a common packaging plastic – and explored its potential for use in 3D printing applications, which demand materials of consistent purity, particle size, and shape.

Purification and Processing
The process began with polypropylene sorted from mixed packaging waste streams. At Hochschule Bremen’s Laboratories for Circular Economy, the material underwent a series of cleaning and separation stages. These included washing, float-sink separation, and near-infrared sorting to remove contaminants and unwanted plastic types. The cleaned material was then ground and dried, achieving a purity level of more than 99.8%.

At Fraunhofer IFAM, the purified polypropylene was processed into filament using industrial extrusion equipment. Through careful adjustment of extrusion parameters – such as screw geometry, temperature, and pressure – the team produced a homogeneous, two-millimetre-thick strand. The strand was round and smooth in surface, meeting the requirements for direct use in commercial 3D printers.

Application and Future Development
The resulting grey filament has already been used successfully to print simple components, such as caps. Researchers are now working to optimise the production process and are considering enhancements, including the integration of additives such as glass fibres. These additions could improve the mechanical properties of the recycled filament, extending its use to more demanding applications in sectors such as automotive and aerospace.

For product and packaging designers, this development highlights the growing feasibility of using recycled feedstocks in manufacturing processes, particularly in prototyping and short-run production. The project contributes to the wider shift towards circular material systems and aligns with EU policy goals promoting recycled content in plastic packaging.

Regulatory Context
Under the EU Packaging and Packaging Waste Regulation (PPWR), plastic packaging is expected to contain between 10% and 35% recycled content by 2030, depending on the type and use case. By 2035, this requirement will increase to between 25% and 65%, accelerating the demand for high-quality recycled polymers.

Source: Fraunhofer IFAM
Photo: Fraunhofer IFAM