Transforming Plastic Waste into 3D-Printed Products

Germany faces a growing challenge with plastic waste, producing approximately 5.6 million tons annually. In a bid to tackle this issue, researchers from the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) and Bremen University are embarking on a project to convert plastic packaging waste into 3D-printed products.

The amount of plastic waste has surged over the past three decades, with household contributions increasing from 2.1 million tons in 1994 to the current figure. A significant portion of this waste originates from packaging materials collected in yellow recycling bags.

While recycled filaments are already an option for many in the 3D printing community, they often fall short of the purity found in high-quality filaments. However, recent innovations suggest that significant improvements in quality are on the horizon. The project aims not only to create high-quality filament from waste but also to incorporate advanced 3D printing techniques in the recycling process.

As reported by a scientific information service, Bremen University and Fraunhofer IFAM are working to recycle hard-to-handle plastics from households and utilize them in additive manufacturing, thereby closing the product lifecycle. Dr. Silke Eckardt, a professor of sustainable energy systems and resource efficiency at Bremen University, notes the complexities involved in recycling post-consumer waste compared to production scraps, emphasizing the variability and contamination found in household waste.

Dr. Dirk Godlinski, project leader at Fraunhofer IFAM, explains that the recycled materials must meet stringent standards concerning purity, form, and size for use in 3D printing. The research team is utilizing material sourced from a sorting facility for lightweight packaging made from polypropylene. To achieve the necessary purity levels, the team processes the output from the sorting facility through a series of steps, including shredding, washing, and removing unwanted materials using a flotation separation method.

Advanced near-infrared technology is employed to identify and eliminate remaining foreign plastics, followed by further shredding to reach the ideal particle size for compounding. This meticulous process has resulted in a purity level exceeding 99.8%.

Fraunhofer IFAM is responsible for transforming the processed waste into homogenous polypropylene. The team successfully produced a consistent plastic strand by working with polypropylene flakes from the recycling process in an industrial extruder. This involved carefully adjusting various parameters such as mechanical screw configurations, temperatures, pressures, and speeds to ensure a uniform product.

The end result is a two-millimeter thick gray plastic strand that can be utilized as filament in 3D printers. The team has already achieved successful prints of components like caps. As the feasibility study concludes, researchers are refining the production process and exploring future projects. Godlinski mentions the potential to enhance the properties of the plastics further by incorporating additives like glass fibers, which could lead to the production of high-quality components suitable for industries such as aerospace and automotive.

Regulatory requirements are driving the demand for recycled materials, with the EU packaging directive mandating a recycled content quota of 10% to 35% for packaging by 2030, depending on the type of plastic and product, excluding medical and pharmaceutical items. By 2035, this quota is set to rise to between 25% and 65%.

Dr. Eckardt emphasizes the importance of increasing the demand for recycled materials in light of climate change, advocating for enhanced resource efficiency and the significance of a circular economy. Dr. Godlinski concurs, stating that maximizing the recycling of waste will lead to substantial savings in energy and resources.