Beach Plastics Material Processing

Challenge

Beach plastics collected during clean-ups often comprise mixed materials contaminated with sand and organic matter, complicating recycling efforts. Implementing the Beach Clean 2.0 methodology, which emphasises sorting at the source, streamlines material flow and polymer purity, critical factors for effective mechanical recycling and the development of circular plastic systems.

Approach

Rathlin Island beach clean plastics were sampled and analysed using infrared spectroscopy, revealing substantial quantities of polypropylene twine, polyethylene rope, and mixed rigid plastics. Polypropylene twine was cleaned, dried, and processed into filament through a twin-screw extruder, successfully 3D printing a test object.

Outcomes

International students reprocessed cleaned, dried polypropylene twine by hand-feeding it into a twin-screw extruder during a summer school. The initial extrudate was chipped and re-fed, achieving a uniform filament diameter crucial for 3D printing. Despite limited production, the filament successfully printed a test object on an entry-level 3D printer.

Learnings

This exercise provided students with hands-on experience in polymer processing, material characterisation, and circular design principles. Despite residual sand and organic contamination, the final filament typically achieved a diameter of 1.75 mm — indicating the technical viability of the concept for producing 3D printing filament from recovered beach plastics.

Impact

By applying the Beach Clean 2.0 methodology and identifying valuable 3D printing feedstock, the project showed that beach plastic can become functional material. A printed test object demonstrated potential for repair and reuse on Rathlin Island, highlighting how citizen science and education can advance circular solutions for coastal communities.