SABIC & Local Motors Recycling Thermoplastic Study
With the desire to improve the circularity of large format additive manufacturing SABIC, a global leader in the chemical industry, and Local Motors, a next-generation vehicle manufacturer, has completed a joint study on the feasibility of recycling scrap thermoplastic parts and shavings from the 3D printing process. The study explored more sustainable alternatives to landfilling large, printed parts in anticipation of wider adoption of LFAM. It included analyzing the printability and mechanical properties of SABIC’s LNP THERMOCOMP AM reinforced compound, used by Local Motors, after being printed, reclaimed, ground and reprocessed into pellet form. The study determined that material from post-production parts and scrap can potentially be reused in LFAM or other processes, such as injection molding or extrusion, at amounts up to 100 percent. These insights can help identify a feasible path to circularity and an extended lifecycle for materials used by the LFAM industry.
Currently, no established value chain exists for reclaiming post-production LFAM parts and scrap. This complex sequence of steps includes managing the logistics of locating, collecting and transporting large parts to a facility capable of cleaning, cutting, regrinding and repurposing the material.
Another challenge of reusing LFAM materials is potential degradation from multiple heat cycles (grinding, re-pelletizing, re-compounding, etc.). Each step adds to the cumulative heat history, which tends to break down the polymer chains and reduce fiber length and can affect performance. These factors should be considered when identifying opportunities for material reuse.
Study Method and Results
The SABIC-Local Motors study included evaluations for printability, throughput and mechanical properties. In order to assess printability, six material samples of LNP THERMOCOMP AM compound were prepared, containing 0, 15, 25, 50, 75 and 100 percent reprocessed content, respectively. These samples were monitored for changes in throughput and melt flow rate on SABIC’s Big Area Additive Manufacturing (BAAM®) machine from Cincinnati Inc., located in the company’s Polymer Processing Development Center in Pittsfield, Mass. Each sample was used to print a single-wall hexagon, which is SABIC’s typical test part geometry for processing and material characterization. All the samples printed well, with a smooth, shiny surface and straight, even layers that demonstrated no issues with material flow.