Recycled polycarbonate and polycarbonate/acrylonitrile butadiene styrene feedstocks for circular economy product applications with fused granular fabrication-based additive manufacturing

Distributed recycling and additive manufacturing (DRAM) holds enormous promise for enabling a circular economy. Most DRAM studies have focused on single thermoplastic waste stream. This study takes three paths forward from the previous literature: 1) expanding DRAM into high-performance polycarbonate/ acrylonitrile butadiene styrene (PC/ABS) blends, 2) extending PC/ABS blend research into both recycled materials and into direct fused granular fabrication (FGF) 3-D printing and 3) demonstrating the potential of using recycled PC/ABS feedstocks for new applications in circular economy contexts. A commercial open source large-format FGF 3-D printer was modified and used to assess the different printability and accuracy of recycled PC and PC/ABS. The mechanical properties (tensile and impact) following the ASTM D638 and D6110–18 standards were quantified. A weather simulation test (ASTM D5071–06) was performed to assess outdoor performance. Finally, two applications in sporting goods and furniture were demonstrated. In general, better printability was achieved with recycled PC/ABS compared to recycled PC, as well as good dimensional accuracy at printing speeds of 30 and 40 mm/s. Minimal qualitative differences and discoloration were visible on the samples after accelerated weather exposure, with results in accordance with the state-of-the-art. The rPC/ABS results from tensile tests show similar values to those of rPC for elastic modulus (2.1 ± 0.1 GPa), tensile strength (41.6 ± 6.3 MPA), and elongation at break (2.8 ± 0.9%), which are also comparable with previous studied virgin 3-D printed filaments. Similarly, impact energy (115.78 ± 24.40 kJ/m2) and resistance values (810.36 ± 165.77 J/m) are comparable in the two tested formulations, reaching similar results compared to FFF 3-D printed filaments, as well as virgin materials for injection molding. Finally, the two demonstration products in the sporting goods and furniture sectors were successfully fabricated with rPC/ABS, achieving complex patterns and good printing speeds for recycled feedstocks. It is concluded rPC/ABS blends represent a potential high-performance feedstock for DRAM, validating its use in direct FGF 3-D printing systems and potential applications for a circular economy.