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Towards Distributed Recycling with Additive Manufacturing of PET Flake Feedstocks.
Helen A Little1, Nagendra G Tanikella2, Matthew J Reich2
1re:3D Inc., 1100 Hercules STE 220, Houston, TX 77058, USA.
Materials (Basel, Switzerland)
|September 30, 2020
Summary
This study demonstrates 3D printing Recycled Polyethylene Terephthalate (rPET) directly from water bottles using open-source tools. This approach advances a circular economy by enabling distributed recycling for additive manufacturing feedstock.
Area of Science:
- Materials Science
- Sustainable Manufacturing
- Polymer Engineering
Background:
- Achieving a circular economy for plastics like Recycled Polyethylene Terephthalate (rPET) is crucial for environmental sustainability.
- Current recycling processes for rPET often involve energy-intensive filament extrusion for additive manufacturing.
- Distributed Recycling for Additive Manufacturing (DRAM) offers a decentralized approach to plastic waste utilization.
Purpose of the Study:
- To investigate the direct 3D printing of post-consumer rPET flakes using an open-source toolchain.
- To evaluate the feasibility of using rPET water bottles as feedstock for Fused Particle Fabrication (FPF) or Fused Granular Fabrication (FGF).
- To quantify the effects of processing steps on rPET flake characteristics and assess the mechanical properties of 3D-printed parts.
Main Methods:
- Quantified the impact of granulation, sifting, and heating on rPET flake shape and size distribution.
- Performed 3D printing tests using two distinct feed systems (external feeder and extruder-mounted hopper) on Gigabot X machines.
- Optimized 3D printing settings based on thermal characterization and conducted mechanical testing on printed parts.
Main Results:
- Successfully demonstrated direct 3D printing of rPET flakes from shredded water bottles using both feed systems.
- Identified the critical importance of moisture isolation and geometric considerations for uniform extrusion.
- 3D-printed parts exhibited mechanical strength adequate for various applications, though lower than optimized fused filament due to flow inconsistencies.
Conclusions:
- Direct 3D printing of rPET from water bottles using FPF/FGF is feasible with open-source technology.
- The study highlights pathways for enhancing the circular economy through DRAM.
- Further research is needed to improve printing consistency and establish rPET water bottles as a widespread DRAM feedstock.
