Little Helen A, Tanikella Nagendra G, J Reich Matthew, Fiedler Matthew J, Snabes Samantha L, Pearce Joshua M
re:3D Inc., 1100 Hercules STE 220, Houston, TX 77058, USA.
Department of Material Science and Engineering, Michigan Technological University, Houghton, MI 49931, USA.
Materials (Basel). 2020 Sep 25;13(19):4273. doi: 10.3390/ma13194273.
This study explores the potential to reach a circular economy for post-consumer Recycled Polyethylene Terephthalate (rPET) packaging and bottles by using it as a Distributed Recycling for Additive Manufacturing (DRAM) feedstock. Specifically, for the first time, rPET water bottle flake is processed using only an open source toolchain with Fused Particle Fabrication (FPF) or Fused Granular Fabrication (FGF) processing rather than first converting it to filament. In this study, first the impact of granulation, sifting, and heating (and their sequential combination) is quantified on the shape and size distribution of the rPET flakes. Then 3D printing tests were performed on the rPET flake with two different feed systems: an external feeder and feed tube augmented with a motorized auger screw, and an extruder-mounted hopper that enables direct 3D printing. Two Gigabot X machines were used, each with the different feed systems, and one without and the latter with extended part cooling. 3D print settings were optimized based on thermal characterization, and both systems were shown to 3D print rPET directly from shredded water bottles. Mechanical testing showed the importance of isolating rPET from moisture and that geometry was important for uniform extrusion. The mechanical strength of 3D-printed parts with FPF and inconsistent flow is lower than optimized fused filament, but adequate for a wide range of applications. Future work is needed to improve consistency and enable water bottles to be used as a widespread DRAM feedstock.
本研究探索了通过将消费后回收聚对苯二甲酸乙二酯（rPET）包装和瓶子用作增材制造分布式回收（DRAM）原料来实现循环经济的潜力。具体而言，首次仅使用开源工具链对rPET水瓶薄片进行加工，采用熔融颗粒制造（FPF）或熔融粒料制造（FGF）工艺，而不是先将其转化为长丝。在本研究中，首先量化了造粒、筛分和加热（及其顺序组合）对rPET薄片形状和尺寸分布的影响。然后，使用两种不同的进料系统对rPET薄片进行3D打印测试：一种是外部进料器和配备电动螺旋输送器的进料管，另一种是能够直接进行3D打印的挤出机安装料斗。使用了两台Gigabot X机器，每台都采用不同的进料系统，一台没有延长部件冷却，另一台有延长部件冷却。基于热特性对3D打印设置进行了优化，结果表明两个系统都能直接从切碎的水瓶中3D打印rPET。机械测试表明将rPET与水分隔离的重要性，并且几何形状对于均匀挤出很重要。采用FPF且流动不一致的3D打印部件的机械强度低于优化的熔融长丝，但适用于广泛的应用。未来需要开展工作来提高一致性，并使水瓶能够用作广泛的DRAM原料。
