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This study examines the changes in physical and mechanical properties of acrylonitrile butadiene styrene (ABS) when manufactured using fused filament fabrication (FFF) 3D printing across multiple recycling phases. Tests were carried out initially using virgin ABS, which subsequently underwent two successive closed-loop filament extrusion and 3D printing phases. For each endpoint manufacturing phase, samples were examined to monitor the changes in thermal characteristics, mechanical properties, and polymer degradation. It was found that there was a series of physical changes of the polymer, which resulted in reduced melt flow, increased glass transition temperature, and the generation of carbonyl groups, which may be attributed to the thermal oxidative breakdown of both styrene acrylonitrile (SAN) and butadiene components of ABS. The recycled polymer also showed a reduction in both tensile and compressive strengths compared to the virgin material. However, compared to one-time recycled ABS, two-times recycled ABS showed increased strength, implying that increased recycle state of the polymer may be advantageous with respect to mechanical properties and potential manufacturing applications. This study ultimately demonstrates the potential to leverage additive manufacturing (AM) toward a closed-loop manufacturing paradigm by using waste ABS across several life cycles.

<p>In this study we aim to investigate recycling of waste plastics products into filaments for use in a typical FDM 3D printing system. We investigate the parameters relating to control of the filament thickness to a variety of different plastic types, which include HDPE and ABS. Following filament generation, parameters were investigated to optimise the print parameters to produce a variety of demonstration models, which test the print resolution. Results suggest that the proposed supply chain can allow for highly repeatable ABS and HDPE filament generation with a diameter of 1.74 ± 0.1mm and 1.65 ± 0.1mm respectively. Ultimately, the production of usable filaments can provide a viable means of consuming waste plastics and reducing the burden of increased landfill. </p>

Capillary forces in microfluidics provide a simple yet elegant means to direct liquids through flow channel networks. The ability to manipulate the flow in a truly automated manner has proven more problematic. The majority of valves require some form of flow control devices, which are manually, mechanically or electrically driven. Most demonstrated capillary systems have been manufactured by photolithography, which, despite its high precision and repeatability, can be labour intensive, requires a clean room environment and the use of fixed photomasks, limiting thereby the agility of the manufacturing process to readily examine alternative designs. In this paper, we describe a robust and rapid CO2 laser manufacturing process and demonstrate a range of capillary-driven microfluidic valve structures embedded within a microfluidic network. The manufacturing process described allows for advanced control and manipulation of fluids such that flow can be halted, triggered and delayed based on simple geometrical alterations to a given microchannel. The rapid prototyping methodology has been employed with PMMA substrates and a complete device has been created, ready for use, within 2–3 h. We believe that this agile manufacturing process can be applied to produce a range of complex autonomous fluidic platforms and allows subsequent designs to be rapidly explored.

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