Novel carbon micro fibers and foams from waste printed circuit boards
Abstract
We report the generation of novel carbon micro fibers and foam structures during the pyrolysis of polymer rich waste printed circuit boards (PCBs) in the temperature range of 750 °C to 1550 °C under argon atmosphere. Following initial polymer degradation and the separation of most of the metallic phase, the carbonaceous residue was seen to evolve into a variety of structures. Carbon fibers started to nucleate ~ 1150 °C, had a thickness ranging between 2 and 10 microns, contained up to 95% C with morphologies ranging between tubular, foamy network and fibrous. The chemical compositions of these carbon structures was determined through X-ray microanalysis; the carbon content was close to 90% along with 5–7% oxygen, traces of phosphorus, antimony, tin and copper.
The transformation of carbon fibers to a well-defined foam structure was observed at 1250 °C; these structures were found to be stable even at higher temperatures. The formation of carbon foams/fibers was found to be not very sensitive to the relative concentration of oxide impurities present. This study shows that a potentially vast source of carbon could be recovered from the non-metallic fraction of e-waste for applications such as reduction reactions, carburization, metal–carbon composites or as a source of fuel and energy.
Keywords
Carbon fibers; Carbon foams; Waste PCBs; Carbon resource; Material recovery
Novel carbon micro fibers and foams from waste printed circuit boardsAbstractWe report the generation of novel carbon micro fibers and foam structures during the pyrolysis of polymer rich waste printed circuit boards (PCBs) in the temperature range of 750 °C to 1550 °C under argon atmosphere. Following initial polymer degradation and the separation of most of the metallic phase, the carbonaceous residue was seen to evolve into a variety of structures. Carbon fibers started to nucleate ~ 1150 °C, had a thickness ranging between 2 and 10 microns, contained up to 95% C with morphologies ranging between tubular, foamy network and fibrous. The chemical compositions of these carbon structures was determined through X-ray microanalysis; the carbon content was close to 90% along with 5–7% oxygen, traces of phosphorus, antimony, tin and copper.The transformation of carbon fibers to a well-defined foam structure was observed at 1250 °C; these structures were found to be stable even at higher temperatures. The formation of carbon foams/fibers was found to be not very sensitive to the relative concentration of oxide impurities present. This study shows that a potentially vast source of carbon could be recovered from the non-metallic fraction of e-waste for applications such as reduction reactions, carburization, metal–carbon composites or as a source of fuel and energy.Keywords Carbon fibers; Carbon foams; Waste PCBs; Carbon resource; Material recovery
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