In the near future, carbon nanotubes containing plastic parts are likely to enter the environment in large quantities and, due to their resistance to degradation, the environmental impact may be even more important than that of similarly shaped plastic products. Thus, there is an immediate need to examine and understand the effect of recycling on the properties of polymer/carbon nanotube composites in order to develop sustainable recycling technologies.
In this paper, polypropylene filled with different levels of multi-walled carbon nanotubes (MWCNTs) manufactured by injection molding was closed-loop recycled in order to investigate the effect of recycling and reprocessing on its rheological, electrical and mechanical properties. Preliminary results show that the PP/MWCNT composites keep the flow performance after mechanical recycling. Moreover, the stress and strain at break increase after one reprocessing cycle (mechanical recycling coupled with injection molding) whereas no statistically significant changes in electrical conductivity, Young modulus and tensile strength of the PP/MWCNT composites filled with 1, 3 and 5 wt.% were observed.