Remediating plastic waste into carbon nanotubes

Polyethylene-based used plastics needs hundreds of years to degrade in atmospheric conditions. Thus, in addition to conventional recycling facilities for polymer waste (PW), innovative solutions are required. This paper describes a solvent-free process that converts PW such as low-density (LD) and high-density polyethylene (HDPE) into multi-walled carbon nanotubes (MWCNTs) via thermal dissociation in the presence of chemical catalysts in a closed system under autogenic pressure. Specifically, the optimization of process parameters, e.g. selection and amounts of catalysts, density effects of PE, autogenic pressure measurements, and a reaction mechanism for the growth of MWCNTs is explained. The composition, morphology, and atomic structure of the as-obtained MWCNTs are characterized employing advanced structural, spectroscopic, and imaging techniques. We have measured the unique magnetic and electrical conductivity behaviours of as-prepared MWCNTs to assess their potential applications as advanced materials. This reproducible process presents an opportunity to use PW as a feedstock for the production of MWCNTs, industrially significant value-added products. Among the known methods for the fabrication of MWCNTs, the present controlled dissociation of PW is one of the inexpensive and straightforward methods.