Unusual Micro Carbon Rods Formed from PET Plastic via Pyrolysis and Annealing in CO2/He Co-Gas

Abstract

This study investigates the transformation of activated carbon (AC) powder, derived from polyethylene terephthalate (PET) through pyrolysis, into a specific type of short cylindrical carbon. This carbon-to-carbon (C-C) transformation was completed by annealing the AC powder in a co-gas atmosphere of He and CO2. This produces low-porous, amorphous, and micro carbon rods (MCR) in micron size. It is suggested that a so-far unknown growth mechanism originates from the oxidation role of CO2, initiating the curving of polycyclic aromatic hydrocarbons (PAHs) sheets. This annealing step was followed by layer-by-layer sheet stacking steps to render the thick rods. This thickness is also created by the simultaneous occurrence of rare carbon nanotubes, supposedly formed initially from curling a small sheet of PAH surrounding carbon nanoparticles to create a tube template for subsequent cylindrical growth. This is the first example of CNT growth through C-C transformation rather than the other vapor deposition routes. As the main product, MCR is amorphous and fairly porous, with an average aspect ratio greater than 10, which possesses potential applications as a mechanical reinforcing or energy-attenuation filler for different composites.