Effect of heat treatment on synthetic carbon precursors Original Research Article

Carbonaceous materials obtained from polyethyleneterephthalate (PET), a potential precursor for polymer-based carbon, were studied after heat treatment at 750, 900 and 1200 °C in an inert atmosphere. The carbon content increases to more than 95% (w/w) already at the lowest temperature applied. The surface area decreases from 242 to 14.7 m2/g between 750 and 1200 °C, causing also a reduced pore volume and the conversion of open to closed pores. The pore structure exhibits a gate effect. The carbon matrix contains both amorphous and semicrystalline regions. The spatial extent of the latter can be described by a Maxwellian distribution with a maximum of 12 Å at the lowest and 17 Å at the highest temperature values. Increasing the temperature from 900 to 1200 °C does not increase the size of these domains but yields a more ordered carbon skeleton. In the WAXS spectrum a flat diffuse peak about 3.5–4.0 Å corroborates that the graphitic domains are of colloidal size. The immersional wetting enthalpies determined in water, methanol and benzene indicate that the surface has an amphoteric character and that the carbon structure and surface chemistry are strongly affected by the heat treatment processes.