Carbon fiber from isotropic petroleum pitch doped with carbon nanotubes

Abstract

The comprehensive investigation of surface morphology, internal structure as well as physical and physico-mechanical properties (heat conductivity coefficient, electric resistance, tensile strength, Young modulus) of carbon fiber (CF) prepared from petroleum tar based isotropic pitch is shown in this paper. Pristine isotropic pitch was doped with different content (0 – 1.0 wt. %) of ultralong double-walled carbon nanotubes (CNT) with single filament length more than 10,000 nm. The carbonization (2000 °C) and graphitization (2500 or 2800 °С) were used as heat treatment procedures for extruded CF. It was shown that CNT content increase leads to different effects. Thus, in comparison with non-doped CF the heat conductivity coefficient increases (from 6.61 to 12.72 W/(m·K)) while the electric resistance decreases (from 33.90 to 5.41 μΩ·m). However, this leads to CNT distribution inhomogeneities through the CF filament volume, which in turn results in degradation of physico-mechanical properties. Typical CF filament surface and structure defects (overstretching, protrusion, hollow) are shown in dependence of CNT content in pitch material.