PREPARATION OF SEMICONDUCTING CARBON-FIBER BY PYROLYSIS OF POLYACRYLONITRILE PRECURSOR

Semiconducting carbon fibres were prepared from polyacrylonitrile precursor by pyrolysis in an inert atmosphere in temperature range 550-800-degrees-C. The obtained fibres have an electrical resistivity between 10(4) and 10(-2) OMEGA-cm-1 and showed negative temperature coefficients. Electrical resistivity was mainly governed by the pyrolysis temperature and both electrical resistivity, rho, and thermistor constant, B, decreased with increasing pyrolysis temperature and duration. A linear relation between log-rho and thermistor constant B was observed. Chemical analysis and infrared spectra indicated that the concentration of nitrogen and hydrogen decreased and basal plane structure developed accompanying an increase in carbon content as the pyrolysis temperature increased.