Partial carbonization of aromatic polyimide films

Abstract

Aromatic polyimide films are partially carbonized between 700 and 1000°C in an atmosphere of hydrogen or nitrogeit electrical conductivity and Hall coefficient have been measured. Electrical conductivity is higher at higher measuring temperatures. The electrical conductivity σ can be expressed as σ=σ0exp(−E/kT), where k is the Boltzman constant; T is the absolute temperature; E depends upon the carbonized temperature. The experimental data show the Hall coefficient RH is negative, and this implies the majority carriers are negatively charged, i.e. electrons. The specimens are n-type semiconductors. The carrier density η can be expressed by η=A1exp(−E1/kT) and carrier mobility μ can be expressed by μ=A2exp(E2/kT). E, E1 and E2 depend upon the carbonized temperature.