DETERMINATION OF THE THERMAL-CONDUCTIVITY OF POLYPYRROLE OVER THE TEMPERATURE-RANGE 280-K-335-K

Samples of polypyrrole were synthesised under galvanostatic conditions to produce films possessing a range of electrical conductivity from 1 0(-3) to 1 0 S cm-1. The electrical and thermal conductivity of these films has been determined between 280 and 335 K. The electrical conduc tivity was measured using a four probe technique calibrated against AS TM D4496-87. Thermal conductivity was determined from measurements of thermal diffusivity, specific heat and density. Thermal diffusivity wa s determined. using a modified a.c. calorimetry technique, while diffe rential scanning calorimetry (DSC) was used to determine specific heat . The polymer's density was measured using Archimedes' principle. The results were used to calculate the Lorenz number of polypyrrole.-A com parison of the predicted behaviour and experimental results was made. Thermal conductivity is found to be large compared to that predicted f rom the electrical conductivity measurements on low conductivity films . Molecular vibration effects are found to be non-trivial and experime ntal means for measuring their contribution are mentioned. While polyp yrrole has been regarded as a ''synthetic metal'' the thermal conducti vity results show this classification is wrong.