Effect of annealing on thermal & optical properties of polypyrrole

Pure polypyrrole sample (SI) was synthesized by chemical oxidation method using NaOH as reducing agent in aqueous HCl medium. T. he polypyrrole e pellet sample (S) was then annealed at 200 T for 4 hrs. The amorphous nature of both annealed and as- prepared polypyrrole samples was confirmed by XRD. FTIR spectra of both samples were taken, which indicate the significant change in annealed sample (S-2) compared to as prepared sample. Temperature dependence of effective thermal conductivity of both samples (S-1, S2) was studied by Transient plane source (TPS) technique, The effective thermal conductivity (lambda(e)) obtained for S-1 & S-2 exhibits a variation with temperature and a peak was observed for the two samples at 150 degrees C & 120 degrees C with a value 0.17 W/mK & 0.18 W/mK respectively. The shift of thermal conductivity peak of annealed sample towards the lower temperature side is explained on the basis of removal of voids and defects on annealing. The absorption spectra of these samples were recorded by USB-2000 spectrophotometer at room temperature in the wavelength range 300-800nm, From the analysis of absorption spectra, optical band gap of S-1 & S-2 were determined. It was found that the values of optical band gap for sample S-1 & S-2 are 2.39 eV&2.24 eV respectively.