Polyaniline/lignin blends: thermal analysis and XPS

Polyaniline (Pani) base and Kraft lignin (Lig) blend films have been prepared using the solvent evaporation method. The highest lignin concentration used was of 36% (m/m). The thermal behaviour of free standing Pani and of Pani/Lig blends was characterized using thermogravimetric analysis (TGA) and DMTA techniques. The TGA results indicate that Pani/Lig blends have greater thermal stability than the pure polymers. The dynamic mechanical analysis (DMA) experiments indicated that the addition of lignin in the blend occur an impairment of rotation of part of the Pani chain. The possibility of interactions between Pani and lignin is discussed through X-ray photoelectron spectroscopy and DMA measuring. These interactions can occur between Pani chain amine nitrogen and carbonyl group present in the lignin and also between imine nitrogen and hydroxyl groups of lignin.