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The decomposition kinetics of the pure polyaniline (PANI), PANI/CeO2 composites, and PANI/Dy2O3 composites were investigated using thermogravimetry (TG) technique under air atmosphere. Two isoconversional methods and multiple linear regression method were used for the evaluation of kinetic parameters from the TG data of different heating rates. The estimation of activation energy values shows that the addition of CeO2 significantly enhances the thermal stability of PANI matrix, while the presence of Dy2O3 slightly reduces the thermal stability of the final composites. The kinetic analysis results show that the kinetic model for the decomposition process for PANI is D3 and for the two kinds of composites is F1–D1.

Polyaniline/rare earth oxide composites (PANI/La2O3 and PANI/Sm2O3) were synthesized by in situ polymerization at the presence of sulfosalicylic acid (as dopant). The composites obtained were characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability of the composites was investigated by thermogravimetry (TG) and derivative thermogravimetry (DTG). The electrochemical performance of the composites was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results of FTIR, XRD, SEM, CV, and EIS show that the structure of composite has changed greatly when rare earth oxide content is >0.7 g (PANI/La2O3[w/w(92.7/7.3)] and PANI/Sm2O3[w/w(96.2/3.8)]) and the PANI in the composite has transformed into pernigraniline base (non-conducting state) from emeraldine base (conducting state). TG-DTG analysis indicates that the thermal stability of composite was higher than pure PANI, which is attributed to the interaction between PANI and rare earth oxide.

Polyaniline (PANI)/CeO2 composites were prepared by adding CeO2 powder into the polymerization reaction mixture of aniline. Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD) were used to characterize the composites. Thermogravimetry (TG) and derivative thermogravimetry (DTG) were used to study the thermal stability of the composites. IR and XRD results show that interaction exists between PANI and CeO2. This interaction maybe is hydrogen bonding action between the hydroxyl groups on the surface of the CeO2 and the imine groups in the PANI molecular chains. TG–DTG analysis indicates that the thermal stability of the composites is higher than that of the pure PANI. The improvement in the thermal stability of the composites is attributed to the interaction between PANI and CeO2, which restricts the thermal motion of PANI chains and shields the degradation of PANI in the composites.