Microstructural features, spectroscopic study and thermal analysis of potassium permanganate filled PVA–PVP blend films

Abstract

Potassium permanganate (KMnO4) filled polyvinyl alcohol (PVA)–polyvinylpyrrolidone (PVP) polymeric blend films have been prepared by solution casting technique, with filler levels (FL) varying from 0.01 up to 4.70 mass%. The microstructural features, thermal properties and spectroscopic properties of these films have been studied using powder XRD, AFM, Fe-SEM, DSC, TG and FTIR. FTIR spectra for filled samples indicated a major molecular structural modification, involving conversion of the hydroxyl (OH) group into ketones at higher FLs. The bands showed a clear distortion in the wide OH band especially at higher FLs of 3.80 mass% and 4.70 mass%. This is confirmed from the TG scans, whose thermal degradation signature reveals multiple stages of degradation for FL of 2.8 mass%, 3.8 mass% and 4.7 mass%. The DSC, TG and DTA curves revealed that value of T g was found to decrease on addition of filler in the PVA–PVP blend, whereas the thermal stability of the filled samples was found to increase. The XRD results revealed that the incorporation of KMnO4 in PVA–PVP blend made the sample more amorphous. At low FLs, AFM and SEM micrographs show evidence for formation of nano-particles in the host polymeric material only at the lowest FL of 0.01 mass% with uniform dispersion of nano-structures, whereas at moderate FLs, there are micro-structures in the polymeric host, followed by agglomeration of filler induced chemical species as the FL increases beyond 2.8 mass%. Therefore, KMnO4 filled PVA–PVP blend films show desirable properties expected from a good solid polymeric electrolyte, for FLs below 1.5 mass%.