Study of the structural and electrical properties of polypropylene-titanium dioxide composite

Abstract

Polypropylene (PI'}-titanium dloxidc (Ti02) composites with difterent wcight ratio ofPP and Ti02 were prepared by extruSIOn moulding technique, XRD, OTAI TGA and lR spectroscopy wcre performed for structural analysis of the I'P and composites. The UV-Visible absorption spectroscopy, I-V and I-T measurements on PI' and composites were performed to understand the optical and electrical behaviour ofthe matenals The XRD study indicates the presence of defects between the crystallites in fibrils and I or imperfection in the ordered phase ofPP. TiO) is found to be diffused into the crystalline rcgion of PP. A decrease in the crystallite sin: is consistent with a decrease of fractlOnal crystallinity of the composites with thc increasc of -ri02 contcnt. No ncw 1R absorption band appcars due to the inclusion of Ti02 in PP CH) and C-C groups remain unchangcd where (lnly C-H bond ISaffected due to the inclusion of Ti02 in PP, In the DTAffGA investigation all the composite samples show a melting temperature of 430 K .The changc of exothenn temperatures indicates a structural modification in the PP owing to inclusion of Ti02. SPT-l is found to hc themJa\1y most stahle. In the UV-VIS absorption it is found that the band gap of composites is less than that of PP . Indirect transition energy gap, in sample SPT-l to 4, suggests the presence of two-step transition process in composites. IndIrect energy gap increases and direct energy gap decreases with the increasing percentage ofTi02 in PP, From the I-V characteristics Ohmic region is (lbserved in high v(lltage region hut at low voltage region thenniomc effect ISobserved giving risc to nonunifonnity of the field distribution between the electrode and samples. The l-T characteristics show the sharp increase of conductivity at high temperature and the eXistence of shallow trap levels Thermally activated hopping eonductlon of ions between localized state is tbund to be operative III thl; matenals,