Polyvinylidene fluoride (PVDF)-poly(methyl methacrylate) (PMMA)-expanded graphite (ExGr) conducting polymer blends: Analysis of electrical and thermal behavior

Abstract

Polyvinylidene fluoride (PVDF)-20 wt% poly (methyl methacrylate) blend has been synthesized by solution blending method. Expanded graphite has been synthesized by microwave irradiation of commercial expandable graphite. With varying concentration of expanded graphite (ExGr) in PVDF-20 wt% PMMA, series of blends are synthesized. The electrical percolation threshold has been observed to be less than 1 wt% ExGr which is due to the formation of graphite nanosheets. The conducting blend system exhibits typical percolation behavior. The thermogravimetric analysis shows two step degradation in PVDF-20 wt% PMMA blend system. This is due to the individual degradation of PMMA and PVDF main chains respectively. The thermal stability of the blend system with 1 wt% ExGr incorporation in PVDF-20 wt% PMMA is increased by 11 °C corresponding to main chain degradation of PVDF. The result proves existence of strong interaction between ExGr particles and the polymer. The DSC analysis shows very clearly the existence of electroactive gamma phase both in PVDF-20 wt% PMMA with and without ExGr particles as there is an additional high temperature melting peak apart from that of the melting peak at 167 °C. This result is confirmed through XRD also. The blend system is characterized by XRD, TGA, DSC and FTIR.