• C GOPALAKRISHNAN

Articles written in Bulletin of Materials Science

• Investigations of structure development, electrical and thermal properties of polyvinylidene fluoride-expanded graphite nanocomposites

From natural graphite, expanded graphite (ExGr) has been synthesized using perchloric acid. Polyvinylidene fluoride (PVDF)–ExGr nanocomposites have been synthesized through non-solvent precipitation method followed by melt crystallization at 200$^{\circ}$C and quenching in water at room temperature. The electrical percolation threshold has been found to be above 4 wt% ExGr in PVDF. With the addition of 0.5 wt% sonicated ExGr in PVDF-7 wt% graphite, the electrical conductivity is enhanced to two orders when compared to that of PVDF-7 wt% graphite. Thermogravimetric analysis proves very good dispersion of graphite nanosheets, as there exists at least 20$^{\circ}$C enhancement in the onset temperature of thermal degradation with the addition of 3 wt% ExGr in PVDF. Structure development in PVDF due to the incorporation of ExGr particles has been understood through lattice mismatch theory. The impedance decreases with increase in the concentration of ExGr in PVDF at room temperature due to the formation of conducting channels. In another set ofexperiment, annealing of solution-casted films at 120$^{\circ}$C for 5 h results in the formation of electroactive $\gamma$-phase, as confirmed through Fourier transform infrared and X-ray diffraction (XRD) analyses of representative samples. The composites are characterized by XRD, scanning electron microscopy and transmission electron microscopy.

• # Bulletin of Materials Science

Volume 45, 2022
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020