Studies on synergistic effect of CNT and CB nanoparticles on PVDF

Abstract

Poly(vinylidene fluoride) (PVDF) nanocomposites with different loading of carbon nanotubes (CNT) and carbon black (CB) were prepared by melt blending method. The conductivity and mechanical properties of the nanocomposites were investigated. The results showed that percolation threshold of CNT/CB/PVDF nanocomposites appeared at a lower concentration (1.25 vol% CNT) than that of CNT/PVDF (>2.08 vol% CNT). The tensile strength of CNT/CB/PVDF nanocomposites was also improved, with 32.1% increase compared to PVDF and 18.0% increase compared to CNT/PVDF at loading of 1.25 vol% CNT/0.96 vol% CB. To explore the synergistic effect of CNT and CB, nonisothermal crystallization and isothermal crystallization behaviors of PVDF and its nanocomposites were studied by differential scanning calorimetry, and the crystallization morphology of them was observed under the three dimensional digital microscope with the polarized model. The crystallization rate of PVDF was speeded up markedly because of heterogeneous nucleation effect of nanoparticles, and CNT and CB nanoparticles had a synergistic effect on nucleation. Polarized microscope observation confirmed that spherulite size of PVDF became smaller owing to the accelerating of crystallization, which influenced the distribution of nanoparticles. The dispersion of nanofillers in matrix was observed by scanning electron microscope. It was revealed that CB could make CNT disperse more evenly in the PVDF matrix. The synergies network of CNT and CB is suggested to build in matrix, which improved conductivity and mechanical properties of PVDF nanocomposites. POLYM. COMPOS., 36:2248–2254, 2015. © 2014 Society of Plastics Engineers