Rheology, Crystallization Behavior under Shear, and Resultant Morphologyof PVDF/Multiwalled Carbon Nanotube Composites

Rheology, Crystallization Behavior under Shear, and Resultant Morphologyof PVDF/Multiwalled Carbon Nanotube Composites

Poly(vinylidene fluoride) (PVDF) composites containing multiwalled carbon nanotubes (MWNTs) in the range from 0.1 to 5 wt% were prepared at 220℃ using a melt-mixer. The storage modulus (G") of the PVDF/MWNT composites increased with increasing MWNT content. In particular, there was a significant increase in G" between 1 and 3 wt%. In the Cole-Cole plot, the PVDF composites with up to 1 wt% MWNTs exhibited a single master curve with a slope of 1.25, but the composites containing 3 and 5 wt% MWNTs showed a decreased slope of 1.13 and 1.03, respectively. From the addition of 3 wt% MWNTs, the yield of the PVDF composites was observed in complex viscosity versus complex modulus plot with little dependence on the loss tangent (tan δ) on the frequency was shown. Both the induction time and crystallization time obtained from the G" versus time plot decreased with increasing MWNT content. The promoting effect of the MWNTs on the overall crystallization behavior was more profound at higher crystallization temperatures. Pure PVDF and PVDF with 0.1 wt% MWNTs showed only α phase crystals, but the PVDF composites with high concentrations of MWNTs (1-5 wt%) appeared to contain a mixture of β and γ phases in addition to the α phase.

Poly(vinylidene fluoride) (PVDF) composites containing multiwalled carbon nanotubes (MWNTs) in the range from 0.1 to 5 wt% were prepared at 220℃ using a melt-mixer. The storage modulus (G") of the PVDF/MWNT composites increased with increasing MWNT content. In particular, there was a significant increase in G" between 1 and 3 wt%. In the Cole-Cole plot, the PVDF composites with up to 1 wt% MWNTs exhibited a single master curve with a slope of 1.25, but the composites containing 3 and 5 wt% MWNTs showed a decreased slope of 1.13 and 1.03, respectively. From the addition of 3 wt% MWNTs, the yield of the PVDF composites was observed in complex viscosity versus complex modulus plot with little dependence on the loss tangent (tan δ) on the frequency was shown. Both the induction time and crystallization time obtained from the G" versus time plot decreased with increasing MWNT content. The promoting effect of the MWNTs on the overall crystallization behavior was more profound at higher crystallization temperatures. Pure PVDF and PVDF with 0.1 wt% MWNTs showed only α phase crystals, but the PVDF composites with high concentrations of MWNTs (1-5 wt%) appeared to contain a mixture of β and γ phases in addition to the α phase.