It is well known that rheology is a powerful tool to examine mesoscopic structure of the CB-filled polymer systems because the viscoelastic properties are highly related to the dispersion and distribution of CB and its particle--particle interactions 120-29b The rheological behaviors of PCBp, however, have not yet been explored in detail.
However, the reported results concerning viscosity and active energy are more or less limited because both the processing and the application of PCBp require much more information on the viscoelastic flow responses, especially their influence factors.
PCBp (where p is the wt% of CB) was prepared by melt compounding with a HAAKE Polylab Rheometer (Thermo Electron, USA) at 200[degrees]C and 50 rpm for 8 min.
Figure 1 shows the FE-SEM images of the PCBp with various CB loadings.
Figure 3 shows the vG-P plots of phase angle ([delta]) as a function of the absolute values of complex modulus (|G*|) for the neat PVDF and PCBp. It is clear that the phase angle is higher than 45[degrees], indicating a flow behavior of a viscoelastic fluid for the samples with the CB loadings lower than 7 wt%.
6 to fit [C".sub.m]([omega])(w) and [C'.sub.m]([omega])(w) of the PCBp, by which the values of those parameters can be obtained.
These two functions can be used to account for the relations between [A.sub.f] and [phi] for the PCBp approximately, as shown in Fig.
The k value of CB in the PCBp in this work is approximately 6.0, just located in the common value range of the filler with irregular shape.
Figure 8a shows the DC conductivity of PCBp. A typical nonlinear percolation behavior is observed.
For PCBp, the critical volume fraction value is ca.
For PCBp, almost identical threshold values of the two percolation behaviors indicate that the CB particles are not fully detached in the PVDF matrix during melt mixing.