The complex viscosity h* of pure PBS and PBS/nanoCaCO3
composites as a function of frequency at 150 C is
shown in Fig. 7. It can be seen that the PBS/nano-CaCO3
composites had a similar dependence on frequency as pure
PBS. All the samples showed the characteristic of a Newtonian
fluid in that h* kept almost constant when the frequency
was not more than 0.25 rad/s. Compared to pure
PBS, the h* of PBS/nano-CaCO3 composites was raised
significantly, and this effect was enlarged with an increase
in nano-CaCO3 content, except for the sample PBSn9.
Increased h* for PBS/nano-CaCO3 composites is a common
phenomenon for filler reinforced polymer materials, which
can be explained by the interaction between the nanoCaCO3
and PBS hindering the movement of the PBS chains.
All the samples showed the obvious dependence on frequency
that the h* decreased with an increase of frequency,
that is shear thinning, when the frequency exceeded
0.25 rad/s. This phenomenon can be explained as, the
greater the shear rate, the more quickly two molecules
moved relative to each other, which led to reduced chain
entanglement density