MaH-based blends show lower zero shear viscosity
compared to GMA based ones with PLA/HYT/EMA-GMA showing the highest of all.
The zero shear viscosity
values for PS composites at different temperatures and concentrations are given in Fig.
The materials of the first group have a lower zero shear viscosity
than the extruded, unmodified and linear PLA.
Incorporation of both calcium carbonate types increased the zero shear viscosity
, which is typical of composite materials, however, [[eta].sub.0] values recorded for the LLDPE-mCaC[O.sub.3] composites showed lower values at higher filler concentrations.
Figure 4 is a master curve, which displays zero shear viscosity
versus molecular weight on a log-log scale for all samples in both trials.
The longest relaxation time or the zero shear viscosity
are known to be a power function of the weight average molecular weight to an approximate power of 3.4 for linear polymers.
An increase in the zero shear viscosity
([[eta].sub.0]) of a run compared with the parent PP indicates higher MW, which can be because of the presence of LCBs.
The dependence of the zero shear viscosity
or the longest relaxation time on the weight average molecular weight for various polymers, including IM, was shown in earlier experimental work to follow a power law relationship (refs.
In this context, the rheological behavior of PA 6 and PBT was examined in oscillatory and steady shear, that is, both methods were combined and used to measure zero shear viscosity
and shear thinning behavior to characterize the flow behavior completely.
The effect of zero shear viscosity
on the bubble growth was simulated and the results are shown in Fig.
where [[eta].sub.0] is the zero shear viscosity
, in is the high shear rate power-law exponent, a is the transition width parameter, [lambda] is the characteristic time, [T.sub.ref] is the reference temperature, and T is the gauge temperature.
where [[eta].sup.0] is the zero shear viscosity
, and [G.sub.i] and [[lambda].sub.i] are the discrete relaxation modulus and discrete relaxation time, respectively.