Varying shear rates were applied to multiple emulsions
to determine the flow parameters, while fitting the data
in power law equation 4:
τ ¼ K γn ð4Þ
Where τ is the shear stress, γ is the shear rate, K is the
consistency index and n is the flow behavior index.
Consistency index K is a measure of the system
consistency and it is related to apparent viscosity. Flow
behavior index n determines the degree of non-newtonian
flow behavior and varies in the range between 0 and 1.
The non–newtonian behavior of the investigated system is
more pronounced for smaller values of “n”. We measured
the viscosities of multiple emulsions at a speed of 100 to
200 rpm while applying the shear rates from 200 to 400
on each of the samples. Varying shear rates were applied
for the quality assurance of emulsions under stress conditions.
Results for the rheology of fresh sample and for
the samples that have been kept at different conditions
of storage (followed for 30 days) have been shown in
Figure 2.
Samples of multiple emulsions revealed non-newtonian
flow and shear thinning behavior with different conditions
of storage upon varying the shear rate. With an increase
in shear rate and shear stress, a decrease in viscosity could
be observed. Rheological analysis revealed excellent fits
and were found to be from 98.6 to 99.6 and the obtained
values of K and n have been shown in Table 6. It could
be seen that all the samples exhibited pseudo-plastic