The results from these assays combined with the yield stress
test provides ideal conditions for the stress sweep test and frequence
sweep test. The stress sweep test defines the interval of
tension required to induce linearity in the emulsion. The analysis
demonstrated that the emulsions were linear from 0.1 to 10 Pa
(Fig. 2B). The date obtained from the stress sweep test suggested
that a tension of 1 Pa in both formulations can be used for the frequency
sweep test and creep and recovery test. Both formulations
showed a linearity range in all compounds (G0
, G00 and g) in a frequency
range of approximately 1–10 Hz demonstrated by the frequency
sweep analysis (Fig. 2D). However, emulsion 36
presented a slightly higher deformation than emulsion F due to
its lower viscosity. Moreover, the general frequency confirmed
the presence of a gel-like structure at this condition with a G0
–G00
versus frequency curve characterized by a remarkable predominance
of elasticity over the viscous behavior (G0 > G00) and
the G0 modulus being parallel to the frequency axis. The compound
(n), G0 and G00 values of sample 36 were smaller than F, which indicates
that formulation 36 demonstrated more deformation than
formulation F. This is due to the fact that the more deformation
that is presented the less the values of these compounds n, G0
and G00 showed, for the same shear stress at a specific time (Dolz
et al., 2008). Samples 36 and F both demonstrated viscoelastic
properties. However, sample F (Fig. 3) was selected for further
investigation due to its adequate viscosity and because of the probability
that it might increase the residence time of the formulation
on the wound surface (desirable for wound healing purposes).