Composition-viscosity data for polymer thickened aqueous
solutions,63 together with reliable theoretical models
to predict the effect of the dispersed phase,64 were
used to construct equations of the type \(log(\eta)=a+bx_{n}+c\phi\) (average relative error of 22%), for
each polymer, and for both \(\eta_{1}\ \)and \(\eta_{2}\) (\(\phi\) is
the mass fraction of oil phase). Since only one polymer is used, mixing
rules are not needed. Fatty alcohols were used at a 2-4% concentration.
As indicated above, all the
formulations also included a fixed amount of mandatory ingredients,
namely water, humectant (3% Glycerol) and preservative (0.7%
Cosgard®).
Optimization problem : Product design variables and short
formulation of the optimization problem for both case studies - in the
form of (3) - are shown in Table 2.
Table 2. Product design variables and initial problem
formulation