Table 1 The coded and actual values of the variables used in central composite design
Symbol | Independent variables | Levels | ||||
|---|---|---|---|---|---|---|
− α | − 1 | 0 | 1 |  + α | ||
A | Water–oil ratio (v/v) | 3:1 | 5:1 | 7:1 | 9:1 | 11:1 |
B | Polymer content (%) | 2 | 2.5 | 3 | 3.5 | 4 |
C | PVA content (%) | 0.05 | 0.1 | 0.15 | 0.2 | 0.25 |
D | Homogenization time (min) | 3 | 5 | 7 | 9 | 11 |
Constraints | Dependent variables (Units) | Â | Â | Â | Â | Â |
Minimize | Y = particle size (nm) |  |  |  |  |  |