Table 1 Conditions with different combinations of independent variable used in central composite rotatable second order design for response surface methodology
| Treatment No. | X1 | X2 | Heating Temperature (t) | Heating Time (T) |
|---|---|---|---|---|
| 1 | −1 | −1 | 100 | 1 |
| 2 | −1 | −0.5 | 100 | 3 |
| 3 | −1 | −0.1 | 100 | 5 |
| 4 | −1 | 1 | 100 | 10 |
| 5 | 0 | −1 | 150 | 1 |
| 6 | 0 | −0.5 | 150 | 3 |
| 7 | 0 | −0.1 | 150 | 5 |
| 8 | 0 | 1 | 150 | 10 |
| 9 | 1 | −1 | 200 | 1 |
| 10 | 1 | −0.5 | 200 | 3 |
| 11 | 1 | −0.1 | 200 | 5 |
| 12 | 1 | 1 | 200 | 10 |