Table 1.

Box-Behnken design matrix.

Treatments	Coded			Variables
	X 1	X 2	X 3	Tapioca Starch Content (%)	Maleic Anhydride Content (%)	Screw Speed (rpm)
1	−1	−1	0	10	4	40
2	1	−1	0	30	4	40
3	−1	1	0	10	16	40
4	1	1	0	30	16	40
5	−1	0	−1	10	10	35
6	1	0	−1	30	10	35
7	−1	0	1	10	10	45
8	1	0	1	30	10	45
9	0	−1	−1	20	4	35
10	0	1	−1	20	16	35
11	0	−1	1	20	4	45
12	0	1	1	20	16	45
13	0	0	0	20	10	40
14	0	0	0	20	10	40
15	0	0	0	20	10	40