Table 1.

Process variables and experimental design

Factors	Variables	− 1.68	− 1	0	+ 1	+ 1.68
X1	Electric field strength (kV cm−1)	0.66	1.00	1.50	2.00	2.34
X2	Number of pulses	7.96 (8a)	25	50	75	92.04 (92)
X3	Temperature (°C)	53.18	60	70	80	86.82

X1	X2	X3	Runs
± 1	± 1	± 1	8
1.68	0	0	2
0	1.68	0	2
0	0	1.68	2
0	0	0	6

^aValues in parenthesis for pulse numbers are actual values used in the study