Table 4. Experimental Design.

no.	pH of core material	microcapsule dosage (%)	pre-pressure (%) (σmax)	particle size (μm)
1	7	2	40	300
2	7	4	60	150
3	7	6	80	100
4	8	2	60	100
5	8	4	80	300
6	8	6	40	150
7	9	2	80	150
8	9	4	40	100
9	9	6	60	300