Optimization of Exothermic, Foaming, and Mechanical Properties of Modified Polyurethane as Filling Material for Goaf Sealing Wall

Table 2

Orthogonal test scheme of three factors and four levels (L16).

Level	Factors
	Polyether polyols a : b	Catalyst A33	Surfactant BL-8468
1	9 : 11	0.5	0.5
2	10 : 10	0.8	0.6
3	11 : 9	1.0	0.7
4	8 : 12	1.2	0.8