From: Effect of replacing polyol by organosolv and kraft lignin on the property and structure of rigid polyurethane foam
Ratio of lignin to polyol
25/75
50/50
60/40
70/30
HKL in PU foam, % (w/w)
9
19
23
28
HEL in PU foam, % (w/w)
12
25
30
36