Hey, it's free - give it a shot.
However, for anything to act like a proper membrane absorber, you need:
1. A cavity behind it - preferably sealed.
2. A membrane with sufficient mass to resonate at the frequencies desired. Bass frequencies require relatively high mass.
For instance, a sealed membrane absorber that is tuned to about 110Hz or so (give or take for construction details, voids, etc.) requires a 3.5" cavity behind it and 1/4" plywood face. I would suspect that you would need probably 4-6" of that foam to get the same mass as the plywood.
If you're talking about something similar to an FRK/FSK faced fiberglass, then it might work, a little bit - but not down very deep. Check out the specs for 1" FRK 703
0.18 0.75 0.58 0.72 0.62 0.35
Now 1" Plain 703
0.17 0.86 1.14 1.07 1.02 0.98 1.00
Look where you gained absorbtion - at 125Hz - but not much - and this is with something behind it that will actually give a little bit - unlike the foam. If you figure the foam will do almost nothing above 150Hz and is not dense enough to act as a membrane at bass frequencies but not porous enough to act as a pure veloctiy absorber, I'm not really seeing much point.
