What is the best adhesive to use between a particle board subfloor and 3/4 in plywood on top (nailed to studs) ?
#1 What's the finished floor going to be?
#2 Studs are in a wall, joist are what the floor and ceiling are attached to.
If it's really partical board and not OSB it really needs to go before anything else goes down.
If partical board gets wet once it turns to oatmeal.
Just the rising humity under it can cause it to swell.
The only glue used should be constrution adhesive and that only goes on top of the joist, where the subflooring is nailed down.
Glue is never used between layers of subflooring or underlayment.