I am interested in getting fine powder of polyvinyl alcohol (PVA). I purchased grains which are 0.2-0.5 mm in length because I could not get anything finer from the estabilished vendors (Alfa Aesar, Sigma Aldrich, ThermoFisher etc).
I tried using conventional pestle and mortar, but I could not grind it up at all. I also considered ball milling, but that was ineffective because the increased temperature made the PVA soft.