Hello, the problem with pulverizing or crushing plastics is that they need to be brittle.

This can be achieved by cooling with liquid N2 in a so-called cryo-mill. I hope this is useful.

You can also use a dry ice (solid form of carbon dioxide).

DRY IS NOT WORKING WELL WITH THE PVC POLYMERS.... WE HAVE TRIED THIS AT OUR LABORATORY BUT RESULT WAS NOT SUCCESSFUL..