a machine and method for pulverizing solid polymer materials into smaller particles uses a pulverizer head having a rotor with a conical contact surface and a stationary dish with a corresponding inverted conical contact surface . the dish and rotor are axially aligned and spaced apart to define a gap of fixed width between them . the material is conveyed into the gap at 0 psi from a screw extruder . rotation of the rotor generates shear forces within the gap that pulverizes the material , with the pulverized particles leaving the pulverizer head at the outer margin of the gap .