FRICTION AND ITS EFFECT ON THE MECHANICAL-TO-THERMAL ENERGY-CONVERSION DURING EXTRUSION OF POLY(VINYLIDENE CHLORIDE)

Solid state friction reduction has been found to be an effective metho d for extrusion stabilization of a high coefficient of friction (COF) thermally sensitive polymer. A poly(vinylidenechloride) copolymer (PVD C) was studied alone and blended with various polyolefins to change it s frictional behavior. COF of the polymer rubbing on a metal surface w as measured under conditions typical of an extrusion process. These re sults correlated well with the measured mechanical energy consumed dur ing extrusion. Of the polyolefins studied, high and low density polyet hylene were found to be very effective for lowering friction and impro ving extrusion performance of the PVDC. Polypropylene was found, to be much less effective. Interface temperature where melting occurs due t o frictionally generated heat has been experimentally shown to be a fu nction of COF and the bulk metal temperature.