Volume 3, Issue 2 (March 1975)
The Measurement of the Coefficient of Friction of Polymer Pellets Under Extruder Conditions
A modification of a friction and wear test apparatus is described which permits measurement of the coefficient of friction (COF) of polymer pellets at conditions comparable to those in the solids feed section of an extruder. A specimen holder containing three pellet-filled cylinders is rotated against a stationary plate under prescribed conditions; the effects of pressure, velocity, temperature, roughness, and surface cleanliness can be investigated. The device is connected to an electronic load cell and recorder so that a continuous record of COF versus time is obtained. The utility of the apparatus is demonstrated by measuring the change in the COF of thermoplastic pellets as a function of several test parameters.