Cleaning of one type of material or color from an extruder by forcing it out with the new material or color or by using special purging substances. Purging is more efficient when the purging material [..]

A polymer having no crystallinity. Polystyrene is an amorphous polymer while HDPE is semi-crystalline.

The situation where properties vary according to the direction in which they are measured.

The shear rate determined in capillary viscometers without making a correction (Rabinowitsch) for shear thinning. It turns out that the apparent shear rate is equal to 4Q/p

The viscosity determined in capillary viscometry without making a correction (Rabinowitsch) for shear thinning. The apparent viscosity is equal to the shear stress divided by the apparent shear rate, [..]

Abbreviation of American Society for Testing and Materials, an association for establishing standard testing and reporting procedures.

The resistance that reduces forward flow in an extruder.

A term used in capillary viscometry to describe the excess pressure drop in the entrance to the capillary due to extensional (elongational) viscosity. It might be negligible when very long capillaries [..]

A high-intensity batch mixer composed of a "figure-eight" shaped chamber and a pair of counter-rotating rotors that masticate the materials.

Screws where a second flight (barrier), with a larger radial clearance than a normal flight, separates the solid bed from melt in the compression section. Barrier screws have significantly higher melt [..]