n An intensive mixer originally used for rubber, and for many years used for mixing plastics such as cellulosics, vinyls, polyethylene and others. It consists of two counter rotating, spiral-shaped blades encased in segments of cylindrical housing, the housing halves joined along internal ridges between the blades. Blades and housing may be cored for circulating heating or cooling liquids. A recent adaptation of the design, with connections to feed and discharge screws, permits continuous operation. (Strong AB (2000) Plastics materials and processing. Prentice Hall, Columbus; Juran R (ed) (1986) Modern plastics encyclopedia. McGraw-Hill/Modern Plastics, New York; 1990, 1992, 1993 editions).