ABSTRACT
Very familiar is the mixing of pigment or stabilizer into a polymer: other objectives of the mixing process can be the production of a homogeneous blend or the equalization of thermal inhomogeneities. Mixing processes in different types of extruders have been extensively discussed in a book edited by D. B. Todd. In reactive extrusion, the mixing has to assure that the distance between the components is small enough that diffusion can provide complete homogenization within the time available or to assure good stochiometry within the characteristic time for the reaction. Dispersive mixing is important if the components are incompatible; distributive mixing plays a role if the components are compatible. Since in dispersive mixing the shear stress is important, dispersive mixing actions is strongly dependant on viscosities and a high viscosity of the matrix phase favors a good dispersive mixing. Much geometry is possible, with or without mixing elements and with or without interruptions of the flights.
