Drag induced pressure development barrier batch internal mixers.

This paper is concerned with the design, operation and analysis of a dynamic viscous pressurization batch internal mixing apparatus. The device consists of a stationary cylinder instrumented with pressure transducers, a rotating shaft which can be fitted with various mixing cams, and two rotating flat ring retaining elements, one of which is transparent allowing for visual observations. A polydimethylsiloxane fluid was used as a test fluid throughout this work; it exhibits high shear thinning behaviour at room temperature and elasticity in the same order of magnitude with that of low density polyethylene melts. Drag-induced wall pressure distributions were experimentally obtained with different clearances and clearance profile configurations and at different shaft rotational speeds, with the mixing chamber being completely or partially filled. The experimental pressure profiles of completely filled chambers were compared with numerical calculations obtained with a FEM based two-dimensional model. A Carreau constitutive equation was used with experimentally determined constants. (from paper.)