Visualisation studies of flow of rubber in an internal mixer

The visualisation study of the dynamics of flow in an internal mixer was undertaken by using a laboratory-scale Banbury mixer with a transparent plastic chamber. The elastomer used was a silicone rubber (ICI grade SE 33) which provided a satisfactory rubbery behaviour and enabled cinematography to be used. The detailed characteristics of flow patterns in the mixing chamber were determined by the movement of coloured non-dispersible markers. For the purpose of analysis four regions inside the mixing chamber were identified. The region in front of the rotor wings, the void region, the S-shaped region and the bridge region. The movement of material in each of these regions has been determined separately for a range of rotor speeds and fill factors, followed by the interaction between the regions. [Continues.]