Evaluating the performance of internal mixers

Abstract

High intensity batch mixers trace their origin back to 1835, when the first roll mills were used by Edwin Chaffe for mixing rubber. The Banbury high intensity batch mixer followed in 1916. Many design changes to these basic rubber mixing devices have been implemented, particularly to improve the efficiency of dispersion of carbon black. But the underlying principle of operation remains unchanged. It is the repeated passage of compound through regions of high shear stress, followed by intimate mixing of the sheared material within the batch. Because of torque and heat transfer limitations, only a small portion of the compound is subject to high stress at any one time, but the overall rotor configuration ensures that the entire compound passes repeatedly through the high stress region. With a two-roll mill this process is accomplished by manually cutting and rolling parts of the batch for feed into the nip (Chapter 3).