Polymer mixing is distinguished into phase break up / dispersion and distribution of the phases. Even though both processes take place in the same mixer, the approach needed for their study and their characteristics are different. High stresses are necessary for the phases to break up. Large strains are needed for the distribution of the broken phases, as well as complicated flow paths that lead to chaos.

Polymer mixing is one of the hottest subjects in the polymer processing industry. Intensive efforts are done to go beyond the empirical approach that is still followed in most cases. Special emphasis is given to the effect of the morphology and the phase dimensions on the mechanical properties. Understanding the mechanism of mixing leads to the understanding of the final morphology and the possibility of optimisation of the composition of the blend and the operating conditions in the mixer.