A method for evaluating and controlling a mixing process for polymer-based compounds includes the steps: obtaining initial starting conditions and values for viscosity dependent parameters; increasing batch temperature by a differential amount; calculating mixing parameters such as batch temperature, dispersion, viscosity, and torque based upon fundamental kinetic, thermodynamic, and theological models; determining whether an endpoint or end points of one or more mixing parameters has been achieved; and changing one or more conditions so as to achieve the desired endpoint(s).

A closed mixer includes a mixing chamber, a pair of rotors, and a pressing ram. The pressing ram is moveable between a resting condition, which allows introduction of material into the mixing chamber, and a working condition. A method of processing polymer-based mixtures and compounds in the closed mixer includes introducing material into the mixing chamber, moving the pressing ram from the resting condition to an upper end-of-stroke position, and moving the pressing ram from the upper end-of-stroke position to a lower end-of-stroke position. A position-time profile of the pressing ram is controlled during moving the pressing ram from the upper end-of-stroke position to the lower end-of-stroke position.