The List main evaporator features special shaft geometry with back mixed capacity and an optimized L/D ratio. As a result, an increase in energy input is possible to enhance the main evaporation. For example, the 80 to 90 % polymer solution from stir tank reactors can be flashed directly into the main evaporator. The backmixing enables a consistently high viscosity across the entire length of the machine. The resulting performance of the List technology, including generation of additional mechanical energy at low shear rates and excellent surface renewal, make it possible to achieve solvent concentrations of 10 to 20 % without localized over heating or formation of “fish eyes”. By being able to precisely control low temperatures, the List technology is well suited to handle complex processes involving temperature sensitive products.