A twin screw extruder to conduct reactive processing such as polymerization and polymer blending is used for the creation of newly functionalized polymers with very sophisticated morphology. Recent morphology control is requested at the level of nano-scale. A twin screw extruder is the most preferred device for these purposes, but must be solved the major issues of required residence time, polymer temperature and morphology control. Here the extruder design how to provide the necessary reaction temperature, residence time, intensity of mixing, and devolatilization in reactive processing is discussed. And furthermore, it is also explained that the combination of polymer blending systems and nano-scale inorganic fillers can be utilized to obtain finer morphology in polymer blending.