this invention relates to a process for carrying out continuous demonomerization and postpolymerization of polyamide 6 melts and a reactor for carrying out this process . the reactor of this invention has a cylinder with a horizontal axis around which an interior rotor shaped like a cage rotates . the reactor can be partially filled with polymer melt . there is a multitude of elements along the periphery of the rotor which partly dip into the melt and serve to convey the melt through the reactor , generate new surfaces and mix and homogenize the melt as the polymer melt undergoes demonomerization and postpolymerization under vacuum .