Abstract: High Mooney viscosity elastomers having low volatiles content, and processes for producing such elastomers, are provided herein. In particular aspects, the elastomers are metallocene-catalyzed elastomers, such as mEPDM elastomers. Processes for producing such elastomers include devolatilization of an elastomer stream comprising such elastomers, using a kneader. The kneader is counterintuitively operated such that the internal agitating paddles rotate at relatively low speeds. It is believed these low speeds help maintain the elastomer stream as a toffee-like composition, preventing the elastomer stream within the kneader from becoming a crumbly composition, which is difficult to devolatilize.