in the production of isobutylene - based elastomers the product obtained from the polymerization process is often in the form of a stream . described herein are an apparatus and a process for removal of hydrocarbon liquids from the elastomer . the process comprises the steps of obtaining a stream comprising hydrocarbon liquids , either solvents or diluents , and an isobutylene - based elastomer ; passing the stream through a kneader to volatize the hydrocarbon liquids from the elastomer .