The controlled removal of volatile organic compounds (VOCs) is an important task in polymer processing because these substances impair the properties of polymer products and are typically harmful to health and environment. This devolatilization process is often performed in rotating devices like vessels or screw extruders, especially for the treatment of high-viscous polymer melts. Despite major commercial significance, this unit operation is not fully understand since different effects interact with each other. Mass transfer from the liquid phase into the gas phase is usually rate-controlled by diffusion in the polymer melt. Two mechanisms of devolatilization can be distinguished: film degassing and bubble degassing. Film degassing occurs on contiguous free surfaces. Models to describe this process are based on the penetration theory or surface renewal theory by Higbie and Danckwerts. Bubble degassing refers to devolatilization promoted by foaming in consequence of a supersaturation of the polymer. This contribution presents the experimental investigation of devolatilization in a partial filled agitator vessel with a blade stirrer focusing on film degassing. The apparatus generate a wiped melt film on the barrel wall and a rotating melt pool at the stirrer blade contributing to mass transfer. A model substance system consisting of high-viscous polydimethylsiloxane as polymer and 1,1,2-trichloro-1,2,2-trifluoroethane as volatile is used. Thus, all experiments can be performed at ambient temperature. The driving force for the degassing is provided by reducing the partial pressure in the gas phase with a nitrogen gas flow. The concentration of volatiles in the melt is measured by thermogravimetric analysis. The stripped volatiles were recovered and weighted by use of cold traps. The results of both methods are compared with each other. A model for the devolatilization is developed and the results of the model are compared to the experiments.