It has been observed previously [1] that under the specific conditions prevailing in a reflux flask reactor, the overall rate of the transesterification reaction between an ethylene and vinyl acetate copolymer and 3-phenyl 1-propanol can be enhanced appreciably by the introduction of boiling inert hydrocarbon solvents. In the present study, the same reaction carried out under a controlled removal of vapors in a stimulator emulating a non-intermeshing counter-rotating devolatilization twin screw extruder, a significant acceleration of the reaction rate has also been observed. In agreement with the previous work [1], the intrinsic reaction mechanism and the chemical equilibrium do not appear to be affected by boiling of the inert hydrocarbon solvents, nor does the additional mechanical agitation due to the rapid bubble growth contribute to the increase of the overall reaction rate. Theoretical analysis of the results confirms that the acceleration of the reaction rate originates from the localized mass transfer effect connected to the presence of the bubble vapor-liquid interface films induced by devolatilization.