Measurement of volatile diffusivity in polymer particles

Most polymers must be devolatilized after their synthesis. The accurate design and operation of devolatilizers requires accurate diffusivities. A new method is developed to measure volatile diffusivities in polymers under conditions relevant to solid-state devolatilization. This method does not require knowledge of the exact solubility and makes it possible to check for non-Fickian behavior. The measurements are performed with the actual polymer particles and several volatiles can be desorbed simultaneously. The new method was applied to diffusivity measurements in polypropylene, ethylene vinyl acetate copolymer (EVA) and ethylene acrylate copolymer (EDA) granules.