Experimental and Theoretical Study on the Desorption of Alcohols and Ketones from Polyolefins

A comprehensive dynamic desorption model has been developed to estimate the desorption rate of alcohols (i.e., tert-butyl alcohol) and ketones (i.e., 2-propanone (acetone)) from semicrystalline polyolefins under operating conditions of industrial interest. The free volume theory is employed to calculate the penetrant diffusion coefficients and their dependence on temperature and penetrant concentration. The diffusivities of acetone and tert-butyl alcohol in semicrystalline polypropylene (PP) pellets were experimentally measured at different temperatures. It was shown that model predictions are in excellent agreement with the corresponding experimental dynamic measurements of the mass desorption of the sorbed species. Moreover, it was shown that the proposed model predicts correctly the diffusion coefficient of alcohols and ketones in semicrystalline polyolefins. This work can be industrially implemented in any process which involves desorption of gaseous penetrants from solid material.