Integral sorption with induced crystallization

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Abstract
We studied the integral sorption of saturated, organic vapors in amorphous films of poly (ethylene terephthalate) (PET) using a spring balance apparatus. The penetrants employed (methylene chloride [MeCl2] and N. N. dimethyl formamide [DMF]) induce substantial crystallization of the polymer during sorption. The experimental data (mass of vapor absorbed versus exposure time) do not obey Fick's law for diffusion but reflect the influence of time dependent polymer swelling and crystallization. The data show that polymer swelling controls the penetrant transport in thin films, while molecular diffusion in the highly swollen semi‐crystalline polymer controls in thick films. Small activation energies were found for transport in thin films suggesting that ductile deformation controls the swelling in PET. A mathematical model developed previously explains the important features of the experiments.