Diffusion in ethylene polymers. I. Desorption kinetics for a thin slab

This is the authors' abstract. We don't add key points for this paper.

Theory and experiments are described for the determination of diffusion coefficients liquids in solids from desorption data. Experimentally the desorption is followed by weighing the solid specimens. The mathematical process of extracting diffusion coefficients from desorption data is examined and a numerical procedure is described which may be employed in systems in which the diffusion coefficient is concentration‐dependent. Data and analysis are presented for the diffusion of benzene and n ‐hexane in two ethylene polymers. The two polymers are representative of highly branched high pressure material and low pressure highly crystalline material. A discussion of the molecular significance of the results is given. The desorption curves obtained by numerical analysis are applicable to other systems which exhibit a similar dependence of the diffusion coefficient upon concentration.