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Additive diffusion from LDPE slabs into contacting solvents as a function of solvent absorption
Author(s) -
Helmroth I. E.,
Dekker M.,
Hankemeier Th.
Publication year - 2003
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.12802
Subject(s) - cyclohexane , solvent , thermal diffusivity , diffusion , heptane , absorption (acoustics) , low density polyethylene , chemistry , materials science , polymer chemistry , thermodynamics , analytical chemistry (journal) , chemical engineering , polyethylene , organic chemistry , composite material , physics , engineering
This article describes the simultaneous diffusion of a migrant and a solvent in low density polyethylene (LDPE). The migrant (Irganox 1076) moves out of the slab, while the solvent (isooctane, n ‐heptane or cyclohexane) moves inwards. Solvent absorption was measured separately by following the increase of the mass of the slab in time. It can be described by the Fick diffusion equation with a diffusivity depending on the solvent concentration, and an interface concentration depending on time. The final absorptions were 12% for isooctane, 14% for n ‐heptane, and 29%for cyclohexane. Additive concentrations in the slab were determined at different positions by microtoming. Experiments were done for several contacting times. The concentration profiles were strongly affected by the solvent. A larger local solvent concentration increases the diffusivity of the migrant. The Fick equation with a migrant diffusivity depending on the solvent concentration gives a good description for the results with isooctane and n ‐heptane. The description is less good for the measurements with cyclohexane (when the polymer swells strongly). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1609–1617, 2003