An original automated desorption apparatus for measuring multi-component sorption properties of barrier polymer films

Barrier polymer films are characterized by very low sorption levels which can nevertheless vary by several orders of magnitude depending on the absorbed solvent. Quantitatively determining their sorption properties is a true challenge with key related applications in packaging or automotive industry. This paper describes a new automated desorption apparatus developed for analyzing multi-component sorption in barrier polymer materials. The main characteristics of this automated apparatus, coupling a desorption mini-oven with on-line chromatography, are discussed with respect to the strong technical limitations imposed by these particular polymer/solvents systems. A sensitivity of 1 μg was easily obtained for the desorbate sample. Associated with a progressive rise in temperature of the polymer films, this very high sensitivity enabled to assess the sorption properties of two barrier materials (HDPE - high density polyethylene and EVOH - ethylene-vinyl alcohol copolymer) for fuel model mixtures (ethanol/i-octane/toluene) over a wide range of compositions typical for their use in multi-layer fuel tanks.