High sensitivity measurements of gas transport through films for food packaging and the O2 adsorption issue

New biodegradable polymers employed for food packaging require an accurate characterization of their O2 ultra-barrier permeation rates. Methods and procedures of gas transport measurements must guarantee high sensitivity and immunity to artefacts. Within this context, this paper reports two outcomes. The first one is to demonstrate the suitability of a specific high vacuum apparatus for challenging measurements of gas permeability on new polymers for food packaging. We show that our newly developed set-up is able to achieve a minimum detectable gas throughput 2×10−9mbarl/s , which is equivalent to permeability coefficient of 7×10−11cm2/s in case of 20 μm-thick polymer film with an area of 7×10−2cm2 under a 105Pa pressure differential. The second aim is to investigate the origin of its detection limits and possible measurement artefacts obtained with this instrument. In particular, we focus on the O2 adsorption effect on the inner surfaces of the set-up.