Determination of the nitrogen gas transmission rate (N2GTR) of ethylene vinyl alcohol copolymer, using a newly developed permeation measurement system

The oxygen (O2) barrier properties of ethylene vinyl alcohol copolymer (EVOH) have been widely investigated, but for other gases the available data are usually limited to dry conditions due to limitations in measurement equipment. Innovative permeation measurement systems with low detection limits are required to determine the gas transmission rate (GTR) of other gases, such as nitrogen (N2) at varying temperature and relative humidity. This study presents the design and development of a versatile permeation measurement system consisting of two subsystems: a permeation system and a detection system using gas chromatography and a pulsed discharge helium ionization detector. The measured O2GTR and N2GTR of three different 20 μm-EVOH grades containing 32, 44 and 48 mol% ethylene are in good accordance to those obtained on validated MOCON OX-TRAN® modules and a GC-differential pressure method respectively, with differences within the analytical uncertainty of each method.