Permeation of volatile organic compounds across polymer films. Part I. Development of a sensitive test method suitable for high-barrier packaging films at very low permeant vapour pressures
Permeation von flüchtigen organischen Substanzen durch Kunststoffolien. Teil I. Entwicklung einer empfindlichen Testmethode für Barrierefolien bei sehr niedrigen Dampfdrücken
The development of a permeation measurement cell based on the classical principle of permanent gas permeation testing, according to Barrer, and application of a practical procedure for permeant adsorption and subsequent gas chromatographic determination is described. For validation of the method, the permeation of d-limonene across a biaxially oriented polypropylene film (BOPP) was measured and the results were compared with those obtained according to the pouch method and with permeation data from the literature. The applicability and high sensivity of the test method was demonstrated by measuring limonene permeation through an acrylic-coated BOPP film and a polyethylene terephthalate (PET) film and using permeants of different polarity and volatility, i.e. menthol and citronellol. From the results obtained from the uncoated and from the acrylic-coated OPP films, the permeation and diffusion coefficients of the acrylic barrier layer were calculated and shown to be three to four logari thmic orders of magnitude smaller than those of BOPP.