engleski

Influence of liquid absorption on gas permeability of monofilms used for food packaging

Gas (O2, N2, CO2, air) permeability (using manometric method, GDP-C Brugger instrument) of polymeric monofilms: polyethylene (PE), polyamide (PA) as well as bioriented coextruded polypropylene, both metallized (BOPPcoex.met) and non metallized, (BOPPcoex) is determined at 20oC. In order to simulate the effect of food/packaging interaction on gas permeability changes the samples are subjected (10 days at 40oC) into 15 % (v/v) ethanol and 3 % (w/v) acetic acid solutions, as food simulants according to EU directive. Thermal characterization of the samples was performed using differential scanning calorimeter (DSC) on a Netzsch DSC 200 instrument. Standard deviation, average value and coefficient of variability (obtained between 1 and 2%) were determined for permeance data for analyzed monofilms. Gas permeance of the dry polymeric monofilms is from 160 to 320 cm3 m-2 d-1 bar-1. The permeance of the selected polymers treated with food simulants increased significantly compared to untreated ones. PA showed the best gas barrier properties against liquid absorption, followed by BOPPcoex.met ; BOPPcoex and PE. Generally, higher CO2 permeability, in comparison to other gases (O2, N2, and air) occurred for solvent treated samples. The highest O2/CO2 permselectivity increase, after liquid absorption, is obtained for PA film, while both BOPP films showed decreased O2/CO2 permselectivity.

acetic acid; ethanol; gas permeability; polymers; monofilms

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