Polymer International 25 (1991) 21 1-217 Modelling Permeation of Modified Atmosphere Gas Mixtures through a Low Density Polyethylene Package Film M. Ilter," M. kilgen*b & N. Orbey" Department of Chemical Engineering, Department of Food Engineering, Middle East Technical University, 0653 1 Ankara, Turkey (Received 20 March 1990; revised version received 4 December 1990; accepted 16 January 1991 Abstract: Permeation of individual gases through a low density polyethylene package film with C0,-N, and CO,-O,-N, mixtures was simulated with a simple mathematical model. Permeabilities of carbon dioxide were of the order of 10- l2 m3/sm2atm/m with CO,-N, systems. Including oxygen in the system did not change carbon dioxide permeabilities. Permeabilities of oxygen were of the order of magnitudt of lo-' m3/s m2atm/m with this system. When a C0,-0,-N2 mixture was humidified no substantial change was observed in CO, permeability, but the 0, permeability decreased almost 10 times. These results and the mathematical model presented may help in the modified atmosphere package design to increase the shelf life of produce. Key words: permeation, modified atmosphere, modelling. NOTATION Cc Carbon dioxide concentration in the down- stream side of the diffusion cell (kgmol/m3) Cc,up Carbon dioxide concentration in the up- stream side of the diffusion cell (kgmol/m3) Co Oxygen concentration in the downstream side of the diffusion cell (kgmol/m3) co.u, Oxygen concentration in the upstream side of the diffusion cell (kg mol/m3) Cc Carbon dioxide concentration in the polymer film (kg mol/m3) Co Oxygen concentration in the polymer film (kg mol/m3) Dc Diffusivity of carbon dioxide in the polymer film with C0,-N, mixtures (m2/s) & Diffusivity of carbon dioxide in the polymer film with C0,-0,-N, mixtures (m2/s) Do Diffusivity of oxygen in the polymer film with C0,-0,-N, mixtures (m'/s) * To whom all correspondence should be addressed. HC HO NC L " Constant in eqns 3(a) and 3(b) Constant Thickness of the polymer film (m) Carbon dioxide flux through the polymer film (kg mol/m2 s) Nitrogen flux through the polymer film (kg mol/m2 s) Oxygen flux through the polymer film (kg mol/m2 s) Permeability of carbon dioxide (m3/s m2atm/m) Permeability of oxygen (m3/sm2atm/m) Constant in eqns (12) and (13) -(41 +43)+{(41 +43)2--4143-4244)}1'2' rl = 2 'L 2 r3 Integration constant in eqn (12) 21 I Polymer International 0959-8103/91/$03.50 0 1991 SCI. Printed in Great Britain