Gas transport and thermal characterization of mono‐ and di‐polyethylene films used for food packaging

Abstract

The permeability of carbon dioxide, oxygen, nitrogen, and air through commercial monolayer and multilayer films, based on polyethylene (PE), biaxially oriented polypropylene (BOPP), and polyamide (PA), used for food packaging is reported. The influence of temperature (from 10 to 60°C) on permeability and DSC characteristics changes was also analyzed. Literature data for gas permeability of the mentioned monofilms are quite variable due to differences in additives, thermal history, and crystallinity. In this work, the highest gas permeability is obtained for PE film at the higher temperature (50–60°C). Laminates exhibit different gas permeation behavior from that of monofilms. Generally, gas solubility coefficient increases at higher temperature (with an exception of PA/PE and BOPPcoex.met/PE), being higher for monofilms in comparison with laminates, while diffusion coefficients are lower for monofilms in comparison with laminates. The temperature dependence of the permeability, diffusivity, and solubility of gases shows two different regions in PE, BOPPcoex/PE (10–40°C and 40–60°C), PA/PE, and BOPPcoex.met (10–30°C and 40–60°C) films. Correlation between activation energies for permeation and diffusion as well as heat of sorption and 17 gas properties is performed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1590–1599, 2006

Molecular modelling of oxygen and water permeation in polyethylene

“…Hence, possible changes in the PE matrix due to the additional chain-chain interactions caused by these changes are not sufficiently large to affect the oxygen solubility coefficient. Although the simulated coefficients are in the same order of magnitude of some experimental studies [4,8,60,61] they are larger than the data obtained in other studies [9,12]. The simulations also yield decreasing S with increasing temperature, which is in agreement with experimental data that shows a decreasing trend in certain temperature intervals [8,9], but is not in agreement with some other experimental studies.…”

“…[12] 0.75 [8] 0.69 [9] 0.740 0.706 0.684 0.686 [6] 0.500 b [13] 1 c [62] 0.479 b [63] 0.514 b 0.493 b a The numbers given are for calculation of D and P, but χ am = 1 was used for calculation of S, since crystallinity was already accounted for in the reference. b Not given explicitly in reference, but calculated from density.…”

“…It is evident from Figure 3 that including these atomic charges has a marginal effect on the PE density. Other studies are shown in grey and refers to: another simulation study ( ) [14], and experimental studies ( ) [4,5], ( ) [60], ( ) [61], ( ) [12] , ( ) [8], ( ) [9], ( ) [6], ( ) [13] and ( ) [62]. The experimental data are converted using equation 10 and the factors in Table 1 Solubility Figure 4 shows simulated and experimental solubility coefficients for oxygen and water in PE at 1 atm and temperatures from 278 K to 308 K. showing that the inclusion of atomic charges in the force field does not significantly affect the solubility coefficients.…”

“…Experimental studies provide valuable understanding of the macroscopic [4][5][6][7][8][9] and microscopic [10,11] properties of polymers and their transport properties. Michaels and co-workers [4,5] found that there is a slight increase in the solubility of oxygen in polyethylene between 285 and 315 K, and that a further increase in temperature results in a far larger solubility.…”

“…Experimental studies of diffusion of oxygen in PE [8,9,12] typically show an increase in diffusion coefficient with increasing temperature. These experiments have been conducted from 277 to 335 K, and the diffusion coefficients are ~10 -8 -10 -6 cm 2 s -1 .…”