engleski

Effect of External Parameters on Barrier Characteristics of Polyethylene Film for Food Packaging,

This work shows how the permeability of gases depends on the temperature conditions as well as on the penetrant size and nature. Gas (O2, N2, and CO2) permeability (using manometric method, GDP-C Brugger instrument) of polyethylene (PE, thickness 0.05mm) is determined at different temperatures (from 4 º C to 60 º C). The permeance of the PE film increased with temperature increase. This was especially noticed for oxygen permeability (5150 cm3m-2d-1bar-1 at 40 º C and 15000 cm3m-2d-1bar-1 at 60 º C). Gas solubility also increases with temperature increase. More condensable and vapours gases, as CO2, shows a decrease of solubility with a temperature increase. It is due to the nature of the gas and the heat of solution that changes above the critical temperature. At 40 º C carbon dioxide solubility is the highest (0.0646 mLcm-3bar-1) followed by nitrogen (0.0548 mLcm-3bar-1) and oxygen (0.0177 mLcm-3bar-1). Although the gas diffusivity is between 10-7 and 10-6 cm2 s-1 for all gases analyzed, there are some differences between gases. For example at the room temperature (20 º C), the highest value shows oxygen (3.66x10-6 cm2s-1) followed by nitrogen (1.73x10-6 cm2s-1) and carbon dioxide (1.34x10-6 cm2s-1). As the N2 is as molecule the smallest one, it would be expected to have the highest value, but because of it’ s rather sluggishness it follows the oxygen.

Barrier Characteristics; Polyethylene Film; Food Packaging

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