Gas permeability and DSC characteristics of polymers used in food packaging

The work is an experimental study of gas permeability and DSC characterisat ion of polymers used in food packaging. For this purpose polyethylene (0.03 and 0.1 mm), polypropylene (0.03 mm), and coextruded polypropylene (0.03 m m) were studied. The permeabilities of polymers to oxygen and nitrogen were measured at different temperatures using the manometric method. Permeabili ty, diffusion and solubility constants were also calculated while temperatu res and enthalpies of the phase change were determined by the DSC method. P ermeability of gases increases with temperature for all investigated sample s. Permeability data of all investigated samples showed good agreement with the Arrhenius equation. Upon temperature increase starting from 40 degrees C all samples undergo phase change in the temperature range from 107 degree sC to 173 degreesC with enthalpies in the range of 40 to 85 J g(-1). Experi ments where simulated conditions of food sterilisation were used as well as exposition to radiation in a microwave oven showed negligible changes in D SC indicating structural stability of the polymers. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.