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Gas permeability of gamma-irradiated polyethylene and polypropylene films

Linear low density polyethylene (PE-LLD) and cast polypropylene (PPcast) films were irradiated by γ-irradiation. The total irradiation dose varied from 0 kGy (for nonirradiated samples) to 200 kGy. Oxygen transport was investigated by a manometric method and the structural changes were studied by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The results show that the γ-irradiation slightly reduces oxygen permeability coefficient in both films. The reduction was associated with an increase in crystallinity. DSC thermograms revealed a decrease in PPcast melting temperature with irradiation dose indicating higher degradation compared to polyethylene. The observed peak in FTIR spectra for both samples at 1716 cm-1 corresponds to the stretching of the carbonyl and carboxylic groups which arise from the reaction of oxygen with the free radicals produced in the polymer matrix as a result of irradiation.

gas permeability; polyethylene; polypropylene; gamma-irradiation; FTIR; DSC

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