Effect of ionising irradiation on silver release from polyolefin/silver nanocomposite films into food simulants

Two types of nanocomposite films, polyethylene/silver (PE/Ag) and polypropylene/silver (PP/Ag), were prepared and characterised. Assessment of silver released under the effect of ionising irradiation was performed on the nanocomposite films. The release experiment was carried out by immersing the nanocomposite films in water, 3% acetic acid or 95% ethanol as food simulants and measuring the Ag release from nanocomposite films treated with and without gamma or electron beam irradiation at a dose of 10 kGy. In general, irradiation treatment increased the Ag release regardless of the type of polymer and food simulant. One reason could be radiation-induced metal oxidation at the surface which in turn promoted ion release into food simulants. The oxidising radicals produced by radiation in solution could be another factor speeding up metal oxidation and subsequent ion release. When comparisons were made between the two types of irradiation, greater Ag release into water and 3% acetic acid was observed after electron beam irradiation, while gamma irradiation was likely to induce greater Ag release into 95% ethanol. Such phenomena reveal the influence of different types of radiation on the solutions which in turn affect the Ag release.