The effects of gamma-irradiation on compositional changes in plastic packaging films

Sterilization of packaging materials for pharmaceutical or food products wi th ionizing ir irradiation can cause chemical and physical changes in polym er materials. The effects of gamma-irradiation on the formation of solvent extractable radiolysis products of six flexible packaging materia is for fo r foodstuffs and/or pharmaceutical applications were studied after treatmen t in a Co-60-irradiation plant. The polymer materials polyethylene, polypvo ptylene, poly(ethylene terephthalate), polyamide, polystyrene and poly(viny l chloride) were investigated after treating with an irradiation nose of 44 kGy. The compositional changes in solvent extractable radiolysis products of each packaging material were quantified. In most cases the radiolysis yl products formed could be identified using GC/MS. The polyolefine materials (PE and PP) showed an increase of low volatile co mpounds after irradiation due to an oxidative decomposition of the polymer and typical polymer substances like oligomers and additives. Other packagin g materials such as PET, PA and PS did not significantly change their amoun t Of solvent extractable compounds after irradiation with 44 kGy The PVC pa ckaging material used in this study was not resistant to irradiation treatm ent at all. Because of the release of HCl during irradiation a large amount of volatile substances could be extracted from PVC sheet. For consumer pro tection and also to meet general food packaging legislative requirements fo r irradiated packaging materials, it is necessary to evaluate the compositi onal changes in the polymers during irradiation, especially for irradiated polyolefines and PVC. Most attention should be paid to low volatile radioly sis products which are the most likely to migrate into a foodstuff or a pha rmaceutical product. Copyright (C) 1999 John Wiley & Sons, Ltd.