Mechanical and thermal properties of commercial multilayer flexible plastic packaging materials irradiated with electron beam

The effects of electron-beam irradiation on mechanical and thermal properties were studied for two commercial multilayer structures of flexible food packaging. Both the laminated poly(ethylene terephthalate) (PET)/ low-density polyethylene (LDPE) and the coextruded LDPE/polyamide(PA)/LDPE structures were irradiated up to 120 kGy using a 1.5 MeV electron beam accelerator, at room temperature in the presence of air. Mechanical properties showed significant changes (p < 0.05), specially in sealability that was severely affected. Changes in mechanical properties were discussed in relation to the eight day and the six month period after irradiation. In addition, the DSC analysis six months after treatment showed that the fusion enthalpy of the PET/LDPE structure components increase for the LDPE from 10 kGy and decrease for the PET up to 120 kGy (p < 0.05). On the other hand, the LDPE/PA6/ LDPE presented increase in the LDPE and PA up to 120 kGy, except for LDPE at 10 and 15 kGy and PA at 5 kGy doses (p < 0.05). The effects of irradiation were less severe for the LDPE/PA6/LDPE than for the PET/LDPE. The electron-beam irradiation did not show advantageous results that could be of interest for commercial applications for the film industry, but brings important information about the packaging behavior for food producers who may decide to use irradiation as a form of cold pasteurization of their packed products.