Radiation Resistance of Multilayer Films by Instrumented Impact Testing

Abstract

This chapter presents the development of a radiation resistant multi-layer film with the aid of an instrumented impact tester where material degradation can be quantified. It is imperative to develop a rapid testing method where physical degradation of film properties after radiation sterilization can be assessed. Since many of the shipping protocols involve winter shipping simulation, where temperatures approaching freezing are frequently encountered, an ASTM low temperature condition would be required. To confirm that long lived free radicals do play a significant role in the post irradiation PP degradation, three films were evaluated by impact testing at 5°C to assess the physical degradation after radiation sterilization. The films were selected to examine the relationship of a PP layer when modified with the addition of elastomeric impact modifiers. The morphologies and impact energies were examined. It was found that the addition of a PP layer, contributing as little as 10% to the overall thickness of a film, reduces the impact energy significantly and changes the morphology from a ductile fracture to a brittle fracture.