Evaluation of multilayer film stability by Raman spectroscopy after gamma-irradiation sterilization process

Polymers such as polyethylene (PE) and ethylene vinyl alcohol (EVOH) are primary constituents of single use plastic systems in the biopharmaceutical and biotechnology industries. These devices are sterilized by gamma-irradiation prior to be used, the usual dose being between 25 and 45 kGy. Optical spectroscopies are of great interest for chemical analysis and are used to obtain information on the composition of materials such as polymers. Raman spectroscopy provides information on the fundamental vibrations of molecules, using excitation in the visible wavelength range. The purpose of this study is to unveil the impact of gamma-sterilization on polymers in industry-like experimental conditions. Cross-sections of films are analyzed before and after sterilization using different radiation doses: their compositions and chemical evolution of the material are examined using micro-Raman spectroscopy. As the chemical composition of the layers is complex, due to the presence of additive compounds, there is considerable overlap between the spectral data. In this case, the use of spectral curve resolution chemometric methods is unique for unravelling the complex identification of the layers and to study the degree of chemical modifications.