Transport properties of multilayer active PET films with different layers configuration

The integration of active scavengers inside polymeric films is still facing technological difficulties related to material storage and handling, because of the rapid exhaustion of the scavenger due to the reduced thickness involved. Therefore, the development of multilayer active structures and the optimization of active and inert layers configuration represent crucial points to achieve the best performance. In this article, the effect of different layouts on the transport properties of multilayer active PET films is investigated. Symmetrical, “IAI” films were produced by means of cast co-extrusion process, inserting the active layer (A), containing the oxygen scavenger, between two inert layers (I). Four different layouts were obtained, combining two thicknesses for the active layer and two for the inert layers. Oxygen absorption measurements pointed out the effectiveness of the inert layers in prolonging the scavenging activity of the active phase, controlling the oxygen diffusive flux through the core layer. The results highlighted the impact of the multilayer films configuration on the scavenging parameters (initial oxygen scavenging rate, exhaustion time, amount of oxygen absorbed per unit surface and scavenging capacity), the possibility to discriminate the individual contributions of active and inert layers and the good reproducibility of the films scavenging performance. Furthermore, results revealed the effect of the oxygen scavenger phase on PET morphology and functional properties, regarding the crystallization process, the oxygen permeability and tensile parameters.