Adhesion dynamics and interfacial behavior at room and high temperatures of ethylene vinyl alcohol/polyethylene-grafted maleic anhydride composite multilayer films obtained by co-extrusion

This work investigates the adhesion dynamics and interfacial behavior of ethylene vinyl alcohol (EVOH) and a commercial tie layer based on polyethylene-grafted maleic anhydride (PE-g-MA) films, manufactured through a multilayer co-extrusion process. The interfacial morphology is significantly influenced by the co-extrusion parameters and the cooling conditions. Moreover, increasing the co-extrusion temperature leads to an increase in interface thickness and induces greater entanglement, thereby enhancing adhesion. Additionally, water quenching caused the interdiffusion of the adjacent polymers across the interface to freeze and, in turn, resulted in a strong adhesion between EVOH and the tie layer. The corresponding failure mode is predominantly cohesive, particularly at elevated temperatures (60 °C and 80 °C), where we observed a 250 % improvement in the peel strength. Conversely, air cooling (slow) yielded adhesive failures irrespective of the peel test temperature. This study demonstrates the importance of understanding the process and the interfacial behavior that drives the adhesion mechanism between EVOH and PE-g-MA at room and high temperatures.