High-Temperature Multilayer Composite Films of Polyethylene/Ethylene Vinyl Alcohol with Enhanced Flexural Moduli and Gas Barrier Properties

Ethylene Vinyl Alcohol (EVOH) exhibits superior barrier properties to carbon dioxide and methane with intrinsic brittleness, while Polyethylene (PE) possesses a remarkable moisture barrier with high ductility. It is hypothesized that multilayer composites of PE and EVOH could offer both exceptional barriers to all greenhouse gases as well as high toughness. In the present study, hybrid multilayers composed of Polyethylene of Raised Temperature (PE-RT), Polyethylene grafted Maleic Anhydride (PE-g-MA), and EVOH were fabricated in different configurations of two to five layers. The static flexural modulus of the 5-Layer (5L) film was measured to be 80% of the single-layer EVOH and 16.8% higher than the single-layer PE-RT. The loss factor of the 5L was obtained nearly equal or slightly higher than PE-RT over the measured temperature range of 30 to 90 °C, suggesting improved damping. The formation of hydrogen bonds at the interface of EVOH and PE-g-MA significantly limited the diffusion of water vapor molecules, resulting in the water vapor barrier performance of 5L film at 82 °C outperforming the predicted value using inverse additivity rule by 45.8%. Formation of hydrogen bonding at the interface of EVOH and PE-g-MA significantly limited the diffusion of water vapor molecules. A full microscopic and chemical composition analysis of interlayers was performed to reveal the underlying connection between the structure, property, and morphology. The classical lamination theory was successfully applied and validated for predicting the dynamic properties, which could be further used for design optimization of such multilayers. The performance of the proposed 5-layer symmetric structure confirms its potential for high-temperature–high-pressure applications.