A polyamide and polyethylene multilayer composite with enhanced barrier and mechanical properties at high temperature†

An advanced multilayer thermoplastic composite, composed of Polyethylene of Raised Temperature (PERT), Polyamide 12 (PA12), and Maleic Anhydride Grafted Polyethylene (MA), has been developed for high-temperature, high-pressure applications. An adhesive layer consisting of 35–60–5 wt% PERT-PA12-MA (Blend), has been tailored to optimize adhesive strength between PERT and PA12 layers. The developed three-layer composite (Trilayer) demonstrated exceptional water vapor and CO₂ barrier properties by incorporating PERT as a water transmission retarder and PA12 as a CO₂ diffusion retarder. At 82 °C, the water vapor transmission rate and CO₂ permeability of Trilayer samples were 58%, and 31% lower than those of the Blend, respectively. The Trilayer samples exhibited an average Young's modulus that was 17% higher than that of the Blend, while the yield stress was similar to the Blend. In terms of creep resistance, the Trilayer samples showed a 29% and 40% reduction in tensile creep strain and creep rate, respectively, compared to the Blend. Additionally, the Trilayer samples achieved 48% and 39% decreases in flexural creep strain and creep rate, respectively, in the flexural creep test. The Trilayer also exhibited a 56% decrease in deformation under drop-weight impact and a 14% improved impact absorption compared to the Blend. The overall performance of the multi-layer thermoplastic composite made from PERT and PA12 constituents was significantly enhanced, aligning with the carbon footprint reduction initiative to substitute thermoset, metal, and other traditional materials.