Synergistic Enhancement of Mechanical, Thermal, and Hydrogen Barrier Properties of Nylon with PEI-GO-EVOH Nanocomposite Coatings

Hydrogen permeation is a major challenge in high-pressure gaseous hydrogen storage and transportation. In this study, a series of novel polyethylenimine-modified graphene oxide/polyethylene-vinyl alcohol (PEI-GO-EVOH) composites were prepared and coated on a nylon substrate for hydrogen barrier applications. Hydrophilic PEI was employed to modify graphene oxide, thereby promoting the uniform dispersion of PEI-GO within the EVOH matrix. Various characterization techniques were used to investigate how PEI-GO influences the morphology, thermal stability, mechanical properties, adhesion, hydrophilicity, and hydrogen barrier performance of the composite coatings. GO-EVOH composites were also prepared and characterized for comparison. Compared to pure EVOH and GO-EVOH, PEI-GO-EVOH composites exhibited enhanced thermal and mechanical stability, along with significantly improved hydrogen barrier properties. Hydrogen bonding between the components was proven to play a dominant role in these property improvements. At a PEI-GO content of 2 wt %, the hydrogen permeability of PEI-GO-EVOH coatings decreased by 48.4% and 42.9% compared to the bare nylon substrate and the GO-EVOH coating, respectively. When benchmarked against reported hydrogen barrier systems, the PEI-GO-EVOH coating achieves competitive performance with lower filler loading, confirming its potential as a suitable hydrogen barrier coating for nonmetallic pipelines and hydrogen storage containers.