Hydrogen permeability of reinforced polyamide 12 composites modified with carbon nanotubes for barrier lining applications in pipelines and storage tanks

Polyamide 12 (PA12) nanocomposites reinforced with carbon nanotubes (CNTs) functionalized using Fe 2 O 3 , CuO, MoO 3 , and La 2 O 3 were developed to enhance hydrogen barrier performance. CNTs were incorporated at loadings of 0.0625–1 wt% into the PA12 matrix. FTIR analysis confirmed successful surface functionalization and improved dispersion, while mechanical and thermal characterization revealed strong polymer–CNT interfacial interactions, increased chain organization, and enhanced structural stability. Hydrogen transport behavior was quantified through diffusion (D), solubility (S), and permeability (Pe) coefficients, complemented by temperature-dependent activation analysis. The PA12/CNT–Fe 2 O 3 system demonstrated the most pronounced barrier effect, achieving a permeability coefficient of 0.22 × 10 −12 mol m −1 s −1 ·MPa −1 at 0.5 wt%, corresponding to an approximately 75-fold reduction relative to neat PA12. At 1 wt% loading, measurable hydrogen transport was effectively suppressed, attributed to homogeneous CNT dispersion, strong interfacial adhesion, reduced free volume, and increased crystallinity. These lightweight nanocomposites show strong potential for hydrogen storage and transport applications. • Hydrogen dissolution and diffusion in PA12 and modified PA12 were experimentally investigated. • CNTs combined with metal oxide oxidants significantly improve hydrogen barrier performance of PA12 membranes. • Strong polymer–CNTs interactions improve mechanical strength and thermal stability. • PA12/CNTs–Fe 2 O 3 identified as a promising hydrogen-resistant lightweight composite.