Effects of MXD6 and MXD10 on the Toughness and Hydrogen Barrier Properties of PA6 / POE ‐ g ‐ MAH Blend for Type IV Hydrogen Storage Vessel Liners

Abstract

ABSTRACT Type IV hydrogen storage vessel liners demand balanced hydrogen barrier, toughness, and hygroscopicity. Semi‐aromatic nylons poly(m‐xylylene adipamide) (MXD6) and poly(m‐xylylene sebacamide) (MXD10) were introduced into PA6/POE‐g‐MAH (80/20, S80E20) by melt‐blending, yielding the PA6/POE‐g‐MAH/MXD6, and PA6/POE‐g‐MAH/MXD10 blends, respectively. With increasing MXD6 content, tensile and bending strengths and modulus all increase, whereas with MXD10 content they first rise and then fall. Impact strengths at 23°C and −30°C decrease yet remain far above neat PA6, and elongation at break declines sharply for the PA6/POE‐g‐MAH/MXD6 blends, but only mildly for the PA6/POE‐g‐MAH/MXD10 blends. At 20 wt%, PA6/POE‐g‐MAH/MXD6 (80/20/20, S80E20DS20) exhibits impact strengths of 66.2 kJ/m 2 (23°C) and 17.46 kJ/m 2 (−30°C) with an elongation at break of 72.49%, whereas PA6/POE‐g‐MAH/MXD10 (80/20/20, S80E20DT20) shows 54.66 and 21.53 kJ/m 2 with a substantially higher elongation of 181.29%. Hydrogen permeability coefficients of S80E20DS20 and S80E20DT20 are 3.89 × 10 −14 and 3.98 × 10 −14 cm 3 ·cm/(cm 2 ·s·Pa)—reductions of 11.99% and 9.95% over S80E20 blend (4.42 × 10 −14 ), yet above neat PA6 (2.82 × 10 −14 ). Both blends show lower hygroscopicity than neat PA6 and S80E20. Thus, S80E20DT20 offers substantially improved ductility, higher impact strength at −30°C, a still‐high impact strength at 23°C despite a reduction, and only marginally lower hydrogen barrier performance than S80E20DS20, meeting the hydrogen permeability requirement stipulated in GB/T 42612‐2023. This ternary blending strategy provides a promising route to high‐performance PA6 liners.