Hydrogen permeability of thermoplastic composites and liner systems for future mobility applications

High pressure hydrogen permeation tests were carried out and specific permeation rates of various thermoplastic matrix materials have been measured as well as of continuous fiber reinforced thermoplastic composites (PA6, PA12, PA410, PPA, PPS), considering non-crimp and crimp textile architectures. Furthermore, liners based on thermoplastic high barrier films made of EVOH were applied on PA6 composites and their effect on permeation rate were investigated. All samples were accompanied by pressure tightness tests and micrographs to determine manufacturing effects, microstructure, porosity and additional defects like microcracks. Experiments show that thermoplastic composites can reach low permeation rate as long as a damage-free microstructure is ensured. Furthermore, the influence of the matrix material can be assessed, whereby the influence of the textile architecture can only be roughly estimated and is considered to be small. EVOH layers show remarkable barrier properties and are easy to integrate into the composite structure.