Influence of Metal Supports on the Measurement of Hydrogen Permeation Properties of High Density Polyethylene

Abstract High-density polyethylene (HDPE) is a common material used for type IV hydrogen storage cylinders and non-metallic hydrogen pipelines. Its hydrogen permeability is a key fundamental property that determines its applicability in hydrogen-related fields. The accurate measurement of the hydrogen permeability of HDPE materials has always been a hot topic of interest in both academia and industry. Pressure difference method is commonly applied for measuring the hydrogen permeation properties of materials. Metal supports are used on the low-pressure side to prevent sample deformation, but their structure may affect the accuracy of hydrogen permeation measurements, as the presence of the metal support also acts as a certain barrier to hydrogen permeation. This study investigated the impact of the perforated metal support on the hydrogen permeation properties test of HDPE through theoretical analysis and experimental research. The results indicate that the existence of the perforated metal support alters the permeation distance and area, leading to underestimation of the hydrogen permeation parameters for HDPE, and the measured hydrogen permeation properties decrease as the pore area of the metal perforated support decreases. Furthermore, a correction formula for hydrogen permeation parameters influenced by the perforated support was derived by fitting a single exponential decay function. This study also proposes a correction method for the existing perforated support testing and calculation of hydrogen permeation parameters in HDPE. Specifically, the parameters P, D, and S measured without considering the barrier effect of the metal support can be corrected to obtain the true hydrogen permeation parameters P0, D0, and S0. This approach aims to enhance the accuracy of the hydrogen permeability coefficient measurement, which is crucial for the reliable assessment of HDPE materials in hydrogen storage applications.