Method for Measuring the Uptake and Diffusivity of Hydrogen Gas in Sulfur-Crosslinked Ethylene Propylene Diene Monomer Polymer Composites with Fillers Using Image Analysis Algorithm of Water Level

In hydrogen refueling stations, polymer O-rings are used for high-pressure hydrogen containers and transfer pipes to prevent gas leakage. A technology has been developed to measure the hydrogen uptake and diffusivity of the polymer materials used in these O-rings. The process involves charging the polymer material with hydrogen under a maximum pressure of 90 MPa, then depressurizing it. Afterward, the polymer is placed in a cylinder partially submerged in water. The pressure difference causes hydrogen gas to be released from the polymer material, resulting in a decrease in the water level in the cylinder, which corresponds to the increase in the volume of released hydrogen gas. To measure this volume change in real-time, a brightness analysis algorithm was developed to track the water level, which takes the form of a crescent shape inside the cylinder. This allows for precise tracking of the water level change. Using the real-time volume change data, the number of moles of released hydrogen gas is calculated based on the ideal gas law. This technology enables the evaluation of hydrogen uptake and diffusivity of polymer materials using a self-developed diffusivity analysis program. This technology was applied to evaluate hydrogen uptake and diffusivity in sulfur-crosslinked EPDM composites containing carbon black and silica fillers. The relationship between filler types and the hydrogen uptake/diffusivity of the EPDM composites was measured across a pressure range of 2 MPa to 90 MPa. The effects of fillers and pressure on hydrogen uptake and diffusivity were studied. Additionally, the correlation between the physical stability of the EPDM composites and their hydrogen uptake/diffusivity was investigated. A positive proportional relationship was found between the volume expansion of the EPDM composite and the hydrogen uptake/diffusivity, while a negative proportional relationship was observed between the polymer's density and its hydrogen uptake/diffusivity.Finally, the effectiveness of this technology was validated through uncertainty analysis of the charging amount and diffusion coefficient measurements, with all results falling within an uncertainty of 10%.