A comprehensive review of hydrogen-induced swelling in rubber composites

Rubber sealing components are crucial and highly vulnerable parts in high-pressure hydrogen systems, which represent the weakest link where seal failure becomes the crucial factor limiting the increase in working pressure of hydrogen energy equipment. Prolonged exposure to hydrogen environments causes rubber materials to experience volumetric expansion, resulting in decreased sealing reliability and durability, posing significant safety risks. This review focuses on rubber sealing materials used in hydrogen energy equipment. Firstly, the current mainstream mechanisms of hydrogen-induced swelling are introduced, covering the hydrogen exposure and decompression stages. Subsequently, the impact of hydrogen-induced swelling on the micromorphology damage, mechanical performance deterioration and sealing performance reduction of rubber is elucidated. Furthermore, the primary influencing factors of rubber hydrogen-induced swelling are explored and summarized. Based on the analysis of the current state of researches, several recommendations are proposed for the study of hydrogen-induced swelling of rubber sealing materials, including broadening the influencing factors and constructing the correlations between hydrogen-induced swelling and other damages such as frictional wear to contributing the safe application of rubber seal in high-pressure hydrogen systems.