Experimental investigation of Rapid Gas Decompression in elastomers for the CO2 and H2 transportation infrastructure

Human activities have led to a significant increase in atmospheric carbon dioxide, contributing to global warming. In this context, Carbon Capture and Storage (CCS) represents a key technology for reducing carbon emissions, particularly when coupled with fossil fuel reforming for blue hydrogen production. The transportation of CO2 and H2 is thus a key in this energetic scenario, and the use of polymeric components and elastomers is really relevant to prevent metal corrosion and ensure leakage tightness. Since both CO2 and H2 are soluble in polymers, their absorption may alter the material properties of elastomers. Under the high-pressure conditions typical of transport infrastructures, elastomers are susceptible to rapid gas decompression (RGD), which can cause internal damage during depressurization. This thesis investigates the effects of CO2 and H2 on elastomer resistance under RGD, aiming to identify the structural and chemical characteristics required to preserve adequate operational performance. Three elastomer families were analyzed: fluorinated rubbers, EPDM rubbers, and one hydrogenated nitrile butadiene rubber. Within each family, samples differed in polymer structure, cross-linking density, and carbon black content, parameters known to influence mechanical resistance. All samples were subjected to a single decompression cycle, while undamaged specimens were further exposed to multiple RGD events. The best-performing elastomers were additionally characterized through tensile strength and hardness testing after decompression to assess compliance with operational requirements. Thermogravimetric analysis (TGA) was also conducted post-RGD to evaluate possible changes in thermal stability. For hydrogen-related RGD tests, permeation measurements were performed to determine transport properties and to assess whether the elastomers could experience RGD-related damage under pressurized H2.