Physical, Mechanical, and Thermal Characterization of the Elastomer Response to High-Pressure CO2 for Use in Carbon Capture and Storage Applications

Abstract

CO₂ transport efficiency is vital for the success of carbon capture, utilization, and storage (CCUS) which is considered one of the most viable solutions to limit CO₂ release in the atmosphere, aiming to reach net-zero CO₂ emissions. To increase transport efficiency, CO₂ must be compressed and transported as a liquid or supercritical fluid, conditions that might affect the performance of the materials employed. In fact, polymers may absorb CO₂ molecules during their handling via pipelines and ships and this can lead to plasticization and the risk of rapid gas decompression (RGD) damage when the CO₂ pressure is released. In this concern, elastomers comprise only a small portion of the CCS value chain because they are mainly used as seals and gaskets; however, they are essential elements for controlling leakage. This work presents the results of a comprehensive experimental characterization of high-pressure CO₂ compatibility in common elastomers, such as ethylene propylene diene monomer (EPDM), natural rubber (NR), and butyl rubber (IIR), via thermal, mechanical, and transient-sorption experiments. From the results obtained, we saw that CO₂ solubility is always lower than 0.09 g_CO2/g_pol for all materials, while permeability reaches values higher that 100 Barrer at 45 °C for EPDM and NR. The role of reinforcing fillers incorporated into the polymer matrix has been also analyzed with a focus on evaluating their influence on mechanical properties and CO₂ transport properties. In this concern, swelling decreases from 400 to 70% from NR to EPDM, as the filler content increases, suggesting a positive interaction between the two phases. The extent of the analysis has been then upgraded by performing a modeling description of the results through the use of a thermodynamic equation of state (EoS) approach, thanks to which the polymer–penetrant interaction can be predicted in a wider range of pressure and temperature, down to cryogenic environments, as the one required for the CCS transport chain.