Polymer Materials for CO₂ Transport Applications

This thesis investigates the suitability of elastomeric materials for CO₂ transport applications within Carbon Capture and Storage (CCS) infrastructure by examining their thermal, mechanical, and structural responses to CO₂ exposure. The ability of these materials to maintain their performance under relevant CO₂ transport conditions is essential for ensuring operational reliability. While elastomers are widely used in sealing applications due to their flexibility, resilience, and chemical resistance, their interaction with CO₂ can result in plasticization, swelling, and irreversible alterations in their physical and mechanical properties. This thesis systematically evaluates the effects of CO₂ exposure on different elastomer systems, identifying key parameters that influence their behavior in CCS environments. Article 1 focuses on Ethylene Propylene Diene Monomer (EPDM) elastomers, examining the influence of crosslinking density and carbon black content on CO₂ uptake, permeability, diffusion behavior, and mechanical performance. To assess CO₂ transport properties, permeation tests using the constant volume and variable pressure method are conducted, while differential scanning calorimetry (DSC) and tensile testing provide insights into the thermal and mechanical responses of the materials. This study evaluates how material parameters impact the behavior of EPDM compounds in CO₂ environments, offering a detailed understanding of their suitability for CCS transport applications. Article 2 examines fluoroelastomers (FKMs), assessing the effects of fluorine content and carbon black loading on CO₂-induced plasticization, compression set, and mechanical properties. Given the widespread use of FKMs in high-performance sealing applications, this study evaluates their structural integrity using wide-angle X-ray scattering (WAXS), along with physical and mechanical performance under relevant CO₂ transport conditions. Article 3 investigates poly(epichlorohydrin-co-ethylene oxide-co-allyl glycidyl ether) (GECO) elastomers, focusing on how dual-filler systems, comprising carbon black (CB) and talc, differ from conventional CB filler alone in influencing CO₂ uptake, desorption kinetics, and structural stability. Further structural characterization using WAXS and Fourier-transform infrared spectroscopy (FTIR) is conducted to analyze structural changes, while scanning electron microscopy (SEM) examines surface morphology alterations following rapid gas decompression (RGD). Article 4 investigates EPDM, Natural Rubber (NR), and Isobutylene Isoprene Rubber (IIR), focusing on their thermal, mechanical, and transport behavior under high-pressure CO₂ exposure. Experimental methods include DSC, TGA, dilatometry, DMA, and gas sorption measurements. In addition, solubility and permeability are modeled using the Sanchez–Lacombe lattice fluid equation of state and the standard transport model in collaboration with research partners. The results show that EPDM exhibits low solubility and stable mechanical properties, while NR and IIR show more pronounced reductions in modulus during CO₂ exposure. IIR also displays blistering after decompression, indicating reduced mechanical integrity under rapid depressurization conditions. By integrating these studies, this thesis provides a comprehensive evaluation of different elastomers considered as potential materials for CO₂ transport applications due to their unique combination of properties. The findings contribute to a better understanding of how material parameters in compound formulations affect elastomer performance under CO₂ transport conditions, providing valuable criteria for material selection and optimization in CCS infrastructure.