Reducing ammonia permeance in poly(acrylonitrile‐co‐butadiene) (NBR)‐based elastomers

Abstract

AbstractAmmonia (NH3) has emerged as a sustainable future fuel for a low‐carbon future. Ideally, the transportation and storage of ammonia in re‐purposed natural gas networks will dramatically reduce the economic burden associated with converting to ammonia. However, the highly condensable nature and small kinetic diameter of the ammonia means that this fuel readily permeates through the polymer‐based elastomers and gaskets used in natural gas infrastructure. To mitigate this issue, three kinds of additives have been incorporated into the conventional natural gas elastomer poly(acrylonitrile‐co‐butadiene) (NBR) to reduce ammonia permeance. The first is based on increasing the basicity of the elastomer environment, the second provides chemical reactivity with ammonia to limit transport, and the third uses barrier additives to prevent diffusion. The mechanical properties of the modified elastomers; expressed as the tensile stress at yield and Young's modulus were studied. The creation of a basic environment through the addition of amines resulted in moderate changes in ammonia permeability, with up to 50% reduction of ammonia permeability observed from putrescine added NBR. Chemical additives lowered the permeability by up to 20% with limited impact on the tensile properties. The addition of 3% graphene oxide to NBR had the most significant decrease in ammonia permeability, 80%, but also produced a more rigid material. The investigation shows that ammonia permeability can be significantly reduced in NBR elastomers, through the addition of inexpensive additives in tailored strategies.