Project title: Towards a Predictive Model of Elastomer Materials

Supervisors: Arash Mostofi and Adrian Sutton

Collaborators: John Stevens, Baker Hughes

Project description:

Elastomers are a class of versatile materials widely used in industry. This project focuses on the use of elastomers as seals for mechanical components in the oil industry. Two of the main elastomers used in seals are nitrile butadiene rubber (NBR) and hydrogenated nitrile butadiene rubber (HNBR). The project has a direct and important impact on current technology since failure of seals leads to significant costs for companies. It is found that in
down-hole conditions for long times, these seals are permeable to chemicals such as CO2. When the drill string is brought back to surface for maintenance, the seals can undergo so-called “explosive decompression” in which the rapid expansion of gas dissolved or trapped inside the elastomer leads to mechanical rupture of the seal.

Baker Hughes – a leading company in oil and gas services – sponsors two TSM studentships to investigate the phenomena that lead to this costly failure. The aim of one student, Musab Khawaja, is to look into the absorption and transport properties of gases inside elastomers while my focus is on the mechanical properties. My starting point was the development of a new atomistic model of HNBR to complement the model for NBR, based on the OPLS-AA force-field, that is being used by Musab.

The project started with the study of bulk properties of the base polymer using a fully atomistic approach. However, the mechanical responses of a real elastomer are massively affected by the presence of fillers (such as silica or carbon black nanoparticles) which are beyond the time and length scale of a fully atomistic approach. Therefore, I am focusing my research on the development of a course-grain model in order to study the problem.