Experimental determination of the structure and performance of organic friction modifiers in solution and in tribo-contacts
Lead Research Organisation:
University of Cambridge
Department Name: Chemical Engineering and Biotechnology
Abstract
The PhD will focus on using developing/ optimising the bespoke-built tribo rig for in-situ neutron reflection studies of additive structure at the solid-liquid interface, with changes in load/ speed to produce the different trobological contacts encountered in the Stribeck Curve. Experiments will be performed in a semi-dynamic mode, investigating the structures found in contacts in real-time. Experimental results obtained (for both organic friction modifiers and in combination with other additives) will be simulated by a group at Edinburgh University to provide a mechanistic understanding of the processes by which organic friction modifiers function both in solution and in forming films at the solid-liquid interface.
People |
ORCID iD |
| Alexander Routh (Primary Supervisor) | |
| Alexander Armstrong (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509620/1 | 01/10/2016 | 30/09/2022 | |||
| 1943259 | Studentship | EP/N509620/1 | 01/10/2017 | 30/09/2021 | Alexander Armstrong |
| Description | This project focuses on understanding how Organic Friction Modifiers (OFMs) reduce friction between rubbing metal surfaces. The main techniques used in this project are neutron and x-ray reflectivity (NR and XRR respectively) which can resolve the structures of extremely thin films on surfaces. By using these techniques with a novel tribometer rig, we can study how OFM structures at these metal surfaces changes with shear. This work has allowed us to gain expertise in both NR and XRR, which are highly specialised techniques that require access to neutron and x-ray beamlines, specialised equipment & expensive chemicals. The NR and XRR experiments we have conducted so far with the novel tribometer rig have proven that it is a suitable environment for both techniques, provided it is used in non-contact mode (lower shear rates than initially planned for the tribometer). However. there are subtleties that are inherent with the use of the tribometer on neutron and x-ray reflectometers. Therefore, we have devoted a considerable amount of time to the development of suitable models to analyse the NR and XRR reflection data. Final models that match the data have been derived and have shown that standard reflectivity models used in the literature are not sufficient to describe the complex environment in the tribometer. The models suggest glycerol monooleate (GMO - an OFM) adsorbs at the iron oxide/dodecane interface to form thin layers under shear rates of up to 700 per second, where shear rates up to this value do not seem to have an affect on the structure of GMO. As an aside, we discovered that GMO adsorbs at the iron oxide/dodecane interface to form a weakly adsorbed surface film. As the concentration of GMO increases, the film thickness increases up until a maximum is reached. We have also found that when water is present in the solution of GMO in oily media, water is present in the surface film formed by GMO, suggesting that the structure at the interface is not a simple monolayer of GMO at the interface. Simulations of the structure at the interface, carried out by collaborators at the University of Edinburgh, also indicate that the GMO structure at the iron oxide-dodecane interface is not a simple monolayer. Crucially, when this structure is modelled in a reflectivity profile, it matches the experimental data very well, suggesting this model is physically consistent with experimental results and gives weight to the argument against a simple monolayer structure. |
| Exploitation Route | We have developed a strong understanding of how a future shear cell may need to be designed to accommodate usable neutron and x-ray reflectivity data. The understanding of reflection from certain complex geometries has been developed and can be used further in other user equipment. The basic understanding of how OFMs adsorb at the iron oxide/dodecane interface as a function of concentration and temperature has been explored. This work can be expanded upon by looking at mixtures of surfactants, and surfactants with more complex polar and non-polar groups. |
| Sectors | Chemicals,Energy |
| Description | Project is part of a CASE award with Infineum UK Ltd. The knowledge and findings of this project will aid Infineum in producing next-generation friction-reducing materials. This will aid in the reduction of carbon emissions from combustion engines around the globe. |
| First Year Of Impact | 2018 |
| Sector | Chemicals,Energy,Transport |
| Impact Types | Societal |
| Description | Multi-center consortium for study of Organic Friction Modifiers self assembly at bulk and interface. |
| Organisation | University of Bristol |
| Department | School of Chemistry |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Using our expertise in neutron reflectivity and in our novel tribometer rig, we supply the experimental data for the team at the University of Edinburgh to guide their simulations. We also provide the expertise to run reflectivity experiments with the novel surfactants produced by the team at the University of Bristol. |
| Collaborator Contribution | The team at the university of Edinburgh simulate our molecules to gain a clearer picture of how they behave in the bulk and at the iron oxide/dodecane interface. The team at the University of Bristol synthesise novel surfactants that we can study via neutron reflectometry experiments under static and sheared conditions. |
| Impact | Outputs are on-going. Neutron reflectivity experiment with the university of Bristol is planned in near-future. This collaboration is multi-disciplinary. The team at the University of Bristol bring, while the team at the University of Edinburgh are experts on the simulation of solutions between surfaces. |
| Start Year | 2018 |
| Description | Multi-center consortium for study of Organic Friction Modifiers self assembly at bulk and interface. |
| Organisation | University of Edinburgh |
| Department | School of Chemistry |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Using our expertise in neutron reflectivity and in our novel tribometer rig, we supply the experimental data for the team at the University of Edinburgh to guide their simulations. We also provide the expertise to run reflectivity experiments with the novel surfactants produced by the team at the University of Bristol. |
| Collaborator Contribution | The team at the university of Edinburgh simulate our molecules to gain a clearer picture of how they behave in the bulk and at the iron oxide/dodecane interface. The team at the University of Bristol synthesise novel surfactants that we can study via neutron reflectometry experiments under static and sheared conditions. |
| Impact | Outputs are on-going. Neutron reflectivity experiment with the university of Bristol is planned in near-future. This collaboration is multi-disciplinary. The team at the University of Bristol bring, while the team at the University of Edinburgh are experts on the simulation of solutions between surfaces. |
| Start Year | 2018 |
| Description | Talk at the Edwards Centre for Soft Matter |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Postgraduate students |
| Results and Impact | Talk given on my PhD project so far. Discussed our use of neutron reflectivity to study thin films at solid/liquid interfaces under static and sheared conditions with the tribometer, and the underlying theory to understanding the data we have collected so far. |
| Year(s) Of Engagement Activity | 2020 |