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Physico-Chemical Characterisation and Molecular Modelling Study of Lubricant Dispersants.

Tomlinson, Angela. (1998) Physico-Chemical Characterisation and Molecular Modelling Study of Lubricant Dispersants. Doctoral thesis, University of Surrey (United Kingdom)..

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Abstract

Succinimide dispersants are used in engine oils to reduce aggregation of carbonaceous deposits arising from the combustion process. This thesis describes an experimental and molecular modelling investigation into the physical characteristics of these dispersants. An introduction to dispersants and key processes that possibly contribute to the dispersancy mechanism are presented in chapters one and two. A matrix of straight chain C8-C18 mono-, bis- and tris- model succinimide compounds with chemically variable headgroups were synthesised and a range of analytical techniques were used to characterise their interfacial and solution behaviour. This work is described in chapters three, four and five. Vapour pressure osmometry measurements revealed that the succinimides behave as typical amphiphilic oligomers in hydrophobic solvents with little association except for the mono- compounds. Langmuir trough experiments gave information on the physical arrangement of the molecules in a close-packed monolayer, demonstrating that packing on a surface is highly dependent on the size and shape of the headgroup and less so on chainlength. Ellipsometry performed on these molecules deposited onto silicon wafers showed that the C18 molecules formed good coverage close-packed Langmuir-Blodgett multi-layer films. The succinimides are extremely effective at adsorbing onto polar substrates, demonstrated in both the TLC and adsorption studies with activated carbon. Viscometry experiments with activated carbon suspensions have provided the basis for a laboratory scale dispersancy test. Computer simulations described in chapter six give supporting evidence for the succinimides affinity for polar moities on carbonaceous surfaces, and sensitivity of adsorption to chemical composition of the dispersant molecules and surface curvature. Chapter seven concludes by bringing together the results from the experimental and modelling studies presenting the main conclusions and suggesting topics for further research.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Tomlinson, Angela.
Date : 1998
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 1998.
Depositing User : EPrints Services
Date Deposited : 14 May 2020 14:56
Last Modified : 14 May 2020 15:07
URI: http://epubs.surrey.ac.uk/id/eprint/856798

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