Electro-rheological (ER) fluids, which are dispersions of solid particles in a non-conducting oil, have been studied for the first time at a molecular level using magnetic resonance spectroscopic techniques. The group of fluids on which measurements were first made was the already widely used lithium polymethacrylate dispersed in 20 cs silicone oil. The problems associated with this fluid such as high conductivity, relatively low viscosity changes, and settling out of the solid particles, led to fluids containing zeolites also to be investigated. Mechanical tests were performed on all these fluidsincluding static yield stresses measured at zero shear rate,and then a new electroviscometer was designed and built totest fluid performances in the shear rate range from 1.5 to 43.8 s and temperatures from +5 to +60 C.NMR relaxation measurements were used to study themobilities of the water and the ions in all these solids toinvestigate the relationship between these properties, and the performance of a solid as a constituent in an ER fluid. This is the first time that many of these systems have been studied in this way. ESR was used to study the motion of spin probe radicals in partially hydrated zeolites for the first time. The effect of an electric field on the motion of the spin probe inside a zeolite particle was measured and decreased motion was observed as the strength of the electric field wasincreased in those zeolites which showed a significant EReffect, while no effect on the probe motion was seen for those zeolites which constituted a weak ER fluid. The first saturation transfer ESR experiments have been performed on spin probes inside partially hydrated zeolites that previously had been out of the motional range of conventional CWESR, and the anisotropy of the probe motion has been highlighted.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:704456 |
| Date | January 1989 |
| Creators | Bailey, Phillip |
| Publisher | Royal Holloway, University of London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://repository.royalholloway.ac.uk/items/8a94b0c6-b9ba-45c5-a207-98d8a7552bee/1/ |
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