No description available.

This thesis is concerned with the interactions of oils with surfactants. The understanding of these interactions is important for a number of practical applications which include perfume delivery in fabric softeners. Both non-ionic surfactants, of the general formula H( CH2)n( OCH2CH2)m-OH, and lome surfactants, of the general formula CnH2n+lW(CH3)3Br were used in the study. Oils of varying polarity were investigated from non-polar alkane oils to moderately polar perfume oils.Initially, the work of adhesions of the perfume oils with water were studied to establish where these oils 'fitted-in' to a range of oils of varying polarity. It was found that the three perfume oils studied (linalool, cineole and eugenol) all exhibited adhesion properties which were fairly typical of moderately polar oils. In order to obtain the enthalpies and entropies of adhesion of the perfume oils with water the surface tensions and interfacial tensions with water were measured as a function of temperature. The enthalpy of adhesion for linalool with water is consistent with values obtained for the enthalpy of hydration of the hydroxyl group.The co-surfactant nature of the perfume oils was investigated by tension measurements of their adsorption to the heptane-water interface. Linalool and eugenol show reasonably high surface activity at this interface and could therefore be expected to act as cosurfactants in systems that contain conventional surfactants.The phase behaviour of the CgE5 + water + octane micro emulsion system was investigated to determine the effect of adding different concentrations of perfume oil on the size, shape and position of the three phase region. It was found that linalool reduces the size of this three phase region and also reduces the temperature at which the three phase region occurs. Although not conclusive, this behaviour suggests the system is approaching a triclitical point.It is of interest also to understand the adsorption of oils at planar surfactant mono layers and then attempt to relate the adsorption data to bulk phase solubilisation of the oils in micelles. The adsorption at a planar interface was attained by measuring the surface pressure of the oil at different activities. The surface concentration of the oils was then calculated from the Gibbs adsorption equation. By measuring these surface pressures as a function of activities at various temperatures, it was possible to derive the adsorption enthalpies and entropies with use of a form of the Van't Hoff equation. It was found that alkane adsorption increases with decreasing alkane chain length and the isotherms show a greater curvature upwards for the shorter chain length alkanes suggesting that the adsorption becomes more favourable as more alkane is added to the mixed alkane/surfactant film.Headspace analysis was employed to measure the solubilisation of oils in bulk surfactant solutions. The results obtained with this technique were preliminary although early indications suggest that more alkane oil is solubilised in bulk aggregates with curved monolayers than is adsorbed at planar monolayer interfaces. However, solubilisation of oil in bulk solutions may either be in the curved monolayer or they could form a 'core' of oil inside the aggregate.

Thesis (M.Sc. (Chemical Engineering)) -- University of Pretoria, 2007. / Includes bibliographical references.

Thesis (M.Sc.)(Chemistry)--University of Pretoria, 2004. / Summaries in English and Afrikaans. Includes bibliographical references.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: lubrication; rupture; journal bearings; Reynolds equation; thin films; cavitation. Includes bibliographical references (p. 72-76).

Thesis (M.S.)--Mechanical Engineering, Georgia Institute of Technology, 2005. / Jiri Janata, Committee Member ; Shreyes Melkote, Committee Member ; Steven Danyluk, Committee Chair. Includes bibliographical references.

Thesis (Ph. D.)--Columbia University, 1933. / Vita.

M.Sc. / It is estimated that there are approximately 6.9 million vehicles operating on South African roads, four million (58%) of which represent passenger cars. (Mbendi, 2002a). The number of vehicles operating on national roads increase annually. For motor vehicle engines to perform optimally, among other components, they require engine oil. Nationally in 2002, approximately 40 million litres of motor oil were sold at service station forecourts. For the same period, Gauteng motor oil sales exceeded 17.5 million litres while 76% of these sales occurred in Johannesburg (Maneveld, 2003b). When motor oil is poured into an engine there is always an amount of oil that remains in the container. In this study the author quantifies the amount of unused motor oil that is discarded into the environment via the containers that carry it and makes an assessment of the associated environmental implications. In the South African context, no documented data regarding this problem exists. Chapter one provides the background and motivation to the study, an explicit description of the problem being researched, objectives of the research, the study area and a brief description of the research methodology. This chapter defines the parameters within which the research took place. Chapter two briefly describes the South African oil and lubricants industry. It also focuses on lubricant manufacture, blending, composition, use and properties of lubricants. Chapter three details the research methodology and data collection procedures. This is followed by an analysis of the pilot and main study encompassing statistical interpretation and synthesis. Graphical and photographic illustrations are used. Conclusions were reached on the basis of factual information. Chapter four collates the information from previous chapters, which enables the author to make projections and quantify the amount of unused oil discarded into the environment. An assessment of the associated environmental implications is then determined. In the last chapter, limitations of the study are discussed. This is followed by concluding statements, proposals for further research and recommendations to address the research problem.

Master of Science

No description available.