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Stability of block copolymer surfactant-based emulsions in the presence of a salt
Dissertation (MSc (Applied Science: Chemical Technology))--University of Pretoria, 2020.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2021
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| _version_ | 1867613664382550016 |
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| access_status_str | Open Access |
| author2 | Focke, Walter Wilhelm |
| author_browse | Focke, Walter Wilhelm |
| author_facet | Focke, Walter Wilhelm |
| collection | Thesis |
| dc_rights_str_mv | © 2020 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc (Applied Science: Chemical Technology))--University of Pretoria, 2020. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/79251 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:39:44.581Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/79251 Stability of block copolymer surfactant-based emulsions in the presence of a salt Focke, Walter Wilhelm u14333733@tuks.co.za Du Toit, Elizabeth Louisa Kabong, Mwamb Alain UCTD Micelles interfacial tension emulsions particle size distribution Ostwald ripening coalescence Engineering, built environment and information technology theses SDG-06 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 Dissertation (MSc (Applied Science: Chemical Technology))--University of Pretoria, 2020. This project deals with the mixed micellar and interfacial properties of mixtures of three surfactants [sodium dodecyl sulphate (SDS), cetyltrimethylammonium bromide (CTAB), and tetraethylene glycol monododecyl ether (C12E4)] with ABA symmetrical triblock copolymer (Pluronic F127), which has many industrial applications. Evidence of F127 micellisation and interaction with surfactants in the aqueous phase is inferred through interfacial tension measurements. The solution containing diluted monomeric F127 showed complex formation with surfactants before the latter self-aggregate as pure micelles. The simultaneous presence of ionic surfactants and micellar F127 in solutions displayed a decrease of interfacial activity and led to the conclusion of F127 micelles disruption. C12E4 was found to interact differently with micellar F127 in forming mixed micelles, and no loss of interfacial activity was recorded. This “association-dissociation” behaviour of F127 and surfactants was leveraged to understand the stability of mineral oil in water emulsions formulated with them in the presence of sodium phosphate (Na3PO4). The mechanisms of emulsions breakdown were found to rely on aggregation behaviour and complex structure of F127 and surfactants mixtures in solution. Laser diffraction showed that unlike SDS and CTAB, mixed-emulsifier systems containing C12E4 are stable to both flocculation, Ostwald ripening and coalescence. Due to electrostatic repulsion between its head group and F127 hydrophilic block, and also because of the combined effect of Ostwald ripening and coalescence, CTAB emulsifier containing systems displayed quicker instability than SDS. SDS containing systems showed a progressive shifting of droplets size distributions to bimodality as SDS concentration was increased and heat exposure pursued, revealing the activity of two distinct population of droplets in the emulsions. More insight on the mechanisms underlying the stability of the three mixed emulsifier systems was gained in performing optical microscopy and rheology measurements; the results were found to be consistent with particle size distribution. mi2026 Chemical Engineering MSc (Applied Science: Chemical Technology) Unrestricted SDG-06: Clean water and sanitation SDG-09: Industry, innovation and infrastructure SDG-12: Responsible consumption and production 2021-04-06T07:22:29Z 2021-04-06T07:22:29Z 2020/05/05 2020 Dissertation Kabong, MA 2020, Stability of block copolymer surfactant-based emulsions in the presence of a salt, MSc Dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/79251> A2020 http://hdl.handle.net/2263/79251 en © 2020 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | UCTD Micelles interfacial tension emulsions particle size distribution Ostwald ripening coalescence Engineering, built environment and information technology theses SDG-06 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 Stability of block copolymer surfactant-based emulsions in the presence of a salt |
| title | Stability of block copolymer surfactant-based emulsions in the presence of a salt |
| title_full | Stability of block copolymer surfactant-based emulsions in the presence of a salt |
| title_fullStr | Stability of block copolymer surfactant-based emulsions in the presence of a salt |
| title_full_unstemmed | Stability of block copolymer surfactant-based emulsions in the presence of a salt |
| title_short | Stability of block copolymer surfactant-based emulsions in the presence of a salt |
| title_sort | stability of block copolymer surfactant based emulsions in the presence of a salt |
| topic | UCTD Micelles interfacial tension emulsions particle size distribution Ostwald ripening coalescence Engineering, built environment and information technology theses SDG-06 Engineering, built environment and information technology theses SDG-09 Engineering, built environment and information technology theses SDG-12 |
| url | http://hdl.handle.net/2263/79251 |