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Title: Effects of the addition of biopolymer additives on the foam stability of a commercial detergent
Author: Kakoulli, Antonia
ISNI:       0000 0004 2717 6321
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2011
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Surfactants, the main ingredient of detergent formulations, have the ability to adsorb at air/water interfaces due to their amphiphilic nature. Surfactants can, therefore, be used as excellent foam stabilising agents in several systems, eliminating or preventing major destabilisation phenomena including drainage, coalescence and disproportionation. In this project the addition of a small concentration of surface active or non- surface active components to the surfactant-stabilised system; has been studied in relation to their ability of improving the foam stability of the system. Several additives have been examined as .to their ability to act as effective foam stabilizers. These included surface active proteins, polymers and surface and non-surface active particles. Probably the most effective foam stabilising material was a particle material formed after the complexation of Ethylcellulose with Cellulose. This complex, along with other additives that showed a modest improvement on the foam stability of the surfactant stabilised system, has been tested on their ability of resisting to bubble coalescence, disproportionation and drainage phenomena. Most of the tests have been completed using equipment specially designed at the workshop of the School of Food Science and Nutrition, University of Leeds. The surface activity of the surfactant system on its own and in the presence of the stabilising additives was measured in relation to the surface tension and the surface viscoelasticity properties of the systems in order to determine the mechanism of action of these stabilising additives. It has been shown that the possible mechanism of action is one that the particles are adsorbing at the interface acting synergistically with the surfactant and effectively enhance the foam stability of the system. Another possible way of stabilising could be that the particles are collected in the plateau borders and this slows down the liquid drainage and therefore the thinning and rupture of the lamellae. Confocal Laser Scanning Microscopy~ (CLSM) was used to exarrune the structure of the EC-C complex and explore how it is adsorbed at the interface in order to stabilise the bubbles on its own and at the presence of the anionic surfactant. As it has been concluded the particles are probably adsorbed at the bubble interface and even though the surfactant predominates at the interface the appearance of a certain concentration of particles can be seen through the confocal images, indicating that the complex is strongly adsorbed at the interface.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available