Vervoort, Sylvie (2006) Behaviour of hydrogels swollen in polymer solutions under mechanical action. PhD thesis Sciences et Génie des Matériaux, ENSMP - CEMEF Centre de Mise en Forme des Matériaux, ENSMP.
Abstract
The behaviour of highly swollen polyelectrolyte gels containing linear polymer solutions submitted to mechanical stresses (shear, compression) was studied using rheo-optical tools in order to gain understanding in gel behaviour and to open the way towards the application of hydrogels in cosmetic applications. Shear stresses were imposed on isolated gel particles suspended in a silicone oil matrix. Different regimes were identified: at the lowest stresses, the particle only deforms, but less than a droplet of its solvent would do. Above a first threshold stress, release of some solvent is observed in the flow direction. The solvent tips stay attached to the particle. The solvent can be detached and dispersed into the matrix at stresses above a second critical stress. Release and ejection were also observed in the vorticity direction. Important volumes of solvent can be set free. The effects of particle size, degree of swelling, polymer solution concentration and interfacial tension were evaluated. The compression tests were executed with gel disks swollen at equilibrium in water or in a polymer solution and surrounded by air. The gel deforms and releases some solvent as soon as it undergoes some stress. The thermodynamical analysis of such system predicts that release is more important for weakly charged gels than for neutral-ones.
| Item Type: | PhD Thesis (PhD) |
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| Thesis Supervisor: | Budtova, Tatiana |
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| Date: | May 2006 |
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| Board of examiners: | Durand, Dominique and Moldenaers, Paula and Poncelet, Denis and Tranchant, Jean-François and Navard, Patrick |
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| Ecole Doctorale: | ED 364 SCIENCES FONDAMENTALES ET APPLIQUEES |
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| Discipline: | Sciences et Génie des Matériaux |
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| Collection (Fonds): | ENSMP |
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| Institution: | ENSMP |
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| Department: | ENSMP - CEMEF Centre de Mise en Forme des Matériaux |
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| Subjects: | 4. Materials Science, Mechanics and Mechanical Engineering |
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| Uncontrolled Keywords: | Hydrogel, Deformation, Controlled release, Rheo-optics, Simple shear flow, Compression, Hydrogel, Déformation, Relargage contrôlé, Rhéo-optique, Cisaillement simple, Compression |
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