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Thesis
Depolarized light scattering and rheology of hydrogels
Master of Science (M.S.), Drexel University
Jun 2008
DOI:
https://doi.org/10.17918/etd-2925
Abstract
The goal of this thesis was to design, develop and characterize a non-destructive method to assess the mechanical properties of clear hydrogels using information from the depolarized scattering of focused light. There are currently no published commercially available systems with the ability to monitor remotely the crosslinking density of hydrogel systems. This new system will allow for accurate in-process monitoring and process optimization without the loss of product. The optical system developed uses inexpensive off-the-shelf components and measures the relative intensity, a qualitative measure that is correlated to the crosslinking density of ionically (Ca²⁺) crosslinked alginate gels. The incident laser (685 nm wavelength) is vertically polarized while the scattered light is collected after having been horizontally polarized The crosslinked sections of hydrogels, are structures where the local index of refraction varies when observed from different directions, that is they exhibit optical anisotropy. polarized light scattering is a sensitive measurement method for the investigation of systems exhibiting local anisotropy, such as macromolecules and liquid crystals. The polarized light is scattered from both isotropic and anisotropic structures within the media, and by measuring the depolarized light, the contribution of the anisotropic structures can be separated and assessed. We have used as a model hydrogel system sodium alginate hydrogels crosslinked by Calcium ions (in the form of CaCl2). The scattered depolarized light intensity is related to a "flow index", a measure of apparent viscosity, and is directly related to the crosslinking density of the gel structure. The final designed system is sensitive to 1% changes in alginate concentration and .1% changes in calcium ion concentration.
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Details
- Title
- Depolarized light scattering and rheology of hydrogels
- Creators
- James Thomas Kolb - DU
- Contributors
- Elisabeth S. Papazoglou (Advisor) - Drexel University (1970-)Leonid Zubkov (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- School of Biomedical Engineering, Science, and Health Systems (1997-2026); Drexel University
- Other Identifier
- 2925; 991014632196904721