| Autor: |
Griffith, J. D. |
| Rok vydání: |
2008 |
| Předmět: |
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| Druh dokumentu: |
Electronic Thesis or Dissertation |
| Popis: |
The work in this thesis contributes to an understanding of the evolution of the drying kinetics and internal microstructure of a model detergent paste (called a crutcher mix) during the spray drying stage in the manufacture of washing powders in order that the physical and cleaning properties of the final dried detergent powder can ultimately be more easily controlled and manipulated. Regularisation algorithms were developed and employed in conjunction with nuclear magnetic resonance (NMR) spectroscopy and relaxometry techniques to characterise both the bulk and individual constituent components of crutcher mix. In addition, novel 2-D relaxation methods were applied and used to characterise the sizes of the different phase domains within crutcher mix. The in-situ drying of crutcher mix has been investigated using NMR. Large samples have been studied to identify the changes in bulk properties, whilst studies on individual 10 µl droplets mimic the material geometry in an industrial spray dryer. Quantitative imaging and relaxometry experiments have been used to show that the drying is in the failing rate regime throughout and to deduce that there is preferential drying of the water-rich phase over the surfactant-rich phase. Novel rapid pulsed field gradient (PFG) experiments have been destroyed and then used to probe the dynamic evolution of the internal microstructure during drying. A parameter free model describing the drying of single detergent pate droplets has been established and compared favourably to experimental data. The model has been expanded to provide very preliminary simulations of the drying conditions within industrial spray dryers. A feasibility study looking into the use of NMR to study the absorption properties of the dried granular detergent product was also conducted. The ingress of water into a compacted detergent tablet has been monitored through the acquisition of 1-D image profiles of the water content and shown to exhibit Case II diffusion characteristics. |
| Databáze: |
Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
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