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Title: Dynamics of oily and solid soil removal from fibres
Author: Pham, Thanh Nhan
ISNI:       0000 0001 3486 9271
Awarding Body: Nottingham Trent University
Current Institution: Nottingham Trent University
Date of Award: 2002
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This thesis reports the development of a novel single fibre optical method based upon attenuated total internal reflection (ATIR) for the study of the kinetics of the detergency process. This method is assessed for its ability to monitor the extent to which the fibre is soiled by liquids or solids. In this thesis, the focus is upon textile type fibres of polyester and Tencel, with the main focus on polyester fibres of 800 and 80 pm in diameter. Initial assessment of the method is performed using coiled PMMA optical fibres. An experimental apparatus based on a lock-in amplifier has been designed, tested and characterised over a range of conditions. The immersion of fibres in a series of alkanes demonstrates the increasing light attenuation as the refractive index of the outer medium approaches that of the fibre. The ability of the system to monitor the wetted length of the fibre via light attenuation was established. The system was then used to monitor the deposition of decane drops from a decane-water emulsion. Subsequently, the wetting of small portions of fibres by drops of water and the deposition of polystyrene particles of sizes 1.9, 3.15, 5 and 10 pm from suspension drops of a range of concentrations was considered. The particle deposition was forced by the natural evaporation of the drops. These studies showed a linear relationship between the covered area and the light attenuation with significantly higher attenuation due to the final deposition of particles compared to the initial wetted area. This study was then extended to the deposition of clay particles via evaporation. The interpretation of the trends in the ATIR light transmission signal in the particle deposition experiments has been developed using videomicroscopy and the quartz crystal microbalance (QCM) method. It was found that the penetration depth of the evanescent wave in the ATIR method is larger than that of the QCM. Furthermore, the contact line pinning during evaporation which was observed by videomicroscopy has also been recorded by the ATIR transmission signals. Clay deposition from aqueous solutions in which the fibres are immersed has also been studied. The rate of the deposition of the particles can be manipulated by adding electrolytes to the solution. To support the experimental work a simple quantitative model of the light transmission based on meridional rays in multimode fibres has been developed. Good agreement between model and experiments are found for the immersion study of polyester and the deposition of polystyrene particles onto polyester.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available