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Title: An investigation of the adhesion and ageing of polysulfide sealant systems
Author: Birembaut, Fabrice
ISNI:       0000 0001 3465 1184
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 2002
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The recent changes in the European laws about pollutants are forcing the Aerospace industry to find new formulas for the sealants used in aircraft fuel tanks. The current formulas contain chromium, which is a very dangerous pollutant for the environment. The first aim of this thesis is to design an accelerated ageing test to help in screening the new formulae that will be used in the future. The use of an ultrasonic heating bath reveals itself to be of great advantage compared to other devices in which the sealant is enclosed for the time of the experiment. The several techniques, including hardness testing, mini-peel testing, mass spectrometry coupled with gas chromatography and UV/Visible spectroscopy are assessed and give invaluable clues to validate a new formula. In another chapter, the microscopic point of view is investigated. The Surface Enhanced Raman Scattering (SERS) technique is thus used to investigate the behaviour of the polysulfide molecules used in the Aerospace industry when they absorb onto the metal surface. First, various smaller molecules, a disulfide and a collection of thiols and dithiols, will be studied to create a model. Using this model it will be possible to interpret the spectrum of the liquid polymer molecule. Moreover, some calculations will be used to decide between two remaining possibilities, on the most credible behaviour of the molecule. There will finally be two aims in the last chapter. The first one will be to look at the coupling agents used to promote the adhesion of the polysulfide sealants in the aeroplanes, using the same SERS technique. Because of the commercial sensitivity of the product and because of its complexity, a model will be created to help understanding what happens at the surface neighbourhood. The second aim will be to combine the two model systems to study the interactions between the polysulfide and the adhesion promoter, at the microscopic level, when they are both adsorbed on the same metal surface.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available