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Title: Novel methods in the analysis of polymers using vibrational spectroscopy
Author: Llewelyn, Elizabeth Sara
ISNI:       0000 0001 3611 5668
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 1997
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The work described in this thesis involved the study of novel methods of analysing polymers using a unique FT-infrared and Raman continuous scanning spectrometer which allowed time resolved measurements. Three main experiments were carried out. One set of experiments (described in chapters 3 and 4) investigated the behaviour of polyethylene terephthalate (PET) and polyethylene 2,6-naphthalate (PEN) films whilst undergoing a small cyclic deformation. This showed how such a technique could increase the spectral information obtained. It was seen that the PEN submolecular structure is generally more stable than that of PET, and that despite their similar structures, the response of the two polymers was quite different. It was also possible to monitor the behaviour of individual submolecular groups as they were stressed dynamically at a range of temperatures. In chapter 5, a novel experiment is described which allowed sensitive and easy detection of dichroic spectra. By rotating the sample, the spectral differences for the orthogonal orientations are made simultaneously. This method has been demonstrated to successfully monitor levels of orientation of polymers. It is able to detect a dichroic difference for a draw ratio as low as 1.023, and also precisely the onset of orientation. Chapter 6 describes how the Raman tube in the spectrometer was redesigned to incorporate an analyser to enable high quality 180° scattering depolarised Raman spectroscopy. This enabled anisotropic Raman spectra to be recorded using the rotating cell. An ultra high modulus polyethylene rod was successfully studied in this way, described in chapter 7. The anisotropic spectra obtained showed striking variations in relative band intensities, and arguably components of doublets.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Infrared; Raman