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Title: Deformation micromechanics of process controlled cellulose fibres using Raman spectroscopy and X-ray diffraction
Author: Kong, Kenny
ISNI:       0000 0004 2711 6505
Awarding Body: The University of Manchester
Current Institution: University of Manchester
Date of Award: 2007
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Raman spectroscopy has been used to follow the defonnation micromechanics of a range of process---controlled fibres. The fibres were solvent spun using a N-methylmorpholine N-{)xide/ cellulose system. Single fibres are defonned in tension, and it is shown that the 1095 cm-l and 1414 cm-l Raman bands, corresponding to the C-O stretch mode and the side group (C-O--H) along the chain respectively, shift towards a lower wavenumber upon the application of external tensile defonnation. The shift profile of the 1095 cm-' band is shown to be non-linear, following the shape of the stress-strain curve, and the initial shift rate is shown to be directly related to the stiffness of the fibre. This band shift rate with respect to strain is shown to increase with increasing crystall ine orientation. The 1414 cm·1 band also shifts non-linearly and rapidly reaches a plateau with both strain and stress. This is thought to be due to the breakdown of hydrogen bonding in the structure, and a potential cause of the yield point in the mechanics of the fibres. The crystalline modulus and orientation of regenerated cellulose are measured using a wide-angle X-ray diffraction method. The crystalline modulus appears to vary with fibres having different orientations. It is shown that whilst the c-spacing of crystals increases with tensile stress, the crystalline fraction reorients to the direction of the fibre axis. An average shear modulus for these fibres is detennined by placing the data on a master curve and fitting with a model equation. Structure-property relationships are derived from the molecular and crystal defonnation characteristics of cellulose fibres using Raman spectroscopy and X-ray diffraction. This represents, for the first time, a full analysis of the relationship between structure and mechanics. at a local scale, of these regenerated cellulose fibres. Using a set of hypotheses tested on the experimental data, it is possible to distinguish unifonn stress and unifonn strain beha"iourNo portion of work referred to within this thesis has been submitted in support of an application for another degree or qualification of this or any other uni\crsity. or other institution of learning
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available