الفهرس 
Optical and structural properties of fibresOnly 14 pages are availabe for public view
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Abstract
This thesis aims to utilise two-beam interferometric technique in the determination of the optical, geometrical and thermo-mechanical properties of stretched fibres. This interferometric technique is used to determine the refractive indices and birefringence of polymeric fibres. These optical properties are related to the geometrical and mechanical properties of fibres by attaching of the drawing devices with the optical interferometric system. A general introduction is given in chapter 1 with a review of the previous work dedicated to the investigation of polymeric fibres under different mechanical stretching techniques. Moreover, chapter 2 introduces the description of the set-up and the theoretical considerations of these techniques are given. The concepts of mechanical properties of fibres with their theoretical consideration are discussed in this chapter. In chapter 3 a multi-mode opto-thermo mechanical stretching system was modified to study the changes in the 3D of optical and structural properties of a stretched fibre along its axis. The structural deformation of isotactic Polypropylene, (iPP), fibres were studied at different draw ratios. The modified system coupled with Pluta polarizing interference microscope was used to determine the variation of the birefringence in three dimensions during stretching process. Using this modified system, the multi-necking was detected. Subfringe analysis technique was used to determine the phase distribution of the obtained microinterferograms. In chapter 4 the hot-stage multi-mode opto-thermal stretching device attached to Pluta polarising interference microscope is used to study the online variations of the optical parameters of isotactic Polypropylene fibre as a function of the surrounding temperature. Also the variations of the birefringence profiles of isotactic Polypropylene at different stretching conditions are studied. This device allows the online examination of the chains orientation in more details at different draw ratios and surrounding temperatures. The influence of temperature on the stretched samples and necking phenomenon was investigated using the hot-stage stretching device presented in this paper. The experimental results are supported with the microinterferograms, which are given for illustration. This thesis presents some contributions to the opto-thermo-mechanical investigation of polymeric fibres under different thermal and mechanical conditions. Multi-mode opto-thermo-mechaincal stretching system was presented. Different optical and stretching properties were determined. This helped us to understand different phenomena observed during the variations of the mechanical and thermal conditions, e.g. neck formation and propagation corresponding to these variations.