Title page for ETD etd-11292009-204923


Document Type Master's Dissertation
Author Manabile, Segaule Isaac
Email s26542707@tuks.co.za
URN etd-11292009-204923
Document Title Study of the early stages of carbonisation of some pitch materials of different composition
Degree MSc
Department Chemistry
Supervisor
Advisor Name Title
Prof W W Focke Committee Co-Chair
Prof B Rand Supervisor
Keywords
  • heat treatment
  • chemical composition
  • mesophase
  • pitch
  • green coke
Date 2009-09-02
Availability unrestricted
Abstract
The formation and development of mesophase from different pitches under carbonisation conditions was investigated. Members of the pyrolysis series were prepared from four pitches. A temperature range between 380 and 500C was used to follow mesophase development for each pitch. As-received pitches and their green cokes were characterised by thermomechanical analysis (glass transition temperature and softening point temperature), elemental analysis, Fourier transform infrared spectroscopy, thermogravimetry or differential thermogravimetry, and optical microscopy (mesophase content). Additional data about the evolution of different volatile products and about possible chemical reactions occurring during thermal decomposition were obtained from thermogravimetric mass spectrometric analysis. The effect of heating rate on the behaviour and carbon yield was also studied.

The results showed that the two anthracene oil pitches do not develop mesophase, whereas the medium-temperature and high-temperature pitches do. However, their textures are completely different. The medium-temperature pitch shows an improvement in texture from the mosaic to the coarse domain at 500C, whereas the high-temperature pitch shows flow domains. It was further shown that the process of preparing mesophase, i.e. the heat-treatment process, increases the aromaticity and carbon yield. Thermogravimetric mass spectrometric analysis showed that the dominant reaction for all the pitches is the condensation reaction, which is accompanied by the evolution of H2 and CO. The heating rate affects the behaviour of the pyrolysing pitches in that a lower heating rate lowers the carbon yield. This study gave insight into the influence of the nature and composition of the precursor on the formation of mesophase.

2009, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Manabile, SI 2009, Study of the early stages of carbonisation of some pitch materials of different composition, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-11292009-204923/ >

E1495/ag

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