Thesis-1999-Myram.pdf (7.99 MB)
Modification of coal-tar pitch for use as a precursor for matrix carbon in carbon-carbon composites
thesis
posted on 2019-05-24, 14:33 authored by Sarah F. MyramIn this work a series of pitches was prepared from two binder pitches, A and B, by
sparging with hydrogen- and oxygen-containing gases, for different time intervals.
The pitches were then characterised in terms of a number of chemical and physical
properties. A model was developed which was used in conjunction with the pitch
properties to determine whether sparging had involved chemical processes.
It was found that for pitch A, sparging with hydrogen- and oxygen-containing
gases involved chemical changes but that these changes were independent of gas type.
These chemical changes lead to an increase in toluene insoluble material. This
material was unable to withstand pyrolysis and thus did not increase the carbon yield
of the pitch. Since the reactions in pitch A were independent of gas type it was
concluded that they were probably thermally induced.
For pitch B it was found that chemical reactions occurred and this time they
were dependant on the gas type. The reactions that occurred for pitch B in hydrogen
were concluded to be the same as those that occurred in pitch A but the reactions
taking place in pitch B treated with oxygen were different. These reactions lead to an
enhanced amount of toluene insoluble material. This material was able to withstand
pyrolysis and hence increased the carbon yield. This reaction was predicted to be
either an oxidative molecular growth or a decrease in volatility of polyaromatics
brought about by the addition of oxygen functionality.
In the second stage of this work carbon composites were fabricated using the
series of pitches as matrix precursors. The properties of the composites were obtained
and examined to see if they correlated with the properties of the pitches used to make
the composites. It was found that the composite characteristics correlated closely with
their constituent pitch characteristics, especially in the fact that the characteristics of
the composites made from pitches B treated with oxygen were markedly different
from all the others. It was concluded that the characteristics that were notably
different for pitches B treated with oxygen were a direct result of the different
reactions that occurred in these pitches compared to the reactions that had occurred in
the other pitches.
History
School
- Aeronautical, Automotive, Chemical and Materials Engineering
Department
- Chemical Engineering
Publisher
© Sarah MyramPublisher statement
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/Publication date
1999Notes
A Master's Thesis. Submitted in partial fulfilment of the requirements for the award of the degree of Master of Philosophy at Loughborough University.Language
- en