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Polymerisation of vinyl monomers in continuous-flow reactors. An experimental study, which includes digital computer modelling, of the homopolymerisation of styrene and methylmethacrylate by anionic and free radical mechanisms respectively in continuous flow-stirred-tank reactors.Bourikas, N. January 1976 (has links)
An introduction is given to the background theory and
scientific literature of the major subject areas of interest in
this thesis, namely the chemistry of free radical and anionic
polymerisation, molecular weight control in each type of polymerisation,
polymerisation reactors, computer simulation of
polymerisation processes and polymer characterisation by gel
permeation chromatography.
A novel computer model has been devised, based on the
analysis of the polymerisation process in terms of the reaction
extent of each reactant and the use of generation functions
to describe the concentration of living and dead polymeric
species, for the free radical, solution polymerisation of methylmethacrylate
in a CSTR. Both heat and mass balance expressions
have been described. Conversion, Mn and Mw were monitored.
To test the model a reactor was designed and constructed.
A detailed description of the reactor and the experimental
conditions used for the validation of the model are given.
The results of these studies are presented and excellent agreement
is shown between model predictions and experiments up to 30%
conversion for Mn
w and % conversion.
A similar study is described for the anionic polymerisation
of styrene in tetrahydrofuran as solvent, in a CSTR. In this
work the computer model becomes 'stiff' when realistic rate
constants are introduced in the kinetic expressions.
Experimental difficulties were encountered in obtaining
reproducible results in the anionic work. A new approach of
using 'scavengers' as protecting agents for the living chains
is described. A scavenger was successfully employed in the
preparation of block copolymers using a tubular reactor.
Block copolymerisation, in addition to providing a means of
checking the number of the 'living' chains inside the reactor,
is of interest in its own right.
All the experimental findings are discussed in relation
to the currently accepted views found in the scientific
literature.
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Polymerisation of vinyl monomers in continuous-flow reactors : an experimental study, which includes digital computer modelling, of the homopolymerisation of styrene and methylmethacrylate by anionic and free radical mechanisms respectively in continuous flow-stirred-tank reactorsBourikas, N. January 1976 (has links)
An introduction is given to the background theory and scientific literature of the major subject areas of interest in this thesis, namely the chemistry of free radical and anionic polymerisation, molecular weight control in each type of polymerisation, polymerisation reactors, computer simulation of polymerisation processes and polymer characterisation by gel permeation chromatography. A novel computer model has been devised, based on the analysis of the polymerisation process in terms of the reaction extent of each reactant and the use of generation functions to describe the concentration of living and dead polymeric species, for the free radical, solution polymerisation of methylmethacrylate in a CSTR. Both heat and mass balance expressions have been described. Conversion, Mn and Mw were monitored. To test the model a reactor was designed and constructed. A detailed description of the reactor and the experimental conditions used for the validation of the model are given. The results of these studies are presented and excellent agreement is shown between model predictions and experiments up to 30% conversion for Mn w and % conversion. A similar study is described for the anionic polymerisation of styrene in tetrahydrofuran as solvent, in a CSTR. In this work the computer model becomes 'stiff' when realistic rate constants are introduced in the kinetic expressions. Experimental difficulties were encountered in obtaining reproducible results in the anionic work. A new approach of using 'scavengers' as protecting agents for the living chains is described. A scavenger was successfully employed in the preparation of block copolymers using a tubular reactor. Block copolymerisation, in addition to providing a means of checking the number of the 'living' chains inside the reactor, is of interest in its own right. All the experimental findings are discussed in relation to the currently accepted views found in the scientific literature.
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