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Title: Modelling Plastics Pyrolysis by Thermogravimetry and Measurements of Molecular Weight Distribution
Author: Crewe, Robert John
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2007
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Abstract:
This thesis concerns the investigation of polymer pyrolysis by a combined approach of ' . , mathematical modelling and experimentation. This 'is done as a contribution towards better understanding how' materials behave in fire' situations. Thermogravimetric analysis has been investigated with regard to the accurate determination of kinetic parameters from thermogravimetric traces. This investigation has focused on various numerical methods that can determine the kinetic parameters from the curves and on correcting the buoyancy effect of the gas flowing through the analyser~ These mathematical techniques have then been applied to the thermogravimetric analysis of real plastics. The plastics investigated are; polystyrene, polymethyl methacrylate, polyvinyl chloride and flame retarded high impact polystyrene. Variations in kinetic parameters with heating rate are investigated in order to determine the ooent to which thermogravimetric analysis can shed light on fundamental chemical processes' occurring during pyrolysis. It is found that thermogravimetric analysis by itself is not realistically capable of shedding much' light on the chemistry occurring dl:lring pyrolysis. An alternative approach. that is subsequently considered is' to investigate polymer decomposition through variations in molecular weight distribution. This has allowed the description of polymer decomposition to be undertaken in terms of scission processes. In the cases of polystyrene and polymethyl methacrylate, it has been found (in agreement with the general literature) that the variations of molecular weight distribution are reminiscent of end-chain scission processes with small contributions of random scission. That said, it is also clear that there are features in both materials' decomposition profiles that requires further modelling. In the case of multi-component mixtures such as the flame retardant HIPS this modelling approach is unable to cope with the experimental observation in its current form.
Supervisor: Not available Sponsor: Not available
Qualification Name: University of Leeds, 2007 Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.485181  DOI: Not available
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