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Blends of bitumen and polypropylene : their physico-chemical properties

Blends of bitumen and polypropylene : their physico-chemical properties
Blends of bitumen and polypropylene : their physico-chemical properties

The project was designed to study 'atactic polypropylenes/ bitumens, and their blends, as used in commercial waterproof roofing membranes. Low temperature DSC was used to investigate the lowering of the glass transition (Tg) of the blends by 'atactic polypropylene' ('APP'), in order to 6nd the optimum, and therefore most cost-efkctive, proportion of this additive. This value, about 17 % 'APP,' beyond which further addition made neghgible difference, was about the same as the known inversion point between APP- in-bitumen and bitumen-in-APP behaviour, so this relationship probably apphes to all such blends. This relationship is of value to the industry, and any technique for Aiding the inversion point would sufBce, such as the two much simpler methods that were devised - by melting and by degradation of a series of blends - and another using addition of DSC plots. Information was also gathered on oAer behaviour of the materials that was relevant to their use, /.g. aU aspects of weathering. TMA of 'APPs' under static load showed the creep behaviour of 'APPs,' gave linear coefGcient of e^gansion, and revealed stress- induced crystallization. Dynamic load TMA results led to the proposal of critical load and critical san^le depth, beyond which this occurs. Novel treatment of other dynamic load data, and of DSC data, indicated two new methods that could be used to find Tg. High temperature DSC work, particularly with hnked methods, measured 'APP' ciystallinity, showed the effects of repeated annealing and quenching upon it, showed that atactic PP oxidized faster than isotactic PP, and analyzed oxidation in air and decomposition in nitrogen. Thin layer chromatogr^hy with Game ionization detection (TLC-FID) achieved good separation of the four main components of 6ve bitumens. Long-term thermal degradation, monitored by percentage mass change under controlled conditions in hght and dark, on the supphed materials and on 'APPs' prepared in three ways, showed that bitumen and 'APP' protected each other and showed how crystalhnity, light level and temperature affected degradation. A mechanism for oxidative degradation was proposed that accounted for all the features of the percentage mass change graphs, and an Excel spreadsheet was used to show how this model could give rise to those features. Other techniques used during the work were FT-Raman, FT-IR, UV, MS and a density gradient column.

University of Southampton
Hanney, Maureen June
c36d6b2b-dce3-4887-b448-891aebb414f9
Hanney, Maureen June
c36d6b2b-dce3-4887-b448-891aebb414f9

Hanney, Maureen June (2000) Blends of bitumen and polypropylene : their physico-chemical properties. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The project was designed to study 'atactic polypropylenes/ bitumens, and their blends, as used in commercial waterproof roofing membranes. Low temperature DSC was used to investigate the lowering of the glass transition (Tg) of the blends by 'atactic polypropylene' ('APP'), in order to 6nd the optimum, and therefore most cost-efkctive, proportion of this additive. This value, about 17 % 'APP,' beyond which further addition made neghgible difference, was about the same as the known inversion point between APP- in-bitumen and bitumen-in-APP behaviour, so this relationship probably apphes to all such blends. This relationship is of value to the industry, and any technique for Aiding the inversion point would sufBce, such as the two much simpler methods that were devised - by melting and by degradation of a series of blends - and another using addition of DSC plots. Information was also gathered on oAer behaviour of the materials that was relevant to their use, /.g. aU aspects of weathering. TMA of 'APPs' under static load showed the creep behaviour of 'APPs,' gave linear coefGcient of e^gansion, and revealed stress- induced crystallization. Dynamic load TMA results led to the proposal of critical load and critical san^le depth, beyond which this occurs. Novel treatment of other dynamic load data, and of DSC data, indicated two new methods that could be used to find Tg. High temperature DSC work, particularly with hnked methods, measured 'APP' ciystallinity, showed the effects of repeated annealing and quenching upon it, showed that atactic PP oxidized faster than isotactic PP, and analyzed oxidation in air and decomposition in nitrogen. Thin layer chromatogr^hy with Game ionization detection (TLC-FID) achieved good separation of the four main components of 6ve bitumens. Long-term thermal degradation, monitored by percentage mass change under controlled conditions in hght and dark, on the supphed materials and on 'APPs' prepared in three ways, showed that bitumen and 'APP' protected each other and showed how crystalhnity, light level and temperature affected degradation. A mechanism for oxidative degradation was proposed that accounted for all the features of the percentage mass change graphs, and an Excel spreadsheet was used to show how this model could give rise to those features. Other techniques used during the work were FT-Raman, FT-IR, UV, MS and a density gradient column.

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Published date: 2000

Identifiers

Local EPrints ID: 464310
URI: http://eprints.soton.ac.uk/id/eprint/464310
PURE UUID: 6c0ddb1b-5e82-40e4-988d-772b0014a3d9

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Date deposited: 04 Jul 2022 22:03
Last modified: 16 Mar 2024 19:24

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Contributors

Author: Maureen June Hanney

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