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Next generation polyurethanes for enhanced durability pre-finished architectural steel products. / Jenet Wray

Swansea University Author: Jenet Wray

Abstract

This research has focussed on the photo-oxidation of polyurethane coatings with aim to identify formulations with enhanced durability. The stability of a coating against the effects of environmental ultraviolet (UV) light poses a challenge to coating manufacturers particularly since almost all coati...

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Published: 2008
Institution: Swansea University
Degree level: Doctoral
Degree name: EngD
URI: https://cronfa.swan.ac.uk/Record/cronfa42649
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first_indexed 2018-08-02T18:55:13Z
last_indexed 2018-08-03T10:10:42Z
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spelling 2018-08-02T16:24:29.9774026 v2 42649 2018-08-02 Next generation polyurethanes for enhanced durability pre-finished architectural steel products. 680a6f78e1a99b990ea8c65944b0bba3 NULL Jenet Wray Jenet Wray true true 2018-08-02 This research has focussed on the photo-oxidation of polyurethane coatings with aim to identify formulations with enhanced durability. The stability of a coating against the effects of environmental ultraviolet (UV) light poses a challenge to coating manufacturers particularly since almost all coatings contain titanium dioxide (TiO2) as a pigment. It is widely acknowledged that TiO2 can become photoactivated by incident UV light, causing initiation of free radicals which under go reactions with the polymeric matrix and result in degradation of the coating. Previous research has identified a novel accelerated weathering test that allows quantification of coating photo-oxidation by measurement of evolved carbon dioxide (CO2) gas using a Fourier Transform Infrared (FTIR) spectrometer. The FTIR flat panel irradiation apparatus was used in conjunction with QUV A and xenon arc weathering in order to assess the durability of polyurethane coatings. Out of a range of TiO2 pigments Tronox R-KB-4 was the most stable for production of polyurethane coatings. It was found that alterations to the coating formulation, namely replacement of the standard durability polyester with one expected to improve UV durability did not provide the improvements anticipated. The polyurethane formulation containing a polyisocyanate cross-linker based on a combination of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) showed the best durability and most promise for improvement of commercial coatings. The effects of additives commonly used in commercial polyurethane coatings were investigated. It was found that although the addition of coloured pigments and texturing agents commonly affected coating durability, the majority of increase in coating degradation was due to the unstable nature of organic matting and texturing agents. Finally it was shown that the dispersion of a TiO2 pigment within polymeric matrix can significantly affect is durability. Coatings containing poorly dispersed TiO2 pigments showed a significant reduction in durability compared to those containing an optimum dispersion of TiO2. E-Thesis Materials science. 31 12 2008 2008-12-31 COLLEGE NANME Engineering COLLEGE CODE Swansea University Doctoral EngD 2018-08-02T16:24:29.9774026 2018-08-02T16:24:29.9774026 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised Jenet Wray NULL 1 0042649-02082018162511.pdf 10805425.pdf 2018-08-02T16:25:11.0830000 Output 24956044 application/pdf E-Thesis true 2018-08-02T16:25:11.0830000 false
title Next generation polyurethanes for enhanced durability pre-finished architectural steel products.
spellingShingle Next generation polyurethanes for enhanced durability pre-finished architectural steel products.
Jenet Wray
title_short Next generation polyurethanes for enhanced durability pre-finished architectural steel products.
title_full Next generation polyurethanes for enhanced durability pre-finished architectural steel products.
title_fullStr Next generation polyurethanes for enhanced durability pre-finished architectural steel products.
title_full_unstemmed Next generation polyurethanes for enhanced durability pre-finished architectural steel products.
title_sort Next generation polyurethanes for enhanced durability pre-finished architectural steel products.
author_id_str_mv 680a6f78e1a99b990ea8c65944b0bba3
author_id_fullname_str_mv 680a6f78e1a99b990ea8c65944b0bba3_***_Jenet Wray
author Jenet Wray
author2 Jenet Wray
format E-Thesis
publishDate 2008
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 1
active_str 0
description This research has focussed on the photo-oxidation of polyurethane coatings with aim to identify formulations with enhanced durability. The stability of a coating against the effects of environmental ultraviolet (UV) light poses a challenge to coating manufacturers particularly since almost all coatings contain titanium dioxide (TiO2) as a pigment. It is widely acknowledged that TiO2 can become photoactivated by incident UV light, causing initiation of free radicals which under go reactions with the polymeric matrix and result in degradation of the coating. Previous research has identified a novel accelerated weathering test that allows quantification of coating photo-oxidation by measurement of evolved carbon dioxide (CO2) gas using a Fourier Transform Infrared (FTIR) spectrometer. The FTIR flat panel irradiation apparatus was used in conjunction with QUV A and xenon arc weathering in order to assess the durability of polyurethane coatings. Out of a range of TiO2 pigments Tronox R-KB-4 was the most stable for production of polyurethane coatings. It was found that alterations to the coating formulation, namely replacement of the standard durability polyester with one expected to improve UV durability did not provide the improvements anticipated. The polyurethane formulation containing a polyisocyanate cross-linker based on a combination of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) showed the best durability and most promise for improvement of commercial coatings. The effects of additives commonly used in commercial polyurethane coatings were investigated. It was found that although the addition of coloured pigments and texturing agents commonly affected coating durability, the majority of increase in coating degradation was due to the unstable nature of organic matting and texturing agents. Finally it was shown that the dispersion of a TiO2 pigment within polymeric matrix can significantly affect is durability. Coatings containing poorly dispersed TiO2 pigments showed a significant reduction in durability compared to those containing an optimum dispersion of TiO2.
published_date 2008-12-31T03:53:23Z
_version_ 1763752650251173888
score 11.013082

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