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Inhibition of polyimide photodegradation by incorporation of titanate nanotubes into a composite

Inhibition of polyimide photodegradation by incorporation of titanate nanotubes into a composite
Inhibition of polyimide photodegradation by incorporation of titanate nanotubes into a composite

The effect of UV light exposure on the properties of hexafluoroisopropylidene-diphthalic anhydride–oxydianiline (6FDA–ODA) polyimide (PI) and polyimide–titanate nanotube (TiNT/PI) composites has been studied using Raman spectroscopy, optical microscopy, nanoidentation and TEM. The degree of polymer photodegradation was estimated by measuring the change in affinity to a positively charged dye (methylene blue, MB). The mechanism of photoassisted transformations in polyimides usually involves scission of polymer chains accompanied by appearance of active radicals, which undergo further rapid transformations to more stable phenol, amine, and carboxylic functional groups. The accumulation of these groups can increase the degree of adsorption of charged dyes in the photodegraded polymer. It was found that neat PI showed a significantly increased capacity to adsorb MB after irradiation with UV, reaching a plateau after 1 h. In contrast, TiNT/PI composite demonstrated a much slower rise in concentration of adsorbed MB even after 4 h of UV exposure. Raman spectra indicated cleavage of C=O and C–F bonds in PI while only the C–F bond was damaged in TiNT/PI. Shorter cracks (≈ 40 µm long) appeared in TiNT/PI composites whereas macro cracks (> 100 µm) were visible in neat PI after 3 h of UV exposure. Brittleness was studied by comparing plasticity index which varied from 0 to 1 (0 corresponding to the most brittle material and 1 the most ductile one). Plasticity index reduced by 51% and 2% for PI and TiNT/PI, respectively after 3 h UV irradiation, indicating that TiNT can protect underlying PI from further damage. The hardness of neat PI decreased whereas, for TiNT/PI, it increased under UV, suggesting crosslinking of broken polymer chains with nanotubes. Graphical Abstract: Photodegradation of a titanate nanotubes/polyimide composite can lead to cross-linking of broken polymer chains by nanostructured material, resulting in increased hardness.[Figure not available: see fulltext.].

Ceramics, Dye staining, Early detection, Mechanism of photodegradation, Nanocomposites
1566-2543
1-11
Harito, Christian
d146fa4e-fa33-40fc-b4b2-f4a77e0e75e6
Bavykin, Dmitry V.
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Yuliarto, Brian
3817e4d8-9d7a-49a5-8a47-2a7dd7a0a9f3
Dipojono, Hermawan K.
5027e0d4-440c-4347-b015-8c40505fb22a
Walsh, Frank C.
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Harito, Christian
d146fa4e-fa33-40fc-b4b2-f4a77e0e75e6
Bavykin, Dmitry V.
1e9fabfc-d078-4585-876f-85ff33b7eed5
Yuliarto, Brian
3817e4d8-9d7a-49a5-8a47-2a7dd7a0a9f3
Dipojono, Hermawan K.
5027e0d4-440c-4347-b015-8c40505fb22a
Walsh, Frank C.
309528e7-062e-439b-af40-9309bc91efb2

Harito, Christian, Bavykin, Dmitry V., Yuliarto, Brian, Dipojono, Hermawan K. and Walsh, Frank C. (2019) Inhibition of polyimide photodegradation by incorporation of titanate nanotubes into a composite. Journal of Polymers and the Environment, 1-11. (doi:10.1007/s10924-019-01443-w).

Record type: Article

Abstract

The effect of UV light exposure on the properties of hexafluoroisopropylidene-diphthalic anhydride–oxydianiline (6FDA–ODA) polyimide (PI) and polyimide–titanate nanotube (TiNT/PI) composites has been studied using Raman spectroscopy, optical microscopy, nanoidentation and TEM. The degree of polymer photodegradation was estimated by measuring the change in affinity to a positively charged dye (methylene blue, MB). The mechanism of photoassisted transformations in polyimides usually involves scission of polymer chains accompanied by appearance of active radicals, which undergo further rapid transformations to more stable phenol, amine, and carboxylic functional groups. The accumulation of these groups can increase the degree of adsorption of charged dyes in the photodegraded polymer. It was found that neat PI showed a significantly increased capacity to adsorb MB after irradiation with UV, reaching a plateau after 1 h. In contrast, TiNT/PI composite demonstrated a much slower rise in concentration of adsorbed MB even after 4 h of UV exposure. Raman spectra indicated cleavage of C=O and C–F bonds in PI while only the C–F bond was damaged in TiNT/PI. Shorter cracks (≈ 40 µm long) appeared in TiNT/PI composites whereas macro cracks (> 100 µm) were visible in neat PI after 3 h of UV exposure. Brittleness was studied by comparing plasticity index which varied from 0 to 1 (0 corresponding to the most brittle material and 1 the most ductile one). Plasticity index reduced by 51% and 2% for PI and TiNT/PI, respectively after 3 h UV irradiation, indicating that TiNT can protect underlying PI from further damage. The hardness of neat PI decreased whereas, for TiNT/PI, it increased under UV, suggesting crosslinking of broken polymer chains with nanotubes. Graphical Abstract: Photodegradation of a titanate nanotubes/polyimide composite can lead to cross-linking of broken polymer chains by nanostructured material, resulting in increased hardness.[Figure not available: see fulltext.].

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Harito 2019 Article Inhibition Of Polyimide Photodegradation - Version of Record
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More information

Accepted/In Press date: 1 January 2019
e-pub ahead of print date: 17 April 2019
Keywords: Ceramics, Dye staining, Early detection, Mechanism of photodegradation, Nanocomposites

Identifiers

Local EPrints ID: 430741
URI: http://eprints.soton.ac.uk/id/eprint/430741
ISSN: 1566-2543
PURE UUID: e7aae2c4-13fa-4ed4-9a78-e4ebeeca118f

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Date deposited: 10 May 2019 16:30
Last modified: 25 Nov 2021 18:52

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Contributors

Author: Christian Harito
Author: Brian Yuliarto
Author: Hermawan K. Dipojono
Author: Frank C. Walsh

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