Electroactive shaping and shape memory of sequential dual-cured off-stoichiometric epoxy/CNT composites
Sequential dual-cured epoxy composites, based on off-stoichiometric thiol–epoxy mixtures catalysed by 1-methylimidazole, have been developed by adding carbon nanotubes (CNT). The epoxy curing process initially consists in two thermally activated curing stages: a first thiol–epoxy reaction and later...
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doaj-a96057a32d024090b5ff4c5ddf80e6d42021-10-09T04:39:20ZengElsevierJournal of Materials Research and Technology2238-78542021-11-011529702981Electroactive shaping and shape memory of sequential dual-cured off-stoichiometric epoxy/CNT compositesS.G. Prolongo0C.G. Díaz-Maroto1A. Jiménez-Suárez2Materials Science and Engineering Area, University Rey Juan Carlos, C/Tulipán s/n, 28933, Móstoles, Madrid, Spain; Corresponding author.Chemical and Environmental Engineering Group, University Rey Juan Carlos, C/Tulipán s/n, 28933, Móstoles, Madrid, Spain; Thermochemical Processes Unit, IMDEA Energy, Avda. Ramón de La Sagra 3, 28935, Móstoles, Madrid, SpainMaterials Science and Engineering Area, University Rey Juan Carlos, C/Tulipán s/n, 28933, Móstoles, Madrid, SpainSequential dual-cured epoxy composites, based on off-stoichiometric thiol–epoxy mixtures catalysed by 1-methylimidazole, have been developed by adding carbon nanotubes (CNT). The epoxy curing process initially consists in two thermally activated curing stages: a first thiol–epoxy reaction and later homopolymerization at a higher temperature. This system presents easy shaping/conforming and shape memory properties through thermo-mechanical treatments. Addition of the electrical CNT network into the epoxy matrix allows electrical switching, which increases its performance and in-situ applicability.The obtained results confirmed that CNTs catalyse the homopolymerization epoxy reaction, hindering the sequential curing process, due to the π–π anchoring of imidazole catalyser over the CNTs surface, enhanced by donor–acceptor interaction.Non-doped off-stoichiometric resins present relatively high thermal strength, with a glass transition temperature in the range of 73–109 °C, and high stiffness, with a storage modulus close to 2–3 GPa. They can be easily conformed at low temperature, 60 °C, before their second curing stage, showing a high shaping efficiency (around 90%) and full fixing efficiency (>98%).Nanocomposites with 0.2% CNT present efficient Joule heating, triggering the shape memory at low voltage, <80 V, with fixing and recovery efficiencies of 60–85%. In addition to its high in-situ applicability, the electrical resistive heating is faster and more efficient than conventional heating in an oven.http://www.sciencedirect.com/science/article/pii/S2238785421010917Sequential dual curingEpoxy nanocompositeCarbon nanotubesShape memoryJoule heating |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
S.G. Prolongo C.G. Díaz-Maroto A. Jiménez-Suárez |
spellingShingle |
S.G. Prolongo C.G. Díaz-Maroto A. Jiménez-Suárez Electroactive shaping and shape memory of sequential dual-cured off-stoichiometric epoxy/CNT composites Journal of Materials Research and Technology Sequential dual curing Epoxy nanocomposite Carbon nanotubes Shape memory Joule heating |
author_facet |
S.G. Prolongo C.G. Díaz-Maroto A. Jiménez-Suárez |
author_sort |
S.G. Prolongo |
title |
Electroactive shaping and shape memory of sequential dual-cured off-stoichiometric epoxy/CNT composites |
title_short |
Electroactive shaping and shape memory of sequential dual-cured off-stoichiometric epoxy/CNT composites |
title_full |
Electroactive shaping and shape memory of sequential dual-cured off-stoichiometric epoxy/CNT composites |
title_fullStr |
Electroactive shaping and shape memory of sequential dual-cured off-stoichiometric epoxy/CNT composites |
title_full_unstemmed |
Electroactive shaping and shape memory of sequential dual-cured off-stoichiometric epoxy/CNT composites |
title_sort |
electroactive shaping and shape memory of sequential dual-cured off-stoichiometric epoxy/cnt composites |
publisher |
Elsevier |
series |
Journal of Materials Research and Technology |
issn |
2238-7854 |
publishDate |
2021-11-01 |
description |
Sequential dual-cured epoxy composites, based on off-stoichiometric thiol–epoxy mixtures catalysed by 1-methylimidazole, have been developed by adding carbon nanotubes (CNT). The epoxy curing process initially consists in two thermally activated curing stages: a first thiol–epoxy reaction and later homopolymerization at a higher temperature. This system presents easy shaping/conforming and shape memory properties through thermo-mechanical treatments. Addition of the electrical CNT network into the epoxy matrix allows electrical switching, which increases its performance and in-situ applicability.The obtained results confirmed that CNTs catalyse the homopolymerization epoxy reaction, hindering the sequential curing process, due to the π–π anchoring of imidazole catalyser over the CNTs surface, enhanced by donor–acceptor interaction.Non-doped off-stoichiometric resins present relatively high thermal strength, with a glass transition temperature in the range of 73–109 °C, and high stiffness, with a storage modulus close to 2–3 GPa. They can be easily conformed at low temperature, 60 °C, before their second curing stage, showing a high shaping efficiency (around 90%) and full fixing efficiency (>98%).Nanocomposites with 0.2% CNT present efficient Joule heating, triggering the shape memory at low voltage, <80 V, with fixing and recovery efficiencies of 60–85%. In addition to its high in-situ applicability, the electrical resistive heating is faster and more efficient than conventional heating in an oven. |
topic |
Sequential dual curing Epoxy nanocomposite Carbon nanotubes Shape memory Joule heating |
url |
http://www.sciencedirect.com/science/article/pii/S2238785421010917 |
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