Author, as appears in the article.: Belmonte A., Fernández-Francos X., De la Flor S., Serra À.

Department: Enginyeria Mecànica Química Analítica i Química Orgànica

URV's Author/s: De la Flor Lopez, Silvia / Fernández Francos, Xavier / Serra Albet, Maria Angels

Keywords: Thiol-epoxy Thermosets Temperature Stress Shape-memory polymer Progress Polymer networks Kinetics Isothermal-recovery Click chemistry Behavior

Abstract: The shape-memory response (SMR) of 'click' thiol-epoxy polymers produced using latent catalysts, with different network structure and thermo-mechanical properties, was tested on unconstrained shape-recovery processes under isothermal conditions. Experiments at several programming temperatures (Tprog) and isothermal-recovery temperatures (Tiso) were carried out, and the shape-memory stability was analyzed through various consecutive shape-memory cycles. The temperature profile during the isothermal-recovery experiments was monitored, and it showed that the shape-recovery process takes place while the sample is becoming thermally stable and before stable isothermal temperature conditions are eventually reached. The shape-recovery process takes place in two different stages regardless of Tiso: a slow initial stage until the process is triggered at a temperature strongly related with the beginning of network relaxation, followed by the typical exponential decay of the relaxation processes until completion at a temperature below or very close to Tg. The shape-recovery process is slower in materials with more densely crosslinked and hindered network structures. The shape-recovery time (tsr) is significantly reduced when the isothermal-recovery temperature Tiso increases from below to above Tg because the network relaxation dynamics accelerates. However, the temperature range from the beginning to the end of the recovery process is hardly affected by Tiso; at higher Tiso it is only slightly shifted to higher temperatures. These results suggest that the shape-recovery process can be controlled by changing the network structure and working at Tiso < Tg to maximize the effect of the structure and/or by increasing Tiso to minimize the effect but increasing the shaperecovery rate.

Thematic Areas: Mechanics Mechanical engineering Materials science, characterization & testing Materials science (miscellaneous) Materials science (all) Materiais General materials science General chemical engineering Engenharias iii Chemical engineering (miscellaneous) Chemical engineering (all) Aerospace engineering

ISSN: 13852000

Author's mail: xavier.fernandez@urv.cat silvia.delaflor@urv.cat angels.serra@urv.cat

Author identifier: 0000-0002-3492-2922 0000-0002-6851-1371 0000-0003-1387-0358

Last page: 149

Record's date: 2023-02-18

Journal volume: 21

Papper version: info:eu-repo/semantics/acceptedVersion

Link to the original source: https://link.springer.com/article/10.1007/s11043-016-9322-z

Licence document URL: http://repositori.urv.cat/ca/proteccio-de-dades/

Papper original source: Mechanics Of Time-Dependent Materials. 21 (2): 133-149

APA: Belmonte A., Fernández-Francos X., De la Flor S., Serra À. (2017). Network structure dependence on unconstrained isothermal-recovery processes for shape-memory thiol-epoxy 'click' systems. Mechanics Of Time-Dependent Materials, 21(2), 133-149. DOI: 10.1007/s11043-016-9322-z

Article's DOI: 10.1007/s11043-016-9322-z

Entity: Universitat Rovira i Virgili

Journal publication year: 2017

First page: 133

Publication Type: Journal Publications