Network structure dependence on unconstrained isothermal-recovery processes for shape-memory thiol-epoxy "click" systems
Visualitza/Obre
Cita com:
hdl:2117/113435
Tipus de documentArticle
Data publicació2017-05-01
Condicions d'accésAccés obert
Llevat que s'hi indiqui el contrari, els
continguts d'aquesta obra estan subjectes a la llicència de Creative Commons
:
Reconeixement-NoComercial-SenseObraDerivada 3.0 Espanya
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 ( TprogTprog ) and isothermal-recovery temperatures ( TisoTiso ) 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 TisoTiso : 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 TgTg . The shape-recovery process is slower in materials with more densely crosslinked and hindered network structures. The shape-recovery time ( tsrtsr ) is significantly reduced when the isothermal-recovery temperature TisoTiso increases from below to above TgTg because the network relaxation dynamics accelerates. However, the temperature range from the beginning to the end of the recovery process is hardly affected by TisoTiso ; at higher TisoTiso 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<TgTiso<Tg to maximize the effect of the structure and/or by increasing TisoTiso to minimize the effect but increasing the shape-recovery rate.
CitacióBelmonte, A., Fernandez-Francos, X., de la Flor, S., Serra, À. Network structure dependence on unconstrained isothermal-recovery processes for shape-memory thiol-epoxy "click" systems. "Mechanics of time-dependent materials", 1 Maig 2017, vol. 21, núm. 2, p. 133-149.
ISSN1385-2000
Versió de l'editorhttps://link.springer.com/article/10.1007%2Fs11043-016-9322-z
Fitxers | Descripció | Mida | Format | Visualitza |
---|---|---|---|---|
MTDM9322_delta.pdf | 5,313Mb | Visualitza/Obre |