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Dielectric spectroscopy of novel thiol-ene/epoxy thermosets obtained from allyl-modified hyperbranched poly (ethyleneimine) and diglycidylether of bisphenol A

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Dielectric spectroscopy of novel thiol-ene/epoxy thermosets obtained from allyl-modified hyperbranched poly (ethyleneimine) and diglycidylether of bisphenol A

dc.contributor.author	Badia Valiente, José David
dc.contributor.author	Teruel-Juanes, Roberto
dc.contributor.author	Acebo, C.
dc.contributor.author	Gil Castell, O.
dc.contributor.author	Serra, A.
dc.contributor.author	Ribes Greus, A.
dc.date.accessioned	2019-11-12T11:01:03Z
dc.date.available	2021-01-10T05:45:05Z
dc.date.issued	2019
dc.identifier.uri	https://hdl.handle.net/10550/72174
dc.description.abstract	Dielectric Thermal Analysis (DETA) of a series of new thermoset obtained by click chemistry was performed. The new thermosets were obtained by a dual-curing process consisting in a first photochemical thiol-ene, followed by a thermal thiol-epoxy starting from an allyl-terminated hyperbranched poly(ethyleneimine) (HBPEI) and different proportions of diglycidylether of bisphenol A (DGEBA) and the corresponding stoichiometric proportions of pentaerythritol tetrakis (3-mercaptopropionate, PETMP). The dielectric behaviour was obtained experimentally supressing the conductive effects. Two sub-Tg intramolecular non-cooperative γ and β relaxations and an intermolecular cooperative α-relaxation were detected. The γ-relaxation was ascribed to the dipole orientation of the terminal thiol groups. Two γ relaxations γepo and γene were observed, according to the influence of the surroundings. Only thermosets with a content of flexible HBPEI/PETMP domains higher than a 50% w/w showed the γene relaxation at lower temperatures and higher frequencies. The β-relaxation was a non-Johari-Goldstein relaxation, ascribed to the dipole transfer of the linear CH2O(CO)CH2CH2 groups of the thiol constrained in the glassy state. The α-relaxation was ascribed to the long-term segmental movements of the thermosets, occurring during the transition from the glassy to the rubbery stage. A synergic effect of reducing the rigidity and compactness of the thermosets by the reduction of aromatic moieties of the DGEBA/PETMP units, and the increase of the flexibility induced by the addition of HBPEI/PETMP units affected the macromolecular movement of the thermosets.
dc.language.iso	eng
dc.relation.ispartof	European Polymer Journal, 2019, vol. 113, p. 98-106
dc.rights.uri	info:eu-repo/semantics/openAccess
dc.source	Badia Valiente, José David Teruel-Juanes, Roberto Acebo, C. Gil Castell, O. Serra, A. Ribes Greus, A. 2019 Dielectric spectroscopy of novel thiol-ene/epoxy thermosets obtained from allyl-modified hyperbranched poly (ethyleneimine) and diglycidylether of bisphenol A European Polymer Journal 113 98 106
dc.subject	Ciència dels materials
dc.subject	Termoplàstics
dc.title	Dielectric spectroscopy of novel thiol-ene/epoxy thermosets obtained from allyl-modified hyperbranched poly (ethyleneimine) and diglycidylether of bisphenol A
dc.type	info:eu-repo/semantics/article
dc.date.updated	2019-11-12T11:01:03Z
dc.identifier.doi	https://doi.org/10.1016/j.eurpolymj.2019.01.001
dc.identifier.idgrec	134923
dc.embargo.terms	24 months