Search results for "Dielectric thermal analysis"

showing 3 items of 3 documents

Influence of chitin nanocrystals on the dielectric behaviour and conductivity of chitosan-based bionanocomposites

2018

[EN] A series of bionanocomposite films based on chitosan, reinforced with chitin nanocrystals, were developed, and assessed in terms of dielectric behaviour and conductivity by using an experimental methodology that allows avoiding the conductivity contribution and the exclusion of contact and interfacial polarization effects. The dielectric relaxations at low and high frequency and temperatures were modeled by Havriliak-Negami functions. Below the glass transition temperature (Tg), the gamma and beta relaxations were observed, which were related to intramolecular and non-cooperative segmental movements. At higher temperatures, an intermolecular and cooperative macromolecular movement, rel…

BionanocompositesSolucions polimèriquesMaterials scienceMaterial testingIonic bonding02 engineering and technologyDielectricActivation energyConductivity010402 general chemistry01 natural sciencesChitosanchemistry.chemical_compoundElectrical resistivity and conductivity[CHIM.ANAL]Chemical Sciences/Analytical chemistryComposite materialsChitosanChitosanIntermolecular forceGeneral EngineeringINGENIERIA DE LOS PROCESOS DE FABRICACION[CHIM.MATE]Chemical Sciences/Material chemistryCiència dels materials021001 nanoscience & nanotechnology0104 chemical sciencesChitin nanocrystals[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry[CHIM.POLY]Chemical Sciences/PolymersChemical engineeringchemistryMAQUINAS Y MOTORES TERMICOSCeramics and CompositesChitin nanocrystal0210 nano-technologyGlass transitionDielectric thermal analysis (DETA)
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Dielectric spectroscopy of novel thiol-ene/epoxy thermosets obtained from allyl-modified hyperbranched poly (ethyleneimine) and diglycidylether of bi…

2019

[EN] 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 gamma and beta relaxations and an intermolecular cooperative alpha…

Bisphenol AThermosetMaterials sciencePolymers and PlasticsSegmental cooperativityGeneral Physics and AstronomyThermosetting polymer02 engineering and technologyDielectric010402 general chemistry01 natural sciencesPentaerythritolDielectric thermal analysischemistry.chemical_compoundHyperbranched polymersCIENCIA DE LOS MATERIALES E INGENIERIA METALURGICAPolymer chemistryMaterials ChemistryEpoxy resinDielectric analysisOrganic ChemistryTermoplàsticsINGENIERIA DE LOS PROCESOS DE FABRICACIONEpoxyCiència dels materials021001 nanoscience & nanotechnology0104 chemical sciencesDielectric spectroscopychemistryIntramolecular forcevisual_artMAQUINAS Y MOTORES TERMICOSvisual_art.visual_art_medium0210 nano-technology
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Dielectric Spectroscopy of Recycled Polylactide

2014

The effects of multiple mechanical recycling on amorphous polylactide (PLA) were simulated by means of five successive injection-grinding cycles. The influence of the induced thermo-mechanical degradation on the dielectric properties of PLA was analysed. The relaxation spectra were studied in terms of the complex dielectric permittivity (ε0 and ε00) and the dielectric loss tangent, tg(d) in the frequency range from 102 to 107 Hz over the temperature interval from 0 C to 140 C. It was possible to distinguish two relaxations zones, one at low temperatures and high frequencies (b relaxation) and another at higher temperatures and lower frequencies (a relaxation). The individual relaxations wer…

Materials sciencePolymers and PlasticsThermodynamicsDielectricConductivityThermo-mechanical degradationsymbols.namesakeSegmental dynamicsDynamic fragilityMaterials ChemistryPoly(lactide) (PLA)RecyclingComposite materialResistència de materialsArrhenius equationMolar massCondensed Matter PhysicsDielectric spectroscopyAmorphous solidMechanics of MaterialsMAQUINAS Y MOTORES TERMICOSsymbolsRelaxation (physics)Dielectric lossMATEMATICA APLICADADielectric thermal analysis (DETA)
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