Glass transition investigated by a combined protocol using thermostimulated depolarization currents and differential scanning calorimetry

Delbreilh, Laurent; Negahban, Mehrdad; Benzohra, M.; Lacabanne, C.; Saiter, Jean‐Marc

doi:10.1007/s10973-009-0060-1

Cited by 25 publications

(13 citation statements)

References 28 publications

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“…This limited experimental window led to Arrhenius-like dependencies of a broad family of strong and even fragile polymers [45][46][47][48]. The determination of calorimetric fragility index in these constraining conditions was then tainted by significant uncertainties.…”

Section: Resultsmentioning

confidence: 99%

Combining Flash DSC, DSC and broadband dielectric spectroscopy to determine fragility

Dhôtel

Rijal

Delbreilh

et al. 2015

J Therm Anal Calorim

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New experimental results focused on Flash DSC, DSC and broadband dielectric spectroscopy investigations are reported in this work. The fictive temperatures and fragility indexes are estimated from Flash DSC experiments and compared to values obtained from classical DSC. The consistency of the Tool-NarayanaswamyMoynihan model and fragility concept is then investigated over a large range of cooling rates. Indeed, the Flash DSC allows exploring thermal properties of materials over a continuous and broad range of heating and cooling rates, complementary to rates usually available with DSC. The reliability of investigations is also demonstrated by comparing results obtained from two model amorphous polymeric systems: polystyrene and poly(ethylene terephthalate)-glycol. The temperature dependence of the cooling rate obtained by Flash DSC and DSC is also compared to the temperature dependence of the relaxation times obtained from broadband dielectric spectroscopy, experiment considered as the reference concerning the fragility measurements. The comparison of these two dependencies implies a better understanding about the origin of the temperature dependence of the cooling rate.

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Section: Resultsmentioning

confidence: 99%

Combining Flash DSC, DSC and broadband dielectric spectroscopy to determine fragility

Dhôtel

Rijal

Delbreilh

et al. 2015

J Therm Anal Calorim

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“…The equivalent frequency depend on the relaxation time s(T m ) recorded at the temperature T m at the maximum of elementary peak. Elementary TSC thermograms [29,30] were recorded with a poling window of 5 K. Then the field was removed and the sample cooled down to a temperature T p -40 K. The depolarization current was recorded with a constant heating rate q h . The series of elementary thermograms was recorded by shifting the poling window by 5 K towards higher temperature.…”

Section: Methodsmentioning

confidence: 99%

Dielectric relaxations in PEEK by combined dynamic dielectric spectroscopy and thermally stimulated current

Leonardi

Dantras

Dandurand

et al. 2012

J Therm Anal Calorim

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The molecular dynamics of a quenched poly (ether ether ketone) (PEEK) was studied over a broad frequency range from 10-3 to 10 6 Hz by combining dynamic dielectric spectroscopy (DDS) and thermo-stimulated current (TSC) analysis. The dielectric relaxation losses e 00 KK has been determined from the real part e 0 T(x) thanks to Kramers-Kronig transform. In this way, conduction and relaxation processes can be analyzed independently. Two secondary dipolar relaxations, the c and the b modes, corresponding to non-cooperative localized molecular mobility have been pointed out. The main a relaxation appeared close to the glass transition temperature as determined by DSC; it has been attributed to the delocalized cooperative mobility of the free amorphous phase. The relaxation times of dielectric relaxations determined with TSC at low frequency converge with relaxation times extracted from DDS at high frequency. This correlation emphasized continuity of mobility kinetics between vitreous and liquid state. The dielectric spectroscopy exhibits the a c relaxation, near 443 K, which has been associated with the rigid amorphous phase confined by crystallites. This present experiment demonstrates coherence of the dynamics of the PEEK heterogeneous amorphous phase between glassy and liquid state and significantly improve the knowledge of molecular/dynamic structure relationships.

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“…Thermally stimulated depolarization current [21] can be used to take into account this specificity. This technique is particularly suitable to investigate physical aging of polymer [22][23][24][25]. Bonded assemblies may be considered as a plane capacitor.…”

Section: Introductionmentioning

confidence: 99%

Enthalpy relaxation phenomena of epoxy adhesive in operational configuration: Thermal, mechanical and dielectric analyses

Caussé

Dantras

Tonon³

et al. 2014

Journal of Non-Crystalline Solids

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International audienceThermal cycling in space environment can cause physical aging of polymers used in structural adhesive bonded joint. Later, they can initiate failure. A methodology to follow physical aging effects on their thermal, mechanical and dielectric properties is applied to a commercial epoxy adhesive. The analytic description, using Tool, Narayanaswamy and Moynihan model gives a good description of the enthalpy relaxation. It is completed by a phenomenological analysis of the evolution of the adhesive thermal transitions, mechanical properties and mo- lecularmobility. Testedsamples with bondedassembly are representative ofin servicecon fi gurations. The in fl u- ence of physical aging on the adhesive and the associated bonded assemblies is analyzed

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Glass transition investigated by a combined protocol using thermostimulated depolarization currents and differential scanning calorimetry

Cited by 25 publications

References 28 publications

Combining Flash DSC, DSC and broadband dielectric spectroscopy to determine fragility

Combining Flash DSC, DSC and broadband dielectric spectroscopy to determine fragility

Dielectric relaxations in PEEK by combined dynamic dielectric spectroscopy and thermally stimulated current

Enthalpy relaxation phenomena of epoxy adhesive in operational configuration: Thermal, mechanical and dielectric analyses

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