Temperature modulated differential scanning calorimetry – extension to high and low frequencies

Shoifet, Evgeni; Schulz, Gunnar; Schick, Christoph

doi:10.1016/j.tca.2014.10.010

Cited by 60 publications

(42 citation statements)

References 48 publications

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“…Simultaneous multi-frequency measurements can thus be performed [17,18]. Temperature-modulated measurements can also be performed by using fast scanning nano-calorimeters [19,20], which allow the accessible frequency range to be extended to higher frequencies (0.1–100 Hz) [21]. In this review, however, only experiments carried out with conventional TMDSC instruments (sinusoidal or sawtooth temperature-modulation) will be reported and discussed.…”

Section: Introductionmentioning

confidence: 99%

Crystallization of Polymers Investigated by Temperature-Modulated DSC

Righetti

2017

Materials

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The aim of this review is to summarize studies conducted by temperature-modulated differential scanning calorimetry (TMDSC) on polymer crystallization. This technique can provide several advantages for the analysis of polymers with respect to conventional differential scanning calorimetry. Crystallizations conducted by TMDSC in different experimental conditions are analysed and discussed, in order to illustrate the type of information that can be deduced. Isothermal and non-isothermal crystallizations upon heating and cooling are examined separately, together with the relevant mathematical treatments that allow the evolution of the crystalline, mobile amorphous and rigid amorphous fractions to be determined. The phenomena of ‘reversing’ and ‘reversible‘ melting are explicated through the analysis of the thermal response of various semi-crystalline polymers to temperature modulation.

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Section: Introductionmentioning

confidence: 99%

Crystallization of Polymers Investigated by Temperature-Modulated DSC

Righetti

2017

Materials

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“…The glass transition is characterized by assessing the limiting T f -that is, the one attained after cooling at a given rate. Furthermore, step response analysis [38], providing the complex specific heat, was employed to characterize the molecular mobility. Our results show tremendous T f negative deviations from bulk behavior.…”

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confidence: 99%

“…Step response analysis [38] consisted of applying a temperature jump of 2 K followed by isotherms of duration 0.1 and 0.5 s. In such a way the instantaneous heat flow rate HFðtÞ and the cooling rate β c ðtÞ are obtained. These can be Fourier-transformed to determine the complex specific heat:…”

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confidence: 99%

Thermodynamic Ultrastability of a Polymer Glass Confined at the Micrometer Length Scale

Monnier

Cangialosi

2018

Phys. Rev. Lett.

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We employ fast scanning calorimetry to assess the thermodynamic state attained after a given cooling rate and the molecular mobility of glassy poly(4-tert-butylstyrene) confined at the micrometer length scale. We show that, for such a large confinement length scale, thermodynamic states with a fictive temperature (T f) 80 K below the polymer glass transition temperature (T g) are attained, which allows to bypass the geological timescales required for bulk glasses. Access to such states is promoted by a fast mechanism of equilibration. Importantly, the tremendous T f decrease takes place while the molecular mobility remains bulklike, indicating marked decoupling between vitrification kinetics and molecular mobility.

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“…One of these findings was that no decoupling is seen in 5PPE when comparing the temperature dependence of 6 different timescales 54 . This result was later supported by result from the group of C. Schick who compared dielec-tric and specific heat spectroscopy with lower accuracy but over larger range in dynamics 58 .…”

Section: And References Therein)mentioning

confidence: 70%

Communication: High pressure specific heat spectroscopy reveals simple relaxation behavior of glass forming molecular liquid

Roed

Niss

Jakobsen

2015

The Journal of Chemical Physics

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The frequency dependent specific heat has been measured under pressure for the molecular glass forming liquid 5-polyphenyl-4-ether in the viscous regime close to the glass transition. The temperature and pressure dependences of the characteristic time scale associated with the specific heat is compared to the equivalent time scale from dielectric spectroscopy performed under identical conditions. It is shown that the ratio between the two time scales is independent of both temperature and pressure. This observation is non-trivial and demonstrates the existence of specially simple molecular liquids in which different physical relaxation processes are both as function of temperature and pressure/density governed by the same underlying "inner clock." Furthermore, the results are discussed in terms of the recent conjecture that van der Waals liquids, like the measured liquid, comply to the isomorph theory.

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Temperature modulated differential scanning calorimetry – extension to high and low frequencies

Cited by 60 publications

References 48 publications

Crystallization of Polymers Investigated by Temperature-Modulated DSC

Crystallization of Polymers Investigated by Temperature-Modulated DSC

Thermodynamic Ultrastability of a Polymer Glass Confined at the Micrometer Length Scale

Communication: High pressure specific heat spectroscopy reveals simple relaxation behavior of glass forming molecular liquid

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