Influence of sulfur content and curing time on the glass transition parameters in SBR vulcanizates: an ultrasonic study

Youssef, Moheb H.

doi:10.1016/s0142-9418(02)00088-0

Cited by 14 publications

(8 citation statements)

References 25 publications

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“…The temperature dependence of the complex dielectric permittivity exhibits an anomalous behavior at low temperatures (close to 175 K). This behavior is attributed to the dynamic glass transition, usually referred as a primary α relaxation, due to a relatively large‐scale cooperative motion of many backbone segments in amorphous phase of PDMS .…”

Section: Resultsmentioning

confidence: 99%

Ultrasonic and dielectric relaxations in PDMS/ZnO nanocomposite

Belovickis

Macutkevič

Svirskas

et al. 2015

Physica Status Solidi (b)

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In this article, we present the impact of ZnO nanoparticles on ultrasonic and dielectric properties of Polydimethylsiloxane (PDMS)-based nanocomposites in a wide temperature range. The complex dielectric permittivity was measured as a function of the frequency at various temperatures and it was shown that the magnitude and the position of the dielectric loss peak in the temperature scale depend on the concentration of fillers in PDMS/ ZnO composite. The temperature dependences of ultrasonic wave attenuation showed attenuation peaks similar to those obtained by means of the dielectric spectroscopy. These peaks are attributed to the dynamic glass transition and obey the Vogel-FulcherTammann (VFT) equation. Values of the static glass transition temperature obtained analyzing the dielectric and ultrasonic data are consistent and increase with the concentration of ZnO. The ultrasonic wave attenuation and velocity in these composites depend on the filler concentration.

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Section: Resultsmentioning

confidence: 99%

Ultrasonic and dielectric relaxations in PDMS/ZnO nanocomposite

Belovickis

Macutkevič

Svirskas

et al. 2015

Physica Status Solidi (b)

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“…The main dielectric anomaly was observed at about 175 K. It is related to the glass transition (α relaxation) in pure PDMS. [23] The α relaxation is due to a large-scale collective motion of many backbone segments in the amorphous phase of PDMS. The additional dielectric anomaly was clearly observed as the maximum of dielectric losses in the temperature range 200-250 K (depending on the measurements frequency) and the change in the slope of temperature dependence of the dielectric permittivity.…”

Section: Resultsmentioning

confidence: 99%

Dielectric properties of polydimethylsiloxane composites filled with SrTiO₃ nanoparticles

et al. 2021

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This article deals with the dielectric properties of polydimethylsiloxane (PDMS) nanocomposites filled with SrTiO3 nanoparticles. The investigations were performed over a very broad range of frequencies (20 Hz to 3 THz). Almost no dielectric dispersion was observed in all the composites at room temperature over the entire range of measurement frequencies, and the dielectric losses were also very low under these conditions (<1.9). The dielectric dispersion was observed at lower temperatures (below 280 K), due to relaxation at the PDMS/SrTiO3 interface and in the bulk polymer. The relaxation time for both cases followed the Vogel–Vulcher law, while the freezing temperature was substantially lower for relaxation at the PDMS/SrTiO3 interface.

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“…The macroscopic properties of rubbers required for industrial applications are strongly related to the complex structure of the three-dimensional network of crosslinks formed during vulcanization [17][18][19][20][21][22]. This structure is defined by the number and spatial distribution of crosslinks and by their functionality and chemical nature, as well as by the presence of defects (pendant chains, loops, and chain modifications) and entanglements.…”

Section: Introductionmentioning

confidence: 99%

Influence of Sulfur-Curing Conditions on the Dynamics and Crosslinking of Rubber Networks: A Time-Domain NMR Study

et al. 2022

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The characterization of the structural and dynamic properties of rubber networks is of fundamental importance in rubber science and technology to design materials with optimized mechanical properties. In this work, natural and isoprene rubber networks obtained by curing at three different temperatures (140, 150, and 170 °C) and three different sulfur contents (1, 2, and 3 phr) in the presence of a 3 phr accelerator were studied using a combination of low-field time-domain NMR (TD-NMR) techniques, including 1H multiple-quantum experiments for the measurement of residual dipolar couplings (Dres), the application of the Carr–Purcell–Meiboom–Gill pulse sequence for the measurement of the transverse magnetization decay and the extraction of 1H T2 relaxation times, and the use of field cycling NMR relaxometry for the determination of T1 relaxation times. The microscopic properties determined by TD-NMR experiments were discussed in comparison with the macroscopic properties obtained using equilibrium swelling, moving die rheometer, and calorimetric techniques. The obtained correlations between NMR observables, crosslink density values, maximum torque values, and glass transition temperatures provided insights into the effects of the vulcanization temperature and accelerator/sulfur ratio on the structure of the polymer networks, as well as on the effects of crosslinking on the segmental dynamics of elastomers. Dres and T2 were found to show linear correlations with the crosslink density determined by equilibrium swelling, while T1 depends on the local dynamics of polymer segments related to the glass transition, which is also affected by chemical modifications of the polymer chains occurring during vulcanization.

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Influence of sulfur content and curing time on the glass transition parameters in SBR vulcanizates: an ultrasonic study

Cited by 14 publications

References 25 publications

Ultrasonic and dielectric relaxations in PDMS/ZnO nanocomposite

Ultrasonic and dielectric relaxations in PDMS/ZnO nanocomposite

Dielectric properties of polydimethylsiloxane composites filled with SrTiO₃ nanoparticles

Influence of Sulfur-Curing Conditions on the Dynamics and Crosslinking of Rubber Networks: A Time-Domain NMR Study

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Influence of sulfur content and curing time on the glass transition parameters in SBR vulcanizates: an ultrasonic study

Cited by 14 publications

References 25 publications

Ultrasonic and dielectric relaxations in PDMS/ZnO nanocomposite

Ultrasonic and dielectric relaxations in PDMS/ZnO nanocomposite

Dielectric properties of polydimethylsiloxane composites filled with SrTiO3 nanoparticles

Influence of Sulfur-Curing Conditions on the Dynamics and Crosslinking of Rubber Networks: A Time-Domain NMR Study

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Dielectric properties of polydimethylsiloxane composites filled with SrTiO₃ nanoparticles