Structure Characterization in the Science and Technology of Elastomers

Roland, C. M.

doi:10.1016/b978-0-12-394584-6.00003-0

Cited by 4 publications

(7 citation statements)

References 275 publications

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“…Typical stress-strain behaviour with the strain rate of 0.024 s −1 is shown in figure 1, after five cycles from which the hysteresis becomes stable. The mechanical hysteresis originates from SIC [26][27][28], and the stress upturn during the strain increase process is typical from the stress hardening effect of SIC. Contrarily, the lower stress during the retraction process is due to a larger degree of SIC, indicating that the stress relaxation effect of SIC dominates in this process.…”

Section: Methodsmentioning

confidence: 99%

Fatigue effect of elastocaloric properties in natural rubber

Sebald¹,

Xie²,

Guyomar³

2016

Phil. Trans. R. Soc. A.

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In the framework of elastocaloric (eC) refrigeration, the fatigue effect on the eC effect of natural rubber (NR) is investigated. Repetitive deformation cycles at engineering strain regime from 1 to 6 results in a rapid rupture (approx. 800 cycles). Degradation of properties and fatigue life are then investigated at three different strain regimes with the same strain amplitude: before onset strain of strain-induced crystallization (SIC) (strain regime of 0-3), onset strain of melting (strain regime of 2-5) and high strain of SIC (strain regime of 4-7). Strain of 0-3 leads to a low eC effect and cracking after 2000 cycles. Strain of 2-5 and 4-7 results in an excellent crack growth resistance and much higher eC effect with adiabatic temperature changes of 3.5 K and 4.2 K, respectively, thanks to the effect of SIC. The eC stress coefficient index γ (ratio between eC temperature change and applied stress) for strains of 2-5 and 4-7 are γ2-5=4.4 K MPa(-1) and γ4-7=1.6 K MPa(-1), respectively, demonstrating the advantage of the strain regime 2-5. Finally, a high-cycle test up to 1.7×10(5) cycles is successfully applied to the NR sample with very little degradation of eC properties, constituting an important step towards cooling applications.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'.

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Section: Methodsmentioning

confidence: 99%

Fatigue effect of elastocaloric properties in natural rubber

Sebald¹,

Xie²,

Guyomar³

2016

Phil. Trans. R. Soc. A.

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“…(1) Elastomers are very viscous compared to plastics due to their very high molecular weights, up to 1 million g/mol [5]. This higher viscosity makes the dispersion of conductive fillers much more difficult than that in plastics.…”

Section: Introductionmentioning

confidence: 99%

“…This higher viscosity makes the dispersion of conductive fillers much more difficult than that in plastics. (2) Elastomers are essentially amorphous and thus do not exhibit selective dispersion induced by crystallization [5,6]. (3) Elastomers are thermosetting polymers.…”

Section: Introductionmentioning

confidence: 99%

Transport performance in novel elastomer nanocomposites: Mechanism, design and control

Guo

Tang

Zhang

2016

Progress in Polymer Science

138

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“…However, when the material is strained, the chains begin to align, creating negative pressure regions that draw the NiNs closer together (see Fig. 9) [36].…”

Section: Junction Distancementioning

confidence: 98%

“…Sylgard 184 is mainly composed of polydimethylsiloxane (PDMS), a silicone polymer with simple functional groups that have relatively little interaction with each other and generally do not have cross-linking capabilities [35]. Since the polymer can only bond at its end functional groups, there is no covalent chemical interaction between the densely packed nickel crystalline form and the polymer net that grows to encase it [36]. Without bonds between the nickel and the silicone, the strands of nickel are simply surrounded in a flexible network which allows limited translational and rotational motion.…”

Section: Junction Distancementioning

confidence: 99%

Evolution of nano-junctions in piezoresistive nanostrand composites

Bilodeau

Fullwood

Colton

et al. 2015

Composites Part B: Engineering

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a b s t r a c tWhen nickel nanostrands (NiNs) are embedded inside of highly flexible silicone, the silicone becomes an extremely piezoresistive sensor capable of measuring a large dynamic range of strains. These sensors experience an increase in conductance of several orders of magnitude when strained to 40% elongation. It has been hypothesized that this effect stems from a net change in average junction distance between the conductive particles when the overall material is strained. The quantum tunneling resistance across these gaps is highly sensitive to junction distance, resulting in the immense piezoresistive effect. In this paper, the average junction distance is monitored using dielectric spectroscopy while the material is strained. By incorporating new barrier height measurements of the base silicone material from a nanoindentation experiment, this experiment validates previous assumptions that, on average, the junctions between NiNs decrease while the sample is strained, instigating the large piezoresistive effect. The nature of the material's response to strain is explored and discussed.

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Structure Characterization in the Science and Technology of Elastomers

Cited by 4 publications

References 275 publications

Fatigue effect of elastocaloric properties in natural rubber

Fatigue effect of elastocaloric properties in natural rubber

Transport performance in novel elastomer nanocomposites: Mechanism, design and control

Evolution of nano-junctions in piezoresistive nanostrand composites

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