Determination of young's modulus of elastomers by use of a thermomechanical analyzer

Hwo, Chiu‐Hsiung; Johnson, Julian F.

doi:10.1002/app.1974.070180514

Cited by 18 publications

(10 citation statements)

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“…The uniaxial compression modulus [5,6] .K/ is given by equation (2), where a is the radius of the contact zone between the probe and the sealant, P is the load on the probe, and R is the radius of the probe tip.…”

Section: Young's Modulusmentioning

confidence: 99%

Kinetics of cure, cross link density and adhesion of water-reactive alkoxysilicone sealants

Buyl¹,

Comyn²,

Shephard³

et al. 2002

Journal of Adhesion Science and Technology

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When a silicone sealant is exposed to wet air, a surface skin is formed, which becomes thicker with time. For a 1-part room temperature vulcanization (1-RTV), neutral cure system based on the hydrolysis and condensation reactions of alkoxysilanes, it has been observed that, at constant temperature and humidity, the thickness of the cured layer is initially proportional to the square root of time, but later the gradient of such a plot increases. There are thus two regions of cure, an outer region and an inner one. Swelling in toluene, which has been measured for samples taken at various depths, shows that the cross link density is greater in the outer regions. Single lap joints of aluminium or glass have been cured in these two regions and joints from the outer region are always stronger than the corresponding ones from the inner region. This behaviour has been ascribed to the mobility of low molar mass cross linking and coupling agents. During the initial stages of cure they migrate into the outer region, but once cure has passed into the inner region there is now a paucity of these compounds. Young's modulus and the concentration pro le of silane crosslinking agent have also been measured. All observations con rm migration of crosslinking species, and gradient formation for most physical properties in the nal joint.Measurement of the water vapour permeability coef cient .P / of the cured siloxane network has shown that P is independent of humidity and stretching of the material. A plot of log P against reciprocal absolute temperature is non-linear with positive slope, showing that the heat of permeation is negative and varies with temperature. This can be explained by the formation of water-clusters. When the network is formed water is absorbed and alcohol is released.

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Section: Young's Modulusmentioning

confidence: 99%

Kinetics of cure, cross link density and adhesion of water-reactive alkoxysilicone sealants

Buyl¹,

Comyn²,

Shephard³

et al. 2002

Journal of Adhesion Science and Technology

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“…From Figure 6, we can see that at each temperature the strain increases with voltage as expected, and that at each voltage the actuation strain is higher at lower temperature; this trend is more pronounced at higher voltage. This variation of actuation strain with temperature is likely related to the dependence of an elastomer's modulus with temperature [28]. Since the elasticity of an elastomer is driven by entropy, the modulus will decrease with decreasing temperature.…”

Section: Broad Actuation Temperature Range Of Siliconementioning

confidence: 99%

Fault-tolerant silicone dielectric elastomers

Yuan

Brochu

et al. 2010

International Journal of Smart and Nano Materials

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Soft silicone films have garnered a great deal of interest for use in dielectric elastomer transducers due to their excellent properties, including high elongation to rupture, low viscoelasticity, and broad application temperature range. However, silicone films generally have higher stiffness and lower dielectric strength than VHB acrylic elastomers, which limits the achievable actuation strain. Devices based on silicone dielectric elastomers always experience high rates of premature dielectric failure when operated at high strains. The premature failure is characterized by the loss of functionality or mechanical rupture of the material when operated below the material's dielectric strength and elongation to rupture. The use is reported of ultrathin coatings of single-walled carbon nanotubes (SWNTs) as the compliant electrodes, which can overcome the issue of premature failure. The self-clearing of the SWNT electrodes in the event of localized dielectric breakdown improves the apparent dielectric strength of the material by isolating the regions of reduced dielectric strength. The actuators may be operated at higher than 50% area strain with reasonably long lifetimes. High strains were measured between -40 and 80 C and in a broad frequency range up to 100 Hz. The fault tolerance introduced by the SWNT electrodes should broaden the application scope of silicone dielectric elastomers.

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“…Despite the noise in the stress data at low strains, it is possible roughly estimate the Young's modulus in the linear regime for 75 n 100: E ~ 0.01 GPa (see Fig. S12 in the SI), a value that is comparable to silicone elastomer (E ~ 0.011 GPa) [53] and Ethylene vinyl Acetate (EVA) copolymers (E ~ 0.012 GPa) [54]. The stress-strain curves show that as the strand length increases, the Young's modulus decreases slightly, indicating that the network becomes more elastic and softer.…”

Section: Influence Of Chain Length On the Stress-strain Relationmentioning

confidence: 99%

“…The Young's moduli of Tetra-PE systems and different polymer materials (a: [64], b: [54] and c: [53] Figure S2 Local order ! probability distribution for the n-eicosane system with a half-crystal, half-melt configuration.…”

Section: Table S6mentioning

confidence: 99%

Mechanical Properties of Tetrapolyethylene and Tetrapoly(ethylene oxide) Diamond Networks via Molecular Dynamics Simulations

Wang

Escobedo

2016

Macromolecules

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The tensile response to uniaxial deformation of polyethylene-based (Tetra-PE) and polyethylene glycol-based (Tetra-PEG) networks of various strand lengths with idealized diamond connectivity have been studied via atomistic molecular dynamics simulations. Tetra-PE and Tetra-PEG diamond networks with the same strand length show comparable maximum extensibility but the Young's moduli and tensile strength of the former are significantly lower than those of the latter, consistent with stronger intersegmental attractions in the amorphous Tetra-PEG networks. The stress-strain curves show that the stress in short-stranded networks increased rapidly and monotonically with strain while for long-stranded networks it increased very little at small strain, in a non-monotonic fashion at intermediate strains, and then very sharply as the limit of extensibility was approached. Spontaneous partial crystallization of a long-stranded Tetra-PE diamond network under supercooling was demonstrated, and the resulting system was used to: (1) Estimate its melting point as the temperature where any crystalline material disappeared abruptly, and (2) show that the presence of crystalline material in the undeformed state leads to higher stress responses upon deformation compared to amorphous samples, a result consistent with experimental observations. The spontaneous crystallization of Tetra-PEG networks at large supercooling was unsuccessful due to the slow motions of the network beads and the prohibitively long crystal nucleation times entailed.iii BIOGRAPHICAL SKETCHThe author, Endian Wang, born in Fujian, China, attended his middle school and high school in He studied and enjoyed sketching and oil painting during middle school and high school, and would like to continue painting in the near future.iv ACKNOWLEDGEMENTS

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Determination of young's modulus of elastomers by use of a thermomechanical analyzer

Cited by 18 publications

References 0 publications

Kinetics of cure, cross link density and adhesion of water-reactive alkoxysilicone sealants

Kinetics of cure, cross link density and adhesion of water-reactive alkoxysilicone sealants

Fault-tolerant silicone dielectric elastomers

Mechanical Properties of Tetrapolyethylene and Tetrapoly(ethylene oxide) Diamond Networks via Molecular Dynamics Simulations

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