The dielectric breakdown limit of silicone dielectric elastomer actuators

Gatti, Davide; Haus, Henry; Matysek, Marc; Frohnapfel, Bettina; Tropea, Cameron; Schlaak, Helmut F.

doi:10.1063/1.4863816

Cited by 93 publications

(76 citation statements)

References 24 publications

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“…It is well known that the electrical breakdown performance of dielectric elastomers is influenced strongly by material conditions such as the Young's modulus, 21 applied pre-strain 20,22-24 and elastomer thickness. 22,24 Electrical breakdown strength values remain constant within experimental uncertainty, irrespective of the concentration of the added ionic network, the presence of which in the investigated concentrations therefore does not affect the overall breakdown strength of the materials.…”

Section: Self-healing High-permittivity Silicone Dielectric Elastomermentioning

confidence: 98%

Self-Healing, High-Permittivity Silicone Dielectric Elastomer

2016

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Currently used dielectric elastomers do not have the ability to self-heal after detrimental events such as tearing or electrical breakdown, which are critical issues in relation to product reliability and lifetime. In this paper, we present a self-healing dielectric elastomer that additionally possesses high dielectric permittivity and consists of an interpenetrating polymer network of silicone elastomer and ionic silicone species that are cross-linked through proton exchange between amines and acids. The ionically cross-linked silicone provides self-healing properties after electrical breakdown or cuts made directly to the material due to the reassembly of the ionic bonds that are broken during damage. The dielectric elastomers presented in this paper pave the way to increased lifetimes and the ability of dielectric elastomers to survive millions of cycles in high-voltage conditions.

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Section: Self-healing High-permittivity Silicone Dielectric Elastomermentioning

confidence: 98%

Self-Healing, High-Permittivity Silicone Dielectric Elastomer

2016

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“…Electromechanical pull-in instability, also known as electromechanical instability (EMI), was identified by Stark and Garton [9] and occurs when 2 Maxwell pressure locally exceeds the compressive stress of the elastomer [4,10]. For silicone elastomers, mechanical strength failure is very seldom a failure mode, due to the ultimate extensibility of silicone elastomers usually exceeding 300%.…”

Section: Introductionmentioning

confidence: 99%

“…Maxwell pressure locally exceeds the compressive stress of the elastomer [4,10]. For silicone elastomers, mechanical strength failure is very seldom a failure mode, due to the ultimate extensibility of silicone elastomers usually exceeding 300%.…”

Section: Introductionmentioning

confidence: 99%

The influence of static pre-stretching on the mechanical ageing of filled silicone rubbers for dielectric elastomer applications

Zakaria

Kofod³

et al. 2015

Materials Today Communications

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Dielectric elastomer (DE) pre-stretching is a key aspect of attaining better actuation performance, as it helps prevent electromechanical instability (EMI) and usually lowers the Young's modulus, thus leading to easier deformation. The pre-stretched DE is not only susceptible to a high risk of tearing and the formation of mechanical defects, but films with sustained and substantial strain may also experience mechanical degradation. In this study a long-term mechanical reliability study of DE is performed. Young's moduli, dielectric breakdown strengths and dielectric permittivities of commercial silica-reinforced silicone elastomers, with and without an additional 35% (35 phr) of titanium dioxide (TiO 2 ), were investigated after being subjected to pre-stretching for various timespans at pre-stretches to strains of 60 and 120%, respectively. The study shows that mechanical stability when prestretching is difficult to achieve with highly filled elastomers. However, despite the negative outlook for metal oxide-filled silicone elastomers, the study paves the way for reliable dielectric elastomers by indicating that simply post-curing silicone elastomers before use may increase reliability. 1 INTRODUCTIONThe reliability of dielectric elastomer (DE) transducers depends on the types of material used, as well as fabrication techniques and design and transducer operating conditions (such as maximum stretching, applied frequency and amplitude of the applied voltage). The acrylic double-adhesive VHB 4910, produced by 3M, is one of the best-performing elastomers with respect to actuation strain (s) at a given applied field, and it chiefly outperforms silicone-based elastomers over short time scales. Silicone elastomers, however, possess a faster actuation response as well as reliability over time, since performance remains more or less unaltered up to about 10 million cycles when pre-stretching is avoided.[1] Pre-stretching is well-known to be a prerequisite for the actuation of acrylic-based elastomers, since it simultaneously reduces thickness, decreases the Young's modulus and suppresses electro-mechanical instability (EMI). Pre-stretching has also been shown to cause the alignment of elastomer chains in the plane of stretching.[5] This alignment, which is perpendicular to the direction of the electric field, leads to an increase in breakdown strength, because charge carrier movement is impeded.[6] For acrylics, pre-stretching is also favourable due to strain-softening, whereas for silicone elastomers the elastomer usually does not show the same tendency and in many cases strain-hardening behaviour actually sets in. However, pre-stretching remains very favourable for silicone elastomers, as largely improved actuation strains can be obtained through the avoidance of EMI.The most common failure modes of DE transducers are pull-in instability, dielectrical breakdown and material strength failure [7,8]. Electromechanical pull-in instability, also known as electromechanical instability (EMI), was identified by Stark a...

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“…Most dielectric enhancement methods introduce a reduction in the electrical breakdown strength and therefore the elastomers from such methods will need to be operated at a lower voltage for reliability. This is unfavorable but at the current stage of dielectric elastomer development the electrical breakdown processes are not fully understood 18,19 . So as such there exists no guideline on how to formulate elastomers with high electrical breakdown strength except the generic guidelines on what to avoid such as percolation of fillers etc 20,21 .…”

Section: Introductionmentioning

confidence: 99%

Electrical breakdown phenomena of dielectric elastomers

Mateiu

Skov

2017

SPIE Proceedings

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Silicone elastomers have been heavily investigated as candidates for dielectric elastomers and are as such almost ideal candidates with their inherent softness and compliance but they suffer from low dielectric permittivity. This shortcoming has been sought optimized by many means during recent years. However, optimization with respect to the dielectric permittivity solely may lead to other problematic phenomena such as premature electrical breakdown. In this work, we investigate the electrical breakdown phenomena of various types of permittivity-enhanced silicone elastomers. Two types of silicone elastomers are investigated and different types of breakdown are discussed. Furthermore the use of voltage stabilizers in silicone-based dielectric elastomers is investigated and discussed.

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The dielectric breakdown limit of silicone dielectric elastomer actuators

Cited by 93 publications

References 24 publications

Self-Healing, High-Permittivity Silicone Dielectric Elastomer

Self-Healing, High-Permittivity Silicone Dielectric Elastomer

The influence of static pre-stretching on the mechanical ageing of filled silicone rubbers for dielectric elastomer applications

Electrical breakdown phenomena of dielectric elastomers

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