Influence of SiO2 fillers on the irradiation ageing of silicone rubbers

Stevenson, Isabelle; David, Laurent; Gauthier, Catherine; Arambourg, L.; Davenas, J.; Vigier, G.

doi:10.1016/s0032-3861(01)00470-0

Cited by 93 publications

(58 citation statements)

References 13 publications

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“…Irradiation ageing has previously been studied by Stevenson et al [28], but during such experiments crosslinking density changed, whereas in this study crosslink density remains constant.…”

Section: Introductionmentioning

confidence: 88%

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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“…Irradiation ageing has previously been studied by Stevenson et al [28], but during such experiments crosslinking density changed, whereas in this study crosslink density remains constant.…”

Section: Introductionmentioning

confidence: 88%

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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“…Over extended dose ranges the competition between these overlapping reactions can, however, lead to nonlinear behavior. 1,2,4,6,17 Unfortunately, the specific changes in the dominating mechanisms that may be responsible for this variance, particularly in radiation induced degradation, is generally poorly understood. This is due in no small part to a lack of methodologies that provide correlation between changes in chemical speciation and the remaining composite network structure that determine the engineering properties.…”

Section: Spectrometry (Gc/ms) the Mechanical Data Andmentioning

confidence: 99%

MQ NMR and SPME Analysis of Nonlinearity in the Degradation of a Filled Silicone Elastomer

et al. 2010

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Radiation-induced degradation of polymeric materials occurs through numerous, simultaneous, competing chemical reactions. Although degradation is typically found to be linear in adsorbed dose, some silicone materials exhibit nonlinear dose dependence due to dose-dependent dominant degradation pathways. We have characterized the effects of radiative and thermal degradation on a model filled-PDMS system, Sylgard 184 (commonly used in electronic encapsulation and in biomedical applications), using traditional mechanical testing, NMR spectroscopy, and sample headspace analysis using solid-phase microextraction (SPME) followed by gas chromatography/mass spectrometry (GC/MS). The mechanical data and 1H spin−echo NMR spectra indicated that radiation exposure leads to predominantly cross-linking over the cumulative dose range studied (0−250 kGy) with a rate roughly linear with dose. 1H multiple-quantum NMR spectroscopy detected a bimodal distribution in the network structure, as expected from the proposed structure of Sylgard 184. The MQ NMR spectra further indicated that the radiation-induced structural changes were not linear in adsorbed dose and that competing chain scission mechanisms made a greater contribution to the overall degradation process in the range of 50−100 kGy (although cross-linking still dominated). The SPME−GC/MS data were analyzed using principal component analysis (PCA), which identified subtle changes in the distributions of degradation products (the cyclic siloxanes and other components of the material) as a function of age that provide insight into the dominant degradation pathways at low and high adsorbed dose.

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“…Very few studies were devoted to the irradiation effect on silica filled rubbers, and they mainly focused on PDMS filled silica systems [8,9,10,11,12]. To our knowledge no study concerns the ageing of nanoscopic silica filled (EPDM).…”

Section: Introductionmentioning

confidence: 99%

“…When introducing silica in EPDM, the created filler-matrix interactions are very different from those found in silica filled PDMS: there are not strong hydrogen bonds between silica and the matrix. Moreover, in silica/PDMS system, it was shown that covalent bonds are formed at the interface during irradiation [8]. Therefore, the chemistry of the system as well as the initial polymer-filler interaction (van der Waals interaction) being very different in silica-filled EPDM, the consequences of ageing under irradiation could be very different from those found with silica filled PDMS systems.…”

Section: Introductionmentioning

confidence: 99%

Influence of silica fillers on the ageing by gamma radiation of EDPM nanocomposites

Planès

Chazeau

Vigier

et al. 2010

Composites Science and Technology

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Abstract:This study evidences that the presence of silica fillers as well as their surface treatment influences the impact of gamma irradiation on the mechanical properties of the filled materials. It influences it both chemically, by a modification of the kinetics of the degradation reactions, and physically, through the complex modification of the filler-filler and fillermatrix interactions involved in the mechanical properties of the filler network.

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Influence of SiO2 fillers on the irradiation ageing of silicone rubbers

Cited by 93 publications

References 13 publications

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

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

MQ NMR and SPME Analysis of Nonlinearity in the Degradation of a Filled Silicone Elastomer

Influence of silica fillers on the ageing by gamma radiation of EDPM nanocomposites

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