One prominent method of modifying the properties of dielectric elastomers(DEs)is by adding suitable metal oxide fillers.However,almost all commercially available sili-cone elastomers are already heavily filled with si...One prominent method of modifying the properties of dielectric elastomers(DEs)is by adding suitable metal oxide fillers.However,almost all commercially available sili-cone elastomers are already heavily filled with silica to reinforce the otherwise rather weak silicone network and the resulting metal oxide filled elastomer may contain too much filler.We therefore explore the replacement of silica with titanium dioxide to ensure a relatively low concentration of filler.Liquid silicone rubber(LSR)has relatively low viscosity,which is favorable for loading inorganic fillers.In the present study,four commercial LSRs with varying loadings of silica and one benchmark room-temperature vulcanizable rubber(RTV)were investigated.The resulting elastomers were evaluated with respect to their dielectric permittivity,tear and tensile strengths,electrical breakdown,thermal stability and dynamic viscosity.Filled silicone elasto-mers with high loadings of nano-sized titanium dioxide(TiO_(2))particles were also studied.The best overall performing formulation had 35 wt.%TiO_(2) nanoparticles in the POWERSIL®XLR LSR,where the excellent ensemble of relative dielectric permittivity of 4.9 at 0.1 Hz,breakdown strength of 160 V µm^(−1),tear strength of 5.3 MPa,elongation at break of 190%,a Young’s modulus of 0.85 MPa and a 10% strain response(simple tension)in a 50 Vμm^(−1) electric field was obtained.展开更多
Silicone foams with and without liquid fillers(silicone oils of various types and glycerol,respectively)are synthesized and analyzed to be used as dielectric layers in capacitive sensors.A simple fabrication technique...Silicone foams with and without liquid fillers(silicone oils of various types and glycerol,respectively)are synthesized and analyzed to be used as dielectric layers in capacitive sensors.A simple fabrication technique involving only four components i.e.Sylgard 184,glycerol,sodium hydroxide and ethanol is used to make these silicone foams after which they are filled with silicone oil or glycerol by soaking the foam in respective liquid.Mechanical and dielectric properties of the foams are examined.The oil reinforces the foam’s dielectric properties,softens the foam and improves its capacitive response,making it a very good dielectric material for fabricating capacitive pressure sensors.Compared to dry silicone foams,foams filled with-and swollen by-chloropropyl-functional silicone oil,show a low Young’smodulus(31 kPa),a high and stable relative dielectric permittivity of around 5,and a high capacitive response of 132%for an appliedpressureof 12 kPa.Thepresence of oil stabilizes the soft foam and ensures that it does not buckle under high pressure.展开更多
A large number of insulation/dielectric failures in power systems are related to thermally-induced dielectrical breakdown,also known as‘thermal breakdown’,at higher operating temperatures.In this work,the thermal br...A large number of insulation/dielectric failures in power systems are related to thermally-induced dielectrical breakdown,also known as‘thermal breakdown’,at higher operating temperatures.In this work,the thermal breakdown behavior of typical silicone formulations,used as dielectrics in stretchable electronic devices,is analyzed at practically relevant operating temperatures ranging from 20℃ to 80℃.An effective way of delaying the thermal breakdown of insulating materials is to blend micro-or nano-sized inorganic particles with high thermal conductivity,to dissipate better any losses generated during energy transduction.Therefore,two types of commercial silicone formulations,blended with two types of rutile hydrophobic,high-dielectric TiO_(2) fillers,are investigated in relation to their dielectric properties,namely,relative permittivity,the dissipation factor,and electrical breakdown strength.The breakdown strengths of these silicone composites are subsequently evaluated using Weibull analysis,which indicates a negative correlation between temperature and shape parameter for all compositions,thus illustrating that the homogeneity of the samples decreases in line with temperature,but the breakdown strengths nevertheless increase initially due to the trapping effect from the high-permittivity fillers.展开更多
基金The authors gratefully acknowledge the financial support of InnovationsFonden.
文摘One prominent method of modifying the properties of dielectric elastomers(DEs)is by adding suitable metal oxide fillers.However,almost all commercially available sili-cone elastomers are already heavily filled with silica to reinforce the otherwise rather weak silicone network and the resulting metal oxide filled elastomer may contain too much filler.We therefore explore the replacement of silica with titanium dioxide to ensure a relatively low concentration of filler.Liquid silicone rubber(LSR)has relatively low viscosity,which is favorable for loading inorganic fillers.In the present study,four commercial LSRs with varying loadings of silica and one benchmark room-temperature vulcanizable rubber(RTV)were investigated.The resulting elastomers were evaluated with respect to their dielectric permittivity,tear and tensile strengths,electrical breakdown,thermal stability and dynamic viscosity.Filled silicone elasto-mers with high loadings of nano-sized titanium dioxide(TiO_(2))particles were also studied.The best overall performing formulation had 35 wt.%TiO_(2) nanoparticles in the POWERSIL®XLR LSR,where the excellent ensemble of relative dielectric permittivity of 4.9 at 0.1 Hz,breakdown strength of 160 V µm^(−1),tear strength of 5.3 MPa,elongation at break of 190%,a Young’s modulus of 0.85 MPa and a 10% strain response(simple tension)in a 50 Vμm^(−1) electric field was obtained.
基金supported by the China Scholarship CouncilTeknologi og Produktion,Det Frie Forskningsrad。
文摘Silicone foams with and without liquid fillers(silicone oils of various types and glycerol,respectively)are synthesized and analyzed to be used as dielectric layers in capacitive sensors.A simple fabrication technique involving only four components i.e.Sylgard 184,glycerol,sodium hydroxide and ethanol is used to make these silicone foams after which they are filled with silicone oil or glycerol by soaking the foam in respective liquid.Mechanical and dielectric properties of the foams are examined.The oil reinforces the foam’s dielectric properties,softens the foam and improves its capacitive response,making it a very good dielectric material for fabricating capacitive pressure sensors.Compared to dry silicone foams,foams filled with-and swollen by-chloropropyl-functional silicone oil,show a low Young’smodulus(31 kPa),a high and stable relative dielectric permittivity of around 5,and a high capacitive response of 132%for an appliedpressureof 12 kPa.Thepresence of oil stabilizes the soft foam and ensures that it does not buckle under high pressure.
基金supported by the Independent Research Fund Denmark.
文摘A large number of insulation/dielectric failures in power systems are related to thermally-induced dielectrical breakdown,also known as‘thermal breakdown’,at higher operating temperatures.In this work,the thermal breakdown behavior of typical silicone formulations,used as dielectrics in stretchable electronic devices,is analyzed at practically relevant operating temperatures ranging from 20℃ to 80℃.An effective way of delaying the thermal breakdown of insulating materials is to blend micro-or nano-sized inorganic particles with high thermal conductivity,to dissipate better any losses generated during energy transduction.Therefore,two types of commercial silicone formulations,blended with two types of rutile hydrophobic,high-dielectric TiO_(2) fillers,are investigated in relation to their dielectric properties,namely,relative permittivity,the dissipation factor,and electrical breakdown strength.The breakdown strengths of these silicone composites are subsequently evaluated using Weibull analysis,which indicates a negative correlation between temperature and shape parameter for all compositions,thus illustrating that the homogeneity of the samples decreases in line with temperature,but the breakdown strengths nevertheless increase initially due to the trapping effect from the high-permittivity fillers.
