Actuator Performance of a Hydrogenated Carboxylated Acrylonitrile–Butadiene Rubber/Silica-Coated BaTiO₃ Dielectric Elastomer

Abstract

We synthesized silica-coated barium titanate (BaTiO 3 ) particles with different silica shell thicknesses and evaluated the effect of silica coating on the relative dielectric properties of silica-coated BaTiO 3 particles. Furthermore, composite elastomers were prepared using hydrogenated carboxylated acrylonitrile−butadiene rubber (HXNBR) with a high relative dielectric constant (ε r ) and silica-coated BaTiO 3 particles, and their performance as an actuator was evaluated. Both ε r and relative dielectric loss of non-coated BaTiO 3 particles increased at low frequencies (<200 Hz) associated with ionic conduction. However, ε r and relative dielectric loss were reduced for the silica-coated BaTiO 3 particles with thick silica shells, indicating that silica coating reduced ion migration. The dielectric breakdown strength increased with the thickness of the silica shell; it increased up to 80 V/μm for HXNBR/silica-coated BaTiO 3 particles with 20 nm-thick silica shells. The maximum generated stress, strain, and output energy density of the composite elastomer with HXNBR (with a high relative constant) and silica-coated BaTiO 3 were 1.0 MPa, 7.7%, and 19.4 kJ/m 3 , respectively. In contrast, the values of the same parameters for a reference elastomer (acrylic/BaTiO 3 ; with low ε r ) were 0.4 MPa, 6.7%, and 6.8 kJ/m 3 at the dielectric breakdown strength of 70 V/μm. The results indicated that the elastomers composed of HXNBR and silica-coated BaTiO 3 exhibited higher generated stress, strain, and output energy density than elastomers for conventional dielectric actuators.

Improved electrical actuation and dielectric strength of rubber composites with polydopamine noncovalent and silane covalent modification of carbon nanotube

“…However, the poor compatibility between the conductive filler and the polymeric matrix usually introduces many defects and voids into the dielectric composites, leading to decreased dielectric strength and increased dielectric loss tangent (tan ⊐). 21 Therefore, coating an insulation layer on the surface of a conductive filler is usually employed to prevent the conductive filler from forming a conductive network in the polymeric matrix. 22,23 Wei et al 24 utilized hyperbranched polysiloxane (HPSi) to modify layered Ti 3 C 2 T x sheets (HPSi-d-Ti 3 C 2 T x ), which were then dispersed into a PDMS matrix to produce bimodal-network dielectric composites (HPSi-d-Ti 3 C 2 T x /PDMS).…”

“…In addition, the maximum planar actuation strain at 20 kV mm −1 was calculated and was noticeably enhanced from 5.07% for PDMS/GO composites to 12.87% for PDMS/rGO‐400 composites. However, the poor compatibility between the conductive filler and the polymeric matrix usually introduces many defects and voids into the dielectric composites, leading to decreased dielectric strength and increased dielectric loss tangent (tan δ ) 21 . Therefore, coating an insulation layer on the surface of a conductive filler is usually employed to prevent the conductive filler from forming a conductive network in the polymeric matrix 22, 23 .…”