Improved electromechanical properties of brominated butyl rubber filled with modified barium titanate

Abstract

In order to improve the compatibility between barium titanate (BT) particles and a brominated butyl rubber (BIIR) matrix, a silane coupling agent γ-methacryloxy propyl trimethoxysilane (KH570) was used to modify the BT particles. Subsequently, BT and the BT-KH570 particles were added into the BIIR matrix to form BT/BIIR and BT-KH570/BIIR dielectric composites. The BT-KH570/BIIR composite has a higher dielectric constant, better mechanical properties, and larger actuated strain compared with the BT/BIIR composite with the same filler content. The 10 phr BT-KH570/BIIR composite achieved the largest actuated strain. To further increase the actuated strain of the BT-KH570/BIIR composite, the polar plasticizer tri-n-butyl phosphate (TBP) was added into the composite. Due to the polar groups of TBP, the dielectric constant of the TBP/BT-KH570/BIIR composite was improved and the elastic modulus decreased at the same time. As a result, we obtained a gain in actuated strain of 4.46% at an electric field of 22.5 kV mm⁻¹, which corresponds to an increase of about 500% in comparison with that of pure BIIR. This represents a significant improvement in actuated strain performance.