Abstract
High breakdown strength and low dielectric loss are necessary for the outdoor insulator using silicone rubber (SR) composites. In this work, polydopamine coated mica (mica-PDA) was synthesized via bioinspired dopamine self-polymerization, and mica-PDA-filled SR composite (SR/mica-PDA-VTMS) was prepared using vinyl tri-methoxysilane (VTMS) as a silane coupling agent which serves as the molecular bridges between the organic rubber and the inorganic filler. The SR/mica-PDA-VTMS composite demonstrated dense and uniform morphology where the filler was well dispersed. Due to the strong interfacial interactions between filler and rubber, the SR/mica-PDA-VTMS composite exhibits much lower dielectric loss compared to the other mica-filled SR composites, which was comparable to the prepared alumina-tri-hydrate-filled SR composites. Moreover, the breakdown strength of ~31.7 kV/mm and tensile strength of 5.4 MPa were achieved for the SR/mica-PDA-VTMS composite, much higher than those of the other as-prepared SR composites.
Highlights
Silicone rubber (SR) has been widely used in high-voltage outdoor insulation due to the excellent hydrophobicity and weather-resistance [1,2,3]
Polydopamine was coated on theon surface of mica of to provide
Mica was coated with polydopamine to introduce a large number of hydroxyl groups that react more with the silane coupling agent
Summary
Silicone rubber (SR) has been widely used in high-voltage outdoor insulation due to the excellent hydrophobicity and weather-resistance [1,2,3]. As for SR composites applied in high-voltage insulation, the breakdown strength and dielectric loss are the two most important properties. Mica is a natural mineral composed of a layered silicate structure with excellent electrical insulating properties, which has played a role as the reinforcement filler in different types of polymer composites [11,12,13]. Silane coupling agents are the most popular surface modifier for the inorganic filler to improve the compatibility between the hydrophilic filler and hydrophobic. The active sites on the mica surface that could react with silane coupling agents are relatively few. Mica was first coated with polydopamine to obtain mica-PDA, rendering mica with a large number of hydroxyl groups which react more with the silane coupling agent. Mica-PDA-filled SR composites (SR/mica-PDA-VTMS) were prepared with mica-PDA as a filler and with vinyl tri-methoxysilane (VTMS) as a silane coupling agent. Some other SR composites were prepared and investigated to reveal the structure–property relationship of these
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