Effect of treated mica on rheological, cure, mechanical, and dielectric properties of ethylene propylene diene monomer (EPDM)/barium titanate (BaTiO₃)/mica

In this study, mica, treated by three types of coupling agents, isopropyl trioleic titanate (NDZ105), 3-aminopropyltriethoxysilane (KH550), and vinyltrimethoxysiloxane homopolymer (SG-Si6490), were utilized to improve the properties of ethylene propylene diene monomer (EPDM)/barium titanate (BaTiO₃) composites. It is found that the addition of untreated mica can increase the complex viscosity, while the KH550 modified mica can reduce the complex viscosity. Compared to single usage of coupling agent SG-Si6490, the hybrid usage of KH550 and SG-Si6490 can further increase the tensile strength of EPDM/BaTiO₃/SG-Si6490 treated mica (70/20/10) from 9.10 to 11.01 MPa (22% increase). The untreated mica can increase the interfacial polarity and improve the dielectric constant of EPDM/BaTiO₃ (70/30) from 7 to 9 at 40 MHz (28% increase). Moreover, the KH550 treated mica can enhance the thermal conductivity of EPDM/BaTiO₃ (70/30) from 0.323 W m⁻¹ K⁻¹ to 0.446 W m⁻¹ K⁻¹ (38% increase). In the meantime, the increased crosslink density caused by coupling agents can increase the volume resistivity of EPDM composites.