In this work, TiO₂ nanofibers (TiO₂ NFs) with micron-nano size are prepared via electrospinning, and composites with TiO₂ nanoparticles (TiO₂ NPs) and TiO₂ NFs as fillers are prepared using EPDM as the matrix. The effect of TiO₂ with different morphologies on the electrical properties of the EPDM matrix has been comparatively analyzed and systematically investigated. The results show that the TiO₂ NFs/EPDM exhibit nonlinear conductivity at a lower content compared to TiO₂ NPs/EPDM composites. The threshold electric field of 18 wt.% TiO₂ NFs/EPDM is 10.8 kV/mm and the nonlinear coefficient is 2.77. With the content of TiO₂ NPs and TiO₂ NFs increases, the breakdown field strength of the composites gradually decreases. At the same content, the breakdown strength of TiO₂ NFs/EPDM is slightly lower than TiO₂ NPs/EPDM; the dielectric constant and dielectric loss of TiO₂ NFs/EPDM composites are slightly higher than that of TiO₂ NPs/EPDM composites. The simulation results show that the 18 wt.% TiO₂ NFs/EPDM can better homogenize the electric field, reduce the electric field at the end of the shielding tube, and improve the reliability of the safe operation of cable accessories. This work provides an effective method of preparing electric field graded materials.

TiO2; Different morphologies; EPDM Rubber; Electrical properties