Effect of electrospinning and carbonization on dielectric and charge transport properties of PAN–TiO 2 –CNT composite nanofibers

This study examines how processing methods influence the dielectric relaxation and charge transport behavior of composite nanofibrous materials. Composite films were fabricated using solution casting and electrospinning, followed by controlled carbonization under identical filler loading conditions to systematically evaluate the effect of structural evolution on electrical performance. Electrospinning generated a well-defined interconnected nanofibrous architecture with a high interfacial area, which significantly enhanced interfacial polarization. As a result, the electrospun samples exhibited high low-frequency dielectric permittivity (ε′ ≈ 10 3 –10 4 at 1 in the low-frequency regime (0.1–100 Hz)) and pronounced non-Debye relaxation behavior. Subsequent carbonization transformed the polymer matrix into a distorted carbonaceous framework, promoting the formation of an efficient conductive network. This structural transition shifted the dominant mechanism from polarization-governed relaxation to transport-controlled conduction, leading to an electrical conductivity of approximately 9.5 S m −1 . Electric modulus analysis and impedance-based equivalent circuit modeling revealed a progressive reduction in bulk resistance from 10 7 Ω for cast films to 10 2 –10 3 Ω after carbonization. Weibull statistical analysis further indicated improved dielectric reliability, with characteristic breakdown strengths reaching 180 MV m −1 . The results demonstrate that electrospinning combined with post-carbonization offers an effective processing strategy for tailoring dielectric relaxation and charge transport properties in composite nanofibrous systems, making them promising candidates for advanced functional applications.