The Trap and Dielectric Characteristics of Polyimide Nanofiber Membranes at Different Temperatures

Polyimide nanofiber membranes, as a high-performance insulation material, have garnered considerable attention and hold promising application prospects. In this study, polyimide nanofiber membranes were prepared by electrospinning process, and their surface potential decay, traps, and dielectric properties were investigated under temperature conditions of
$25 \ {}^{\circ} \mathrm{C}, 50 \ {}^{\circ} \mathrm{C}, 75 \ {}^{\circ} \mathrm{C}$
, and 90
${}^{\circ}{\mathbf{C}}$
utilizing an isothermal surface potential decay test system and a wideband dielectric spectroscopy test system. The results indicate that as the temperature rises, the traps energy levels escalate, the density of shallow traps diminishes, and the density of deep traps shows an overall increasing trend. Elevated temperature extends the average free path of electron motion, intensifying electron capture and emission. Furthermore, the rise in temperature induces thermal depolarization, leading to a reduction in the dielectric constant and dielectric loss of the polyimide nanofiber membranes. This study holds important theoretical value and engineering significance for advancing the application of polyimide nanofiber membranes.