Prominent nonlinear electrical conduction characteristic in T-ZnOw/PTFE composites with low threshold field

摘要

Tetra-needle-shaped zinc oxide whisker/polytetrafluoroethylene (T-ZnOw/PTFE) composites with low threshold field were prepared via compression molding and sintering process. The addition of T-ZnOw endowed the T-ZnOw/PTFE composites a remarkable nonlinear conductivity characteristic under applied electric field. Dependence of threshold field on the concentration of T-ZnOw was observed. With increased T-ZnOw fillers loading, the threshold field of composites decreased while the conduction current density increased, which showed a nonlinear electrical conduction characteristic. The dielectric constant increases with the increasing of T-ZnOw loading. While the volume resistivity and breakdown strength of the composites decreased with increasing the loading of T-ZnOw. Compared with pure PTFE, T-ZnOw/PTFE composites with 30 wt% T-ZnOw loading also displayed a significant improved thermal conductivity and a low thermal expansion coefficient (TEC), which properties were important in practical application.