Study On Preparation And Properties T-ZnOw Filled Polytetrafluoroethylene Composites

Polytetrafluoroethylene (PTFE) possesses good chemical stability, high temperature resistance, outstanding stability of dielectric properties versus frequency and temperature and excellent electrical insulating properties. As a result, the polymer (PTFE) can be widely applied in aviation and electric field. This work prepared tetra-needle-shaped zinc oxide whisker/polytetrafluoroethylene (T-ZnOw/PTFE) composites via cold compression and sintering processes. The PTFE was employed as matrix and T-ZnOw as fillers. The images, electrical and thermal properties of the composites were studied systematically. The main work can stated as follows,(1) The surface of T-ZnOw was modified by silane coupling agent (KH570). Except for dispersion of modified T-ZnOw fillers in PTFE matrix, FT-IR and XRD analysis of T-ZnOw/PTFE composites were also studied. The investigation showed that silane coupling agent (KH570) could improve the interface compatibility effectively of fillers and matrix.(2) With T-ZnOw filling in PTFE matrix, the image of T-ZnOw/PTFE composites and the influence of T-ZnOw content to electrical performance of the composites were studied. Results showed that dielectric constant of T-ZnOw/PTFE composites increased while volume resistivity, breakdown strength and the threshold field corresponding with electrical field-current density (E-J) curves decreased with increasing the loading of T-ZnOw. The E-J curves showed non-linear electrical conduction. Besides the mechanism of non-linear electrical conduction was explored elementarily.(3) The dependence of thermal properties of composites to T-ZnOw loading was also studied. The results showed that thermal conductivity of T-ZnOw/PTFE composites rose with increasing the loading of T-ZnOw. Moreover, when the mass content of T-ZnOw fillers reached to 30%, the thermal conductivity of T-ZnOw/PTFE composites improved two times compared with pure PTFE. In addition, thermal expansion coefficient (TEC) of composites decreased with increasing loading of T-ZnOw fillers.