Electrical and thermal properties of PTFE-Sr2ZnSi2O7 composites

A new polymer-ceramic composite was prepared using PTFE and low loss Sr₂ZnSi₂O₇. The dielectric properties of the composite were studied in the microwave and radiofrequency ranges. The relative permittivity (ε_r) and dielectric loss (tan δ) increased with the filler loading from 0.10 to 0.50 volume fractions (v_f). The observed values of ε_r, thermal conductivity and coefficient of thermal expansion (CTE) were compared with the corresponding theoretical predictions. The ability of the composite towards moisture absorption resistance was studied as a function of filler loading. It was also found that the variation of ε_r was less than 2% in the temperature range 25–90 °C, at 1 MHz. For a filler content of 0.50 v_f, the PTFE/Sr₂ZnSi₂O₇ composite exhibited ε_r = 4.4_, tan δ = 0.003 (at 4–6 GHz), CTE = 38.3 ppm/°C, thermal conductivity = 2.1 W/mK and moisture absorption = 0.09 wt%.