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 (epsilon(r)) and dielectric loss (tan delta) increased with the filler loading from 0.10 to 0.50 volume fractions (v(f)). The observed values of epsilon(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 epsilon(r) was less than 2% in the temperature range 25-90 A degrees C, at 1 MHz. For a filler content of 0.50 v(f), the PTFE/Sr2ZnSi2O7 composite exhibited epsilon(r) = 4.4(,) tan delta = 0.003 (at 4-6 GHz), CTE = 38.3 ppm/A degrees C, thermal conductivity = 2.1 W/mK and moisture absorption = 0.09 wt%.