Dielectric properties of Teflon from room temperature to 314°C and from frequencies of 102 to 105 c/s

Measurements of dielectric constant, dielectric loss and d.c. conductivity of Teflon were made from room temperature to temperatures just below the 327°C first order transition point and from frequencies of 10² to 10⁵ c/s on the high temperature sample holder described in the previous paper. Throughout this entire temperature and frequency range the dissipation factor never exceeds the smallest observable value, i.e., 2 ×10⁻⁴ and, consequently, there is no significant frequency dependence of the dielectric constant at any temperature. The d.c. conductivity is always less than its smallest observable value, i.e., 2 × 10⁻¹⁵ mho/cm, throughout this entire temperature range. The dielectric constant is computed to decrease from about 2.02 at 24°C to about 1.84 at 300°C. Its temperature dependence is in approximate agreement with values predicted from the experimental thermal expansion coefficient and the Clausius-Mosotti equation.