A relaxation in the crystal structure of ceramic materials causes this value to "age" over time, and it increases greatly at the Curie point.
Cyclic olefin copolymer fibers are often used since they have a low value of this. A relaxation in the crystal structure of ceramic materials causes this value to "age" over time, and it increases greatly at the Curie point. The value for polar substances such as water is extremely high, while non-polar substances have a lower value.  It is measured by the ratio of capacitance with the tested material between the plates to the capacitance with a vacuum between the plates.  FTP name this ratio of a material to carry an alternating current compared to a vacuum.
Cyclic olefin copolymer fibers are often used since they have a low value of this.
{Dielectric} Constant