Dielectric measurement and testing provide a method for determining the permittivity and loss factors as a function of temperature, frequency, time, or a combination of these variables. Plots of the dielectric properties against these variables yield important information and characteristics about the specimen under test.

This procedure can be used to do the following:

5.2.1 Locate transition temperatures of polymers and other organic materials, that is, changes in molecular motion (or atomic motion in the case of ions) of the material. In temperature regions where significant changes occur, permittivity increases with increasing temperature (at a given frequency) or with decreasing frequency (at constant temperature). A maximum is observed for the loss factor in cases where dipole motions dominate over ionic movement.³

5.2.2 Track the reaction in polymerization and curing reactions. This may be done under either isothermal or nonisothermal conditions. Increasing molecular weight or degree of crosslinking normally leads to decreases in conductivity.⁴

5.2.3 Determine diffusion coefficients of polar gases or liquids into polymer films on dielectric sensors. The observed change in permittivity typically is linear with diffusant concentration, as long as the total concentration is relatively low.⁵

This procedure can be used, for example, to evaluate by comparison to known reference materials:

5.3.1 The mix ratio of two different organic materials. This may be determined either through use of permittivity or loss factor values. In early studies, permittivity has been found to be linear with concentration.⁶

5.3.2 The degree of phase separation in multicomponent systems.

5.3.3 The filler type, amount, pretreatment, and dispersion.

This test method can be used for observing annealing and the submelting point crystallization process.

This test method can be used for quality control, specification acceptance, and process control.