A dielectric study of poly-ether-ether-ketone (PEEK) and poly-ether-sulphone (PES) films

Many polymers such as Teflon and the polyolefines can be used to produce electrets which have a relatively stable external electrical field as a result of ordered molecular dipoles or the presence of stable charges. The dielectric behaviour of such materials under the influence of electrical fields is important for the formation of electrets. The relatively new aromatic polymers of poly(ether sulphone), PES, and poly(ether ether ketone), PEEK, are important engineering materials due to their good electrical and mechanical properties. However little data is available on their dielectric behaviour which is important in the evaluation of their potential use as materials for electrets. In this study dielectric behaviour of PES and PEEK was examined over a range of temperatures and electric field strengths by employing the techniques of isothermal transient current measurement (TC) and thermally stimulated discharging current measurement (TSDC). Differential scanning calorimetry (DSC) was also undertaken to establish any correlation between structural changes and dielectric behaviour.