The effects of ion irradiation on the dielectric properties of poly(ether ether ketone)

Temperature-dependent dielectric relaxation spectra of ion irradiated (11.2 MeV H+ and 25.6 MeV He2+) poly(ether ether ketone) (PEEK) were measured at frequencies between 50 and 10(5) Hz. The data were analysed by both Cole-Cole and Kohlrausch-Williams-Watts equations. beta(KWW) values were observed to decrease with irradiation, which was interpreted in terms of the Ngai et al. model as due to the increase of inter-chain coupling between the relaxing units caused by the additional constraints introduced by the cross linking. The effect of irradiation was also discussed in terms of local motion by studying the low temperature beta-relaxation in PEEK. Polar groups were attached to the phenyl rings by irradiation as evident from the progressive increase in the beta-relaxation peak intensity with dose.