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

Abstract

Temperature-dependent dielectric relaxation spectra of ion irradiated (11.2 MeV H ? and 25.6 MeV He 2? ) poly(ether ether ketone) (PEEK) were measured at frequencies between 50 and 10 5 Hz. The data were analysed by both ColeCole and Kohlrausch-Williams-Watts equations. b 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 b-relaxation in PEEK. Polar groups were attached to the phenyl rings by irradiation as evident from the progressive increase in the b-relaxation peak intensity with dose.

Molecular dynamics in ion‐irradiated poly(ether ether ketone) investigated by two‐dimensional correlation dielectric relaxation spectroscopy

“…Irradiation had a profound effect on the dielectric response of PEEK. As reported earlier from dielectric and thermal studies, changes in the intensity of the β relaxation of PEEK were mainly related with oxidation. Increasing irradiation dose resulted also in shifting the α relaxation peak to higher temperatures reduced the extent of crystallization of the amorphous polymer, and at a sufficiently high dose, crystallization is completely inhibited .…”

“…Increasing irradiation dose resulted also in shifting the α relaxation peak to higher temperatures reduced the extent of crystallization of the amorphous polymer, and at a sufficiently high dose, crystallization is completely inhibited . Although the general irradiation effects are similar for both ion (proton and helium ions), there were some indications that the dielectric properties of polymers are influenced by the so‐called linear energy transfer (LET) effect of the irradiated ion used …”

“…Irradiation with ions was carried out using the University of Birmingham's Scanditronix MC40 Cyclotron operating at 12.5 MeV for protons (H + ) and 33 MeV for helium ions (He 2+ ). The full irradiation setups were discussed in previous works …”

“…This indicates that the ions used on irradiation affect the dielectric properties of PEEK to different extent and that He 2+ ions have more effects on the processes investigated. This is in agreement with the ion LET effect and consistent with the analysis of 1D dielectric study reported elsewhere …”

“…A literature survey reveals that the dielectric properties of amorphous and irradiated PEEK have been studied using classical methods and mathematical formula . The objective of this work, however, was to use recent developments namely two‐dimensional correlation spectroscopy (2D COS), to gain further information in understanding the complex relaxation mechanism that characterizes the ion‐irradiated polymers.…”