Structural development in ion‐irradiated poly(ether ether ketone) as studied by dielectric relaxation spectroscopy

Abstract

Structural alterations to amorphous poly(ether ether ketone) (PEEK) produced by ion irradiation (11.2 MeV H 1 and 25.6 MeV He 21 ions) were investigated by dielectric relaxation spectroscopy. The analysis in terms of the Havriliak-Negami (HN) equation and the scaling model showed an increase in the intermolecular correlation with increasing irradiation dose. The dynamic fragility index (m) was estimated from Vogel-Fulcher-Tammann analysis. Ion irradiation not only elevated the glass-transition temperature (T g ) but interestingly decreased m of the PEEK chains around T g . This was due to increasing polar interaction and better packing efficiency of the irradiated samples compared with those of amorphous PEEK. The average size of the cooperative rearranging region decreased in line with decreasing m and indicated an increase in the rigid amorphous phase fraction after irradiation. The analysis of the direct-current conductivity confirmed that there was a strong coupling between the macroscopic ion transport and concerted segmental motion.

Two-dimensional FTIR spectroscopic analysis of crystallization in cross-linked poly(ether ether ketone)

“…It has been reported that amorphous PEEK contains an intermediate phase called rigid phase [28]. It seems likely that this rigid phase was enhanced by the introduction of cross-linking which improves the backing efficiency of the chains [6]. The shifts observed in the most FTIR band in the cross-linked PEEK support the later conclusion.…”

“…Irradiations have been utilized as mean to introduce cross-linking in the structure of PEEK [4][5][6] to improve its dimensional stability after chemical modification by sulfonation. The aim is being to produce materials with desirable combination of swelling and conductivity characteristics suitable for fuel cell application [3,7].…”

Electronic irradiation ageing in the vicinity of glass transition temperature for PEEK space applications

“…For the α relaxation, as predicted by the VTF theory, the value of T ∞ ≃ T g -50°C confirms its attribution to the dielectric manifestation of the glass transition. The fragility index values reported in the literature lie between 150 and 280, depending on the analysis method and on the material state [41,42]. In this study, a value of 127 was calculated for pristine PEEK which is in the same order of magnitude as literature values.…”

The crosslinking of poly (ether ether ketone): Thermally and by irradiation

“…Another interest of the present work was the investigation of the efficiency of proton irradiation conditions to optimize polymer modifications and reduce the cost of the final product. In our previous works, irradiations with ions as a route for preparing crosslinked PEEK have been discussed and the materials properties of the resultant materials have been investigated in details . Comparing with helium irradiation, proton irradiation has the advantage of enabling more PEEK layers to be irradiated with different absorbed dose at the same time.…”