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

Abstract

This paper reports the first use of temperature–temperature 2D correlation dielectric relaxation spectroscopy (2D COS‐DRS) to study the molecular relaxation dynamics in ion‐irradiated poly(ether ether ketone) (PEEK). With the help of the high resolution and high sensitivity of 2D COS‐DRS, it was possible to locate the position of the motion of water molecules in the dielectric spectrum of PEEK. This occurred at −20°C and increased in intensity on increasing water contents. On irradiation, a new relaxation was observed at −75°C and −85°C for proton and helium ion‐irradiated samples, respectively. This increased in intensity on increasing radiation dose and was assigned to main‐chain phenyl motions of the cross‐linked units of the polymer. 2D COS‐DRS was also successfully applied to resolve the overlap in molecular events in the region of glass transition. Three processes that change in different directions with respect to ion irradiation dose were identified. These were at 160°C, 175°C, and 240°C and were assigned to the α relaxation, second α relaxation, and the onset of conductivity, respectively. In addition, hybrid 2D COS‐DRS was used to investigate the effect of the so‐called linear energy transfer effect, and the results showed that helium ions were more effective in cross‐linking PEEK. Copyright © 2013 John Wiley & Sons, Ltd.

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.…”

“…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. 3,6,[12][13][14][15][16][17] 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. In addition, proton irradiation has extensively larger linear energy transfer (LET) values compared with MeV electrons and c-rays.…”

Natural sunlight ageing of control and sterilized poly(ethylene terephthalate): Two‐dimensional infrared correlation spectroscopic investigation

“…The asynchronous correlation spectrum, on the other hand, locates variations in spectral intensities that are not synchronously correlated. The signs of cross‐peaks from both synchronous and asynchronous spectra yield information about the sequential order of the specific bands changes . The region 1800 to 600 cm −1 of the FTIR spectra, where most of changes occurred, of PET after ageing was discussed in the following paragraphs.…”

“…Two‐dimensional correlation spectroscopy, introduced by Noda, has been applied widely to analytical spectroscopies . Limitations encountered in 1D spectroscopy including the overlapped molecular events and weak signal to noise ratio (SNR), were resolved by the use of 2D‐COS which simplifies the complex spectra and improves spectral resolution through the spreading of peaks over a second dimension.…”

The sulfonation of poly(ether ether ketone) as investigated by two‐dimensional FTIR correlation spectroscopy

“…It has found applications in wide range of analytical spectroscopies. [16][17][18] Another merit of 2D-COS is that it can be used to determine the specific sequential order of spectral intensity changes. 15,17,19,20 The objective of this work is to investigate the capability of 2D-COS to obtain structural information related to the side reaction occurring on sulfonation of PEEK, the aromatic ring which is sulfonated and to determine an FTIR band which can be used for the quantitative determination of sulfonation degree.…”