Critical Evaluation of the Methods for the Characterisation of the Degree of Sulfonation for Electron Beam Irradiated and Non-Irradiated Sulfonated Poly(ether ether ketone) Membranes

• DOI: 10.20944/preprints202308.0792.v1
• Publication Date: 2023-08-11T00:43:14Z
• Authors: Laura Dace Pakaln...; Elizabete Maskova; Rudolfs Janis Zab...; Liga Avotina; Einars Sprugis; Ingars Reinholds; Magdalena Rzepna; Guntars Vaivars; Elina Pajuste
• Keywords: degree of sulfonation; Research Subject Categories::NATURAL SCIENCES; :NATURAL SCIENCES [Research Subject Categories]; sulfonated poly(ether ether ketone); Article; electron beam irradiation

The aim of this study is to compare different methods used for determination of the DS for sulfonated membranes before and after high dose irradiation. Commercial PEEK was homogenously sulfonated up to DS of 60-90% and the membranes were prepared using solvent casting method. Part of the samples were irradiated with 10 MeV electron beam up to 500 kGy dose to assess the ionising radiation induced effects. Both non-irradiated and irradiated membranes were characterized by Fourier Transformation infrared (FT-IR) spectrometry, thermogravimetric analysis (TGA), proton nuclear magnetic resonance (1H-NMR), electrochemical impedance analysis and for the first time for non-irradiated membranes by spectrophotometric analysis with Cr(III). Comparison of the above-mentioned methods for application for DS assessment was done. It was observed that irradiated membranes presented a higher value of DS. Appearance of different new signals in 1H-NMR and FT-IR spectra of irradiated membranes indicated the effects of radiation induced changes in the structure of SPEEK materials. It was determined that the novel method with Cr(III) is applicable for the determination of SPEEK DS under 80%.