Dissolution of cotton by 1-ethyl-3-methylimidazolium acetate studied with time–temperature superposition for three different fibre arrangements

This study has investigated the dissolution of cotton fibres in the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) for three fibre arrangements. Dissolution was carried out with excess [C2mim][OAc] at various temperatures and times followed by coagulation with water. Optical microscopy (OM) of the resulting processed and dried cotton fibres indicated that this procedure produced a coagulated fraction surrounding the original fibres. X-ray diffraction (XRD) showed that the crystal structure of this coagulated fraction was predominantly cellulose II, as opposed to the original fibres—mostly cellulose I. The OM and XRD results showed that growth of the coagulated fraction obeyed time–temperature superposition (TTS) and displayed an Arrhenius behaviour allowing a dissolution activation energy to be determined. Although the growth of the coagulated fraction with time were different for these distinct three arrangements, all could be individually shifted to form master curves using TTS, leading to very similar activation energies, 96 ± 3 kJ/mol (23 ± 1 kcal/mol).