1. ABOUT THE DATASET -------------------- Title: Effect of Water on the Dissolution of Flax Fibers in the Ionic Liquid 1-ethyl-3-methylimidazolium acetate Creator(s): Fatimah A Albarakati [2], Michael E Ries [1], Peter J Hine [1] Organisation(s): 1: School of Physics and Astronomy University of Leeds. 2:Department of Basic Science, University College in Adam, Umm Al-Qura University, Makkah, Saudi Arabia Rights-holder(s):Unless otherwise stated, Copyright 2023 University of Leeds Publication Year: 2023 Description: This work has investigated the dissolution rate of flax fibers in the ionic liquid 1-ethyl-3-methylimidazolium acetate [C2mim] [OAc] with the addition of an anti-solvent, water. Optical microscopy has been used to analyses the resultant partially dissolved fibers. Distilled water was added to the solvent bath at the concentration of 1%, 2% and 4% by weight of the [C2mim] [OAc]. The effect of the addition of even small amounts of water was found to significantly decrease the speed of dissolution, decreasing exponentially as a function of water concentration. The resulting data of both pure (as received from the manufacturers) IL and IL/water mixtures showed the growth of the coagulated fraction as a function of both dissolution time and temperature followed time temperature superposition (TTS), and from this the dissolution was found to follow an Arrhenius behavior with an activation energy of 64 ± 5 kJ/mol for the IL as received (0.2%water). For 1%, 2% and 4% water systems, the activation energies were found to be 74 ± 7 kJ/mol, 97 ± 3 kJ/mol and 116 ± 0.6 kJ/mol respectively. Extrapolating these results to zero water concentration gave a value for the hypothetical dry IL (no water) of 58 ± 4 kJ/mol. Cite as: Fatimah A Albarakati, Michael E Ries, Peter J Hine (2023): Effect of Water on the Dissolution of Flax Fibers in the Ionic Liquid 1-ethyl-3-methylimidazolium acetate. University of Leeds. [Dataset] https://doi.org/10.5518/1278 Related publication: Albarakati, F.A., Hine, P.J. & Ries, M.E. Effect of water on the dissolution of flax fiber bundles in the ionic liquid 1-ethyl-3-methylimidazolium acetate. Cellulose (2023). https://doi.org/10.1007/s10570-023-05394-3 Contact: m.e.ries@leeds.ac.uk 2. TERMS OF USE --------------- Copyright 2023 University of Leeds. Unless otherwise stated, this dataset is licensed under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/. 3. PROJECT AND FUNDING INFORMATION ---------------------------------- Title: Fatimah A Albarakati PhD Project Dates: October 2020 - September 2024 Funding organisation: Saudi Arabia 4. CONTENTS ----------- File listing dataset.xlsx 5. METHODS ---------- 2.1. Materials Flax fibers were obtained from Airedale Yarns, Keighley, UK. Flax fibers were chosen to be the cellulose source which is formed from a continuous yarn fiber with a diameter of 0.5 mm. The solvent used was 1-ethyl-3-methyl-imidazolium acetate [C2mim] [OAc] with a purity ≥ 98% which was purchased from Proionic GmbH, Grambach, Austria. Epoxy (Epoxicure, Cold Cure Mounting Resin from Buehler, UK) was used to embed samples to examine and measure the fraction of dissolved fibers at each set of processing conditions. 2.2. Preparation sample Single flax fiber threads were wound separately around a polytetrafluoroethylene (PTFE) Teflon picture frame of dimensions 5 cm × 5 cm, fixing both ends of each single fiber (Fig.1a). Four separate fiber samples were wound onto each frame for testing, to give repeat measurements at the various chosen times and temperatures during processing (Fig.1b). The IL [C2mim] [OAc] was used and first pre-heated in a PTFE tray for 1 hour to stabilise at the chosen target temperature before the dissolution experiments were commenced. Then, the frames were submerged into the Teflon dishes which were filled with the IL [C2mim] [OAc] (Fig.1c), and then quickly returned to the vacuum oven (Fig.1d). Shellab 17L Digital Vacuum Oven SQ-15VAC-16, Sheldon Manufacturing, Inc., USA, was used to dissolve the flax samples at various temperatures and times (Fig.1e). After the dissolving process, the flax fiber samples were removed from the IL [C2mim] [OAc] and then immediately soaked in a water bath for 24 hours at room temperature to coagulate the dissolved cellulose, as shown in (Fig.1f), and the used IL [C2mim] [OAc] was collected for recycling. A drying process was employed after removing the fibers from the water bath, leaving to dry for more than 24 hours at room temperature before cutting the samples from the frame (Fig.1g). Fig.1: The process of dissolving flax single fibers in [C2mim][Ac]. 2.3. Characterization and qualification 2.3.1 Optical Microscopy Optical microscopy (BH2-Olymous Corporation, Japan) was used in conjunction with a CCD (Charge-coupled- device) camera to analyse the cross- sectional images of the microstructures of both the single flax fibres (raw fibres) and the partially dissolved (composite fibres). Epoxy resin was used to encapsulate the fiber samples for optical microscopy. Each sample was embedded in an epoxy resin, which was then ground down and polished to the fiber surface before examining in reflection to allow for clear images, as shown in Fig.2. To measure the ratio between the raw fibers (undissolved fiber, inner area) and the coagulated fraction (dissolved fiber, outer area). ImageJ processing software was used, as shown in Fig.3. The coagulated fraction CF was calculated using, CF=A_C/A_T (1) where A_C is the area of the cross-sectional of the coagulated cellulose and A_T is the total area of cross- sectional for coagulated cellulose plus raw cellulose. Fig.2: The epoxy resin embedding method. a) single flax fibers were embedded in an epoxy resin, b) fiber threads before grounding down and polishing, (c) fibers after fully curing to allow a clear images. Fig.3: A partially dissolved fiber shows the raw cellulose (inner core), the coagulated cellulose area and the total area of both raw and coagulated fiber (outer layer). 2.3.2 Antisolvent distilled water The antisolvent (distilled water) was mixed into the IL with a magnetic stirrer for 10 minutes prior to use. Three water concentrations were used: 1%, 2% and 4% by weight. Karl Fisher Titration (KFT) was used before and after the dissolution process to determine the amount of water content of the IL. KFT on the IL as received from the manufactures Proionic, showed this to contain 0.2% water. By adding 0.8% water to the original 0.2% water to make 1%, 1.8% water added to make 2% water, and 3.8% water added to make 4% water. The IL/water mixture exhibits a much higher vapor pressure and may thus evaporate under vacuum. Thus, the vacuum oven atmosphere was replaced with a nitrogen atmosphere to avoid evaporation while dissolving in the Leybold Sogevac vacuum oven. Several researchers have studied the interaction between [C2mim] [OAc] and water and found that their properties could be significantly changed in the presence of water; for example, the melting point, polarity, viscosity and surface tension of ILs are changed (Duchemin, Staiger, & Newman, 2014; Jacquemin, Husson, Padua, & Majer, 2006; Reid, Gammons, Slattery, Walker, & Shimizu, 2017; Zhou, Jiang, Wang, & Liu, 2020).