Fibre spinning from various low refined, recycled lignocelluloses using ionic liquid

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School of Chemical Technology | Doctoral thesis (article-based) | Defence date: 2018-10-05
Degree programme
108 + app. 92
Aalto University publication series DOCTORAL DISSERTATIONS, 171/2018
This dissertation presents the application of Ioncell technology to the production of man-made cellulosic fibres using recycled and low refined lignocellulosic materials. Ioncell technology consists of a dry-jet wet spinning process using ionic liquid (IL) as a polymer solvent. High performance regenerated cellulosic fibres have been produced with ionic liquid [DBNH]OAc (1,5-diazabi-cyclo[4.3.0]non-5-enium acetate)/dissolving grade pulp dopes. It is also found that [DBNH]OAc is a powerful solvent for low refined lignocelluloses. The effect of lignin and hemicellulose on the fibre spinning is studied using cellulose and lignin (isolated pure lignin) blends and unbleached kraft pulps (residue lignin in native form). Composite fibres can be produced with lignin content in blends up to 50 wt%. Fibres produced from cellulose and lignin blends reveal a decrease in the crystallinity and degree of orientation, while the lignin share increases. As a result, the tensile strength of the composite fibres drops. On the other hand, increases in lignin content enhance the hydrophobicity and the carbonisation yield at high temperature. The unbleached pulps with different lignin content are yielded by kraft pulping with varying intensity. Prior to dissolution in IL, the degree of polymerisation of the pulp is adjusted by using acid-catalysed hydrolysis and electron beam irradiation for producing dopes with optimal viscosity. Fibres could be spun even from only mild refined pulps. The fibre properties display a similar trend compared to composite fibre as lignin content in pulps raises. Unlike the fibre produced from pure lignin, fibres containing native lignin exhibit improved moisture accessibility due to the morphological changes of the fibres. This thesis also investigates the utilisation of waste fine paper, cardboard, and newsprints as raw materials. All these raw materials are refined gradually to examine the effect of the substrates' chemical composition on the spinnability. Except for untreated cardboard, newsprint, and low refined kraft newsprint, all substrates demonstrate high spinnability leading to fibres with high tensile properties. An environmentally friendly alkaline glycerol pulping process is found to be an optimal pre-treatment for newsprint. Ioncell is a promising process for the conversion of recycled and low refined lignocellulose into high-value textile products. Prototype fabrics are knitted with yarns that are produced from fibres spun from cellulose and lignin blends, recycled cardboard, and newsprint. The lignin contained in the fibre can be used as a natural dye. The shade of fibres depends on the lignin content exhibits, from beige to dark brown.
Supervising professor
Sixta, Herbert, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland
Thesis advisor
Hummel, Michael, Dr., Aalto University, Department of Bioproducts and Biosystems, Finland
cellulose, hemicellulose, lignin, ionic liquid, dry-jet wet spinning, recycled material, low refined pulps
  • [Publication 1]: Ma, Yibo; Asaadi, Shirin; Johanson, Leena-Sisko; Ahvenainen, Patrik; Reza, Mehedi; Alekhina, Marina; Rautkari, Lauri; Michud, Anne; Hauru, Lauri; Hummel, Michael; Sixta, Herbert. High-StrengthComposite Fibres from Cellulose-Lignin Blends Regenerated from Ionic Liquid Solution. ChemSusChem, 2015, vol 8, issue 23, pp 4030-4039.
    DOI: 10.1002/cssc.201501094 View at publisher
  • [Publication 2]: Ma, Yibo; Hummel, Michael; Määttänen, Marjo; Särkilahti, Airi; Harlin, Ali; Sixta, Herbert. Upcycling of waste paper and cardboard to textiles. Green Chemistry, 2016, vol 18, pp 858-866.
    DOI: 10.1039/C5GC01679G View at publisher
  • [Publication 3]: Ma, Yibo; Stubb, Jonas; Kontro, Inkeri; Nieminen, Kaarlo; Hummel, Michael; Sixta, Herbert. Filament spinning of unbleached birch kraft pulps: Effect of pulping intensity on the processability and the fibreproperties. Carbohydrate Polymers, 2018, Vol 179, pp 145-151.
    DOI: 10.1016/j.carbpol.2017.09.079 View at publisher
  • [Publication 4]: Ma, Yibo; Kontro, Inkeri; Hummel, Michael; Sixta, Herbert. High performance man-made cellulosic fibres from recycled newsprint. Green Chemistry, 2018, Vol 20, pp 160-169.
    DOI: 10.1039/C7GC02896B View at publisher