In comparison with cellulose nanofibrils (CNF) from bleached kraft pulps, higher yield and lower production costs have recently increased the interest towards lignocellulosic nanofibrils (LCNF) promoting a large-scale industrial production. Evidently, the presence of both lignin and hemicelluloses facilitate fibrillation, decreasing the energy consumption while affecting the characteristics of the resulting LCNF. Lignin and the amount of anionic groups (e.g. carboxylic and sulphonic acid groups) in pulps can adjust the hydrophilicity of LCNF and contribute to the dispersion of the resulting fibrils. The modified cooking concept of neutral sulphite semi-chemical pulping (NSSC) process, currently under development, may offer a new type of raw material for the manufacture of LCNF. It is reasonable to expect that the neutral sulphite pulps, rich in lignin and hemicelluloses, and therefore high in yield, should consume less energy when fibrillated to LCNF. Additionally, supplementary information of the effect of galactoglucomannan and lignin for fibrillation is still needed. The pulps for fibrillation experiments originate from the sodium sulphite pulping of Scots pine chips under the initial pH of 7 or ~10 at 170°C and 180°C. The cooking liquor composes of Na<sub>2</sub>SO<sub>3</sub> (70 g/l) with or without anthraquinone (0-0.1% on o.d. wood). The produced pulps with the yield range of 55-85% are rich in galactoglucomannan and contain 9-24 wt-% of residual lignin. The electric charge of the pulps is increased by the introduction of sulphonic acid groups in residual lignin during pulping. The fibrillation of the pulps will be tested in a MKZA 10-15J Supermasscolloider friction grinder (Masuko Sangyo Co., Japan) by taking samples after 1-5 passes through the grinder representing varied degrees of fibrillation. Morphology, water retention value and rheology of the resulting LCNF gels will be investigated. Subsequently, the potential of selected LCNF gels in films may be tested.

Lignocellulosic nanofibrils from neutral sulphite pulps

251st National Meeting (2016)

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