Miscanthus × giganteus stalks as a potential non-wood raw material for the pulp and paper industry. Influence of pulping and beating conditions on the fibre and paper properties

Abstract

This manuscript describes the relationship between the method of processing (soda and kraft pulping) of Miscanthus × giganteus stalks into unbleached pulps of different residual lignin content (1.5–8.7 wt. %) and their beatability and properties. It was found that Miscanthus soda pulps with low residual lignin content need to be beaten for longer to achieve the same level of SR-freeness compared with kraft pulps. In order to obtain higher values of mechanical properties of handsheets prepared from soda and kraft Miscanthus pulps they have to be beaten to SR-freeness higher than 35 °SR. The mechanical properties of Miscanthus kraft pulps determined in static conditions (e.g. tensile strength) are better than those of soda pulps. A decrease in the kappa number of Miscanthus soda pulps below 20, lowers these properties distinctly. The tear index of Miscanthus pulps is good, while Gurley air-resistance is comparable with birch kraft pulp. Soda Miscanthus pulps having a higher content of residual lignin and kraft Miscanthus pulps of low and high residual lignin contents, due to the similarity of their properties with unbleached hardwood kraft pulps (birch, poplar, hornbeam), could probably replace the latter pulps in the production of packaging papers (e.g. sack paper).