Fibre deformations in bagasse pulp induced by high consistency refining and their effect on strength properties of paper

Fibre deformations have a significant influence on fibre strength and paper properties. There are plenty of researches on the deformations of wood pulp fibres. However, the effect of fibre deformations on fibre and sheet properties of non-wood pulps has not been investigated extensively. The present study focuses on the fibre deformations in bagasse pulp induced by high consistency (HC) refining and their effect on the strength properties of paper. The refining behaviour of bagasse pulp fibres as a function of refining plate gap is compared with that of pine pulp fibres. In addition, the stability of the fibre deformations is investigated through subsequent PFI mill beating. The results show that for these two different kinds of pulps, HC refining induces fibre deformations (curl and kinks) in a different way. Fibre curl and kinks of bagasse fibres both increased steadily with HC refining. Subsequent PFI mill beating made the bagasse fibres even more deformed. However, for pine fibres, most of the fibre deformations (curl and kinks) induced by HC refining are reversible and can be released by the PFI mill beating. HC refining contributed to the improvement of the strength properties of handsheets with exception of the elongation for bagasse pulp. Additionally, the results indicated that curly fibres contribute to increased sheet elongation for pine pulp but not for bagasse pulp.