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The utility properties of paper are dependent on the modification of the structure of the cellulose fibers, which is achieved via refining. The most important outcomes of the refining process are changes in the internal fibrillation and the shortening of the cellulose fibers. There are numerous opinions published in literature describing the relationship of these parameters and their impact on the final paper properties. These publications have been primarily based on the results of measurements conducted using insufficiently precise methods and simple speculations. The authors of this work decided to determine the effect of the refining intensity on the progress of internal fibrillation and shortening of cellulose fibers and the interrelation between these effects. Refining was performed with a laboratory Hollander beater, which was able to apply different refining loads. Utilizing additional control equipment, the specific edge load was also calculated. Finally, the impact of the refining effects (fibrillation and shortening) on the final properties of the paper were investigated.

The objective of this work was to investigate the influence of hydrogen bonds between fibres on static and dynamic strength properties of paper. A commercial bleached pinewood kraft pulp was soaked in water, refined in a PFI, and used to form paper webs in different solvents, such as water, methanol, ethanol, n-propanol and n-butanol, to determine the effect of their dipole moment on static and dynamic strength properties of resulting paper sheets. Paper which was formed in water, being the solvent of the highest dipole moment among the tested ones, showed the highest breaking length and tear resistance. When paper webs were formed in n-butanol, which was the least polar among the solvents, these parameters were reduced by around 75%. These results provide evidence of the importance of water in paper web formation and strong impact of hydrogen bonds between fibres on strength properties of paper.