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.

Results of enzymatic hydrolysis of pine kraft cellulosic pulps (Kappa numbers ranging from 17.2 to 86.2) and waste fines from paper production line suggest that they are potential feedstocks for biofuel production. Glucose (61-68 % d.w.) and reducing sugars (around 90 % d.w.) yields from the pine cellulosic pulps with Kappa numbers ranging between 17.2 and 47.7 were higher than from the two pulps with Kappa numbers of 60.9 and 86.2. Glucose and reducing sugars yields from the latter pulps were around 54 and 45 % d.w. and 78 and 67 % d.w., respectively. The highest yields of glucose and total reducing sugars on a pine wood dry weight basis (29.3 and 43.1 %, respectively) were derived from the pulp with the Kappa number of 47.7. Thus the complete lignin removal from pine wood was not necessary to obtain maximum yields of glucose and other reducing sugars. Enzymatic hydrolysis of the fines from pine wood processing in a paper mill yielded around 75 % glucose and 78 % total reducing sugars on a dry weight basis that corresponded to around 34 and 36 % on a pine wood dry weight basis.

Typical bleached pinewood kraft pulp from a paper mill was immersed in either water or different alcohols, such as methanol, ethanol, n-propanol, and n-butanol, and then refined in a PFI mill. After refining, changes in the internal fibrillation of the fibres were evaluated by measurements of water retention values (WRV), while fibre shortening was determined by measurements of the average weighted fibre length. The objective of this study was to determine the influence of a liquid used for refining on the principal refining effects such as the internal fibrillation and fiber shortening. The highest increase in the internal fibrillation was observed for the pulp samples refined in water, which has the higher dipole moment than the alcohols. For these samples, WRV increased from 93% to 201%, while the average weighted fiber length was reduced by only 0.6 mm. When the pulp was beaten in n-butanol, which was the least polar liquid among the liquids investigated, liquid retention value increased by only 23.5%, while the average weighted fibre length was reduced by 1.37 mm. These results showed the importance of water in the beating of cellulose fibres and demonstrated that the outcomes of this process depended on the dipole moment of the fiber immersion liquid.

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.