**3.2 Cellulose used in paper production**

In the refining process, for example for the production of paper, cellulose fibers are immersed in water. The fibrils, which make up the cells, are composed of crystalline regions that, when immersed in water, absorb a quantity of this water across all exposed crystalline surfaces, causing their swelling and decreased attraction between the fibrils. The mechanical action of shearing the fibers through refiners speeds up this swelling, as it exposes the surfaces previously located inside the fibers, causing an increase in surface exposure, which promotes a greater number of contacts and connections between the fibers, resulting in this stronger paper [1].

The steps of converting cellulose to paper involve many surface chemical interactions, interactions between fibers and colloidal particles. Understanding these interactions is useful for product development and improving the resolution of operational problems.
