It is known from previous research that the suspension of nanofibrillated cellulose is easily transformed into stable hydrogel with the process of mercerization. The goal of this work was the preparation of hydrogels from cellulose nanofibrils with basic alkaline processing, and a study of the effect that the concentration of the NaOH has on their formation. With differing concentrations of the alkaline solution the optimal correlation between the suspension of NFC, NaOH and H2O for the formation of a durable hydrogel was determined. To attain a hydrogel with antibiotic properties the chestnut tannin was added, as it is known that these tannins inhibit the growth of bacteria efficiently. From the stable and compact composite hydrogels thus produced we measured and calculated the mass, volume, density, water content, porosity and the content of the dry matter of the hydrogel. The hydrogels with optimal properties and durability were those with the mass ratio of NaOH and distilled water 20/60, 30/50. The antibacterial activity of tannin was visible as soon as 1% of tannin was added to a joint mass of hydrogel (100g). With increasing the concentration of tannin above 3% in reference to the mass of the NFC suspension, we negatively affected the compactness of hydrogels. Therefore, we concluded that adding tannins in a concentration above 3% is irrational, since it reduces the compactness of hydrogels, the antibacterial properties remain unchanged and the excess of tannin is flushed away.
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