Enhanced microfibrillated cellulose-based film by controlling the hemicellulose content and MFC rheology.

Understanding of how hemicellulose acts on the rheology of microfibrillated cellulose in suspension or after drying is insufficient. In this study, different concentrations of hemicellulose in the cellulose pulp of Eucalyptus sp. were obtained by alkaline treatment with potassium hydroxide. The treated pulps and the suspension of microfibrils obtained were characterized by thermogravimetric analysis, zeta potential, scanning electron microscopy, rheological analysis, X-ray diffraction and dynamic mechanical analysis. The lowest hemicellulose content obtained was approximately 2% wt. Treatments with KOH above 10% did not cause a significant reduction in hemicellulose content and caused a change in the type of cellulose crystallinity. The rheological analysis showed that the apparent viscosity of the suspensions was strongly influenced by the presence of hemicellulose. The morphology of the MFC films of the treated pulps presented the appearance of voids with the reduction of hemicellulose content, generating a decrease in its mechanical properties.