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The insertion of oat husk lignin onto chemithermomechanical pulp (CTMP) fibers was studied to increase fiber hydrophobicity. The pretreated pulp samples were subsequently used for preparation of handsheets for characterization. Treatment of CTMP with laccase in the presence of oat husk lignin resulted in a significant increase in hydrophobicity of the handsheet surface, as indicated by dynamic contact angle analysis. Water absorption time of 8 s was obtained with initial contact angle of 118°. Although the handsheet's brightness was reduced by 33%, tensile index was only subtly decreased. Neither laccase nor oat husk lignin alone gave much improved water absorption times. Therefore, handsheets made of laccase-treated pulp with and without oat husk lignin were further examined by XPS, which suggested that both laccase and oat husk lignin were inserted onto CTMP fibers. The oat husk lignin was distributed as heterogeneous aggregates on the handsheet surface whereas laccase was uniformly distributed. Evidence was obtained that the adsorbed laccase layer formed a noncovalent base for the insertion of oat husk lignin onto fiber surfaces.

The use of nanomaterials and polymers from renewable resources is important in the search for sustainable alternatives to plastic-based packaging materials and films. In this work, self-supporting thin films prepared from derivatized and non-derivatized nanocellulose and cellulose derivatives were studied. The effect of drying temperature on the film-forming behavior of compositions comprising hydrophobically modified ethyl(hydroxyethyl)cellulose (EHEC), native microfibrillated cellulose (MFC) and nanocellulose made from methyl cellulose was determined. The interaction between the components was assessed from viscosity measurements made at different temperatures, the result being linked to a thermal-dependent association during liquid evaporation, and the subsequent barrier and film-forming properties. The effect of temperature on suspensions was clearly different between the materials, confirming that there were differences in interaction and association between EHEC–MFC and methyl nanocellulose–MFC compositions. The amphiphilic EHEC affected both the suspension homogeneity and the film properties. Air bubbles were formed under certain conditions and composition particularly in MFC films, dependent on the drying procedure. The presence of air bubbles did not affect the oxygen transmission rate or the oil and grease resistance. An increasing amount of MFC improved the oxygen barrier properties of the films.

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