Effect of drying method on the surface properties of cellulose nanofibril films

This study analyzes the effect of different drying methods on the surface properties of cellulose nanofibril (CNF) films obtained from bleached eucalyptus Kraft pulp. The surface quality of CNF films is crucial for enhancing their barrier properties, adhesion, and uniformity, particularly in multilayer or composite applications. Films were fabricated by casting, hot pressing, and double pressing under various conditions of pressure and temperature. Surface roughness, morphology, density, porosity, and contact angle were evaluated. The most effective method was double pressing in an oven at 110 °C and 1.8 kPa, achieving the lowest roughness (283.8 nm), highest density (1.34 g/cm³), low porosity (16.1%), and a contact angle of 63.1°, indicating a more compact and less hydrophilic surface. This study establishes a rapid and efficient method to produce CNF films with optimized surface properties, which are highly relevant for industrial applications in sustainable packaging, coatings, and barrier materials, where surface quality directly impacts functionality and competitiveness.