Effect of Dissolution Time on the Development of All-Cellulose Composites Using the NaOH/Urea Solvent System

DELGADO, JUAN FRANCISCO; SALVAY, ANDRÉS GERARDO; ARROYO, SILVANA; BERNAL, CELINA RAQUEL; FORESTI, MARÍA LAURA

Polysaccharides

MDPI

Lugar: Basilea; Año: 2023 vol. 4 p. 65 - 77

Innovativeand sustainable all-cellulose composites (ACCs) can be obtained by partialdissolution of cellulosic fibers and regeneration of the dissolved fraction.Among cellulose solvents, sodium hydroxide/urea solutions are recognized aspromising low-environmental impact systems. In this work, filter paper (FP) wasdissolved with a 7 wt% NaOH/12 wt% urea aqueous solution, kept at −18 °C fordifferent time intervals, regenerated with distilled water and finally driedunder different conditions. The developed films were characterized in terms ofmorphology, porosity, optical properties, crystalline structure, hydration andmechanical properties. The porosity of the composites decreased withdissolution time due to the progressive filling of voids as the cellulosicfibers’ surface skin layer was dissolved and regenerated. Samples treated for 4h showed the minimum values of porosity and opacity, high hydration and asubstantial change from cellulose I to cellulose II. Hot pressingduring drying led to relevant improvements in ACCs stiffness and strengthvalues.