High-Yield Cellulose Nanocrystals from Bleached Eucalyptus Fibers via Maleic Acid Hydrothermal Treatment and High-Pressure Homogenization.

This study reports the preparation of cellulose nanocrystals (CNCs) from commercial bleached eucalyptus Kraft pulp (BEKP) using a hydrothermal treatment in the presence of maleic acid (MA), followed by high-pressure homogenization. Compared with conventional hydrolysis methods, this approach offers significant advantages, including lower acid concentration, higher yield, and milder processing conditions. CNCs were produced with a high yield (70-85 wt %) by high-pressure homogenization of hydrothermally treated BEKP fibers with 10-20 wt % maleic acid at 150 °C, giving rise to a stable translucent gel of CNCs with a rod-like morphology (200-400 nm length and 10-40 nm width). The reinforcing potential of the CNCs was also assessed by preparing nanocomposite films with CNC contents of up to 15 wt %, and the results were compared to commercial CNCs from CelluForce. Additionally, their biodegradability in aquatic media was assessed using biological oxygen demand, with results compared to those of neat cellulose fibers. The MA-assisted hydrothermal process is an environmentally friendly alternative to conventional CNC production methods, offering higher yields and enhanced thermal stability while preserving a strong reinforcing property.