Upcycling seaweed wastes into high-performance PBS nanocomposites for sustainable packaging applications

This study investigated the synthesis of cellulose nanofibrils (CNFs) from Caulerpa lentillifera, also known as green caviar or sea grapes, and used as a reinforcing agent in poly(butylene succinate) (PBS) composite films. Inadequate quality sea grapes, generally discarded in aquaculture, were chemical treated using alkaline and bleaching processes, followed by mechanical defibrillation. The synthesized CNFs with fiber diameters between 3.50 and 4.97 nm were produced. Characterizations of structural, thermal, and morphological properties confirmed the successful removal of lignin and hemicellulose, creating the production of high-purity CNFs. The as-synthesized CNFs were added into PBS as reinforcement at different concentrations (0.1-0.5 wt%) and their effects on the properties of the composite were evaluated. FTIR analysis indicated significant interfacial interactions between PBS and nanocellulose, while the presence of hydroxyl groups in CNFs led to a slight decrease in thermal stability. The DSC analysis showed minimal alterations in crystallization behavior. Increasing nanocellulose content reduced optical transparency due to light scattering. The effect arose from nanoscale fiber dispersion within the PBS matrix. The films remained semi-transparent and suitable for packaging requiring controlled light transmission. The research results verified that upcycling of seaweed waste into CNFs reinforced PBS high-performance biocomposites provided an environmentally sustainable material for packaging applications.