Structure–property interplay in fully circular all-cellulose composites using structurally intact lignocellulosic fibers

• Water-regenerated cellulose showed higher crystallinity and thermal stability. • ACCs exhibited low porosity (<2 v/v%) with intact fiber–matrix interfaces. • Regenerated cellulose that was dissolved in EmimAc had higher tensile strength. • Bamboo fiber reinforced ACCs exhibited over 3-fold higher tensile strength than coir fiber reinforced ones. • Ionic liquids were efficiently recovered without property degradation. In this study, an innovative approach inspired by the all-cellulose composites (ACCs) concept was explored using regenerated cellulose as the matrix, reinforced with lignocellulosic fibers. Pulp cellulose was dissolved in two ionic liquids (ILs), EmimAc and BmimCI, and regenerated with two antisolvents, water and methanol, to form a cellulose matrix, while coir (CF) and bamboo (BF) fibers were employed as reinforcements. The relationship between these parameters on ACC s structure was comparatively investigated. The cellulose matrix regenerated by water exhibited higher crystallinity and thermal stability than the methanol-regenerated ones. The cellulose matrix dissolved in EmimAc enhanced the ACC’s tensile strength by up to 30 % to that of cellulose dissolved in BmimCI. The BF reinforcement translated to higher flexural strength and modulus, up to 45 % and 2-fold, respectively, than the CF ones. SEM and Micro-CT analyses revealed that the fibers were kept intact within the cellulose matrix, while ACCs had less than 2 v/v% porosity. The ILs employed to fabricate ACCs recovered from the antisolvent mixture showed no significant change in their properties. This approach bridges the gap between traditional ACCs and natural fiber-reinforced polymers, potentially opening new avenues for developing eco-friendly composites that leverage the inherent properties of lignocellulosic fibers.