Microfibrillated cellulose-reinforced bio-based epoxy composites for liquid deposition modeling

Abstract Sustainable alternatives to fossil-derived resins for additive manufacturing are increasingly in demand. This study investigates the use of microfibrillated cellulose (MFC) as a renewable reinforcing and rheology-modifying component in bio-based epoxy systems for Liquid Deposition Modelling (LDM) 3D printing. Composite pastes were formulated combining a cardanol-based epoxy novolac resin with varying amounts of aqueous MFC suspensions. A novel methodology using a latent hardener enabled the removal of water introduced with MFC prior to printing and curing, minimizing shrinkage and void formation. Increasing MFC content resulted in higher insoluble fraction and enhanced thermomechanical properties, with the tensile modulus increasing up to sevenfold. Effective filler dispersion at MFC loadings below 10 wt% was confirmed by scanning electron microscopy, complemented by fitting of the experimental Young’s moduli using the Halpin–Tsai model. To assess printability, the rheological behavior of the uncured composite pastes was evaluated. A formulation containing 7 wt% MFC was successfully printed by LDM upon addition of a small amount of bisphenol A diglycidyl ether as reactive diluent. These findings highlight the potential of MFC as a multifunctional additive for LDM processing of sustainable epoxy composites.