Performance of SLA Resins Containing Graphene Oxide and Fractionated Kraft Lignin

Additive manufacturing by stereolithography (SLA) is widely used for fabricating complex polymeric parts. However, photocurable resins typically exhibit brittle behavior. In this context, the incorporation of nanofillers has emerged as a strategy to tailor mechanical performance, although challenges related to dispersion and processability remain. This work investigates the co-incorporation of graphene oxide (GO) and kraft lignin, including a low-molecular-weight fraction (FKL), into acrylate-based photocurable resins processed by SLA. Pre-curing dispersion and viscosity were evaluated by optical microscopy and rotational rheometry. The mechanical, viscoelastic, and fracture behavior of the printed nanocomposites was assessed by tensile testing, dynamic mechanical analysis, and scanning electron microscopy. The results show that all formulations exhibited viscosities suitable for SLA processing. The presence of FKL promoted improved GO dispersion and more stable rheological behavior compared with unfractionated lignin. At low lignin contents, a pronounced synergistic effect with GO led to enhanced tensile strength, whereas increasing lignin content reduced stiffness and glass transition temperature while significantly increasing elongation at break, particularly for FKL-based systems. Overall, these findings demonstrate that lignin fractionation is an effective strategy to modulate dispersion, mechanical response, and toughness in GO-containing photocurable resins.