Abstract
The study investigated the addition of nanocellulose (NC) as a reinforcing agent in wood-phenol resorcinol formaldehyde (PRF) composites for thermoset extrusion-based manufacturing. Three types of NC (cellulose nanocrystals (CNC), bleached nanofibers (BNFs), and unbleached nanofibers (UBNFs)) at 1–3% loadings and new (NP) and 4-year old (OP) PRF resin were evaluated by a combination of thermal analysis, rheology and flexural testing. The NP was shown to gel at a lower temperature than OP. CNC addition advanced gelation and yield stress; whereas, UBNFs reduced viscosity and yield stress through plasticization but were suitable for extrusion. The NC-reinforced wood–PRF formulations were successfully extruded into continuous composite rods. A flexural modulus of 8.1 GPa and strength of 77 MPa was achieved. Moreover, NC was shown to reduce 24 h water absorption compared to controls. These findings show that NC reinforcement improves wood–PRF composites systems for potential sustainable additive manufacturing.