Cardanol-based epoxy resins as a bisphenol-A epoxy alternative in wood-epoxy composite: Performance and extrudability

The forest product sector generates substantial amounts of residue every year, which can be utilized in wood composite manufacturing rather than simply as fuel. However, conventional wood composite adhesives raise health and environmental concerns, highlighting the need for environmentally friendly alternatives. Cardanol-based epoxy (CBE), derived from cashew nutshells, offers a promising biobased substitute for bisphenol-A epoxy (BAE) resin. In this study, we investigated the use of CBE in wood composite manufacturing, along with extrusion processing and potential applications in extrusion-based 3D printing. Cold-pressed panels were made with different ratios of CBE and BPA epoxy for performance evaluations, including curing behaviors, thermal stability, fire performance, mechanical properties, water soaking, artificial weathering, and fungal durability. Among the tested samples, CBE 50 (50% BAE and 50% CBE) exhibited the most favorable performance, combining enhanced thermal stability and reduced heat release with uncompromised mechanical properties (MOR: 11.6 ± 1.5 MPa; MOE: 1374 ± 82 MPa). This formulation was also successfully extruded using a single-screw extruder, proving its possibility of future application of extrusion-based 3D printing.