Biomass-derived epoxy resin and its application for high-performance natural fiber composites

The development of bio-based materials with superior comprehensive properties from biomass resources remains a significant challenge, providing an alternative to conventional petroleum-based materials. This study explores the lignin-derived vanillyl alcohol epoxy (VAE) resin-containing mono and di (m&d) epoxy structure as an adhesive to develop environment-friendly natural fiber-reinforced composites to reduce the carbon footprint. The synthesized m&dVAE containing mono and di-epoxidized (m&d) aromatic rings, when cured with 4, 4´-diaminodiphenyl methane (DDM) hardener, exhibits higher record tensile strength ∼124.0 ± 8.43 MPa and tensile modulus ∼2.88 ± 0.35 GPa compared to a commercial petroleum-based epoxy, diglycidyl ether bisphenol A (DGEBA) thermoset. Additionally, it demonstrated higher adhesion shear strength (∼19.16 ± 0.58 MPa) with cellulose nanofibers film than DGEBA. Moreover, fabricated green composite possesses excellent flexural strength of ∼203.72 ± 2.08 MPa and stiffness of ∼11.58 ± 0.38 GPa than the petroleum-based thermoset composite. The composite’s fracture surface morphology shows that the resin and fibers have good interfacial adhesion. Notably, the sustainable composite showed good hydrophobicity and an excellent heat-resistant index of 144.4°C. The m&dVAE resin can be an alternative to petroleum-based resins as an adhesive, and its environment-friendly sustainable composite could be a promising candidate to replace synthetic materials for high-performance structural applications.