Tetrafunctional bio-based epoxy resin derived from divanillin with excellent heat resistance, mechanical and flame-retardant properties

Abstract

Developing high-performance epoxy resins with excellent heat resistance, mechanical and flame-retardant properties from widely available biomass resources is crucial for meeting increasing performance demands in cutting-edge applications and achieving carbon neutrality. In this study, two tetrafunctional bio-based epoxy monomers (AEDV-EP and PEDV-EP) containing biphenyl structure were designed and synthesized based on the vanillin-derived divanillin, and cured with 4,4-diaminodiphenylmethane (DDM). The results showed that the cured epoxy resins AEDV-EP/DDM had glass transition temperatures (T_g) of 214 ℃, and PEDV-EP/DDM exceeded 290 ℃, both significantly higher than DGEBA/DDM (166 ℃). Similarly, the mechanical properties of AEDV-EP/DDM and PEDV-EP/DDM are also superior, with tensile strengths increased by 19.2 % and 36.0 %, respectively, compared to DGEBA/DDM. In addition, the heat release capacity (HRC), peak heat release rate (PHRR), and total heat release rate (THR) of AEDV-EP/DDM and PEDV-EP/DDM are significantly lower than those of DGEBA/DDM. They have also reached the V0 level of the vertical burning test (UL-94), demonstrating excellent intrinsic flame-retardant properties. Notably, the viscosity of AEDV-EP at room temperature is as low as 0.2 Pa·s, showing superior processability, which is extremely rare among high-performance epoxy resins. This study paves a promising path for preparing more practical high-performance bio-based epoxy resins, which show great potential for applications in aerospace, rail transportation, and microelectronics.