Vanillin-derived epoxy resin as a high fracture toughness high stiffness matrix for carbon fibre reinforced structural composites

Abstract

The following study cements vanillin’s position as a leading replacement for BPA-based epoxy resins in high performance epoxy–amine composite applications. Diglycidyl ether of vanillyl alcohol (DGEVA) is cured with a high-performance aerospace grade crystalline diamine hardener 4,4 diaminodiphenyl sulfone (4,4-DDS) yielding a resin with a T_g of 140 °C according to DMA, high bending stiffness of 3.84 ± 0.02 GPa, and high mode I fracture toughness of 1.33 ± 0.23 MPa m^1/2, as evidenced by ASTM standard tests. Initial kinetic and rheological evaluation of DGEVA–DDS highlights its potential to act as a drop-in epoxy system for many industrial composite manufacturing processes with minor processing adjustments. Resin is characterized by means of cure kinetics, thermomechanical properties and physical properties deciphering a route for carbon fibre reinforced composite manufacturing. The results show superior performance of the neat DGEVA–DDS system in mechanical tests including up to 38% greater strength, 60% stiffness, 160% fracture toughness, and minor increases when translated to composite materials as compared to BADGE–DDS.