Effects of Anhydride Hardener on Performance of a Glycerol-Derived Bio-Epoxy Resin for Advanced Composites Manufacturing

This study systematically evaluates the physical, mechanical and thermal performance of glycerol triglycidyl ether-based bio-epoxy resins to assess their suitability as sustainable alternatives for high-performance composite applications. A Taguchi (L12)-Gray relational analysis optimized the bio-epoxy formulation for high-performance composites. The optimal formulation was identified as glycerol-based bio-epoxy resin with low viscosity (BE1) combined with 5-methyl-5-norbornene-2,3- dicarboxylic anhydride (MNA) hardener at stoichiometric ratio and 1.5 wt.% catalyst. ANOVA results showed that resin type, MNA, and initiator contents contributed 18.2%, 31.8% and 4.5% to overall performance, respectively. The optimized bio-epoxy resin formulation exhibited a saturated water absorption of 2.06% and crosslink density of 0.002 mol/cm 3 . Tensile, compressive and flexural strengths of 60, 106 and 100 MPa, respectively were achieved, with corresponding moduli of 3.38, 2.71 and 3.25 GPa, respectively. The glass transition temperature was 136 o C, linear thermal expansion coefficient was 105 μm/m. o C and thermal decomposition temperature was 306 o C. When manufacturing process demanding high-viscosity resin system, the optimized formulation consisted of a high viscous glycerol-based bio epoxy resin (BE5) cured with MNA hardener at stoichiometric ratio and 1.5 wt.% catalyst. The optimized bio-epoxy provides a sustainable alternative to petroleum-based resins, supported by a scalable optimization framework for high-performance composite manufacturing.