Structural design strategy of biobased propargyl ether-functionalized epoxy monomer to access low viscosity resin with excellent heat resistance and mechanical properties for advanced composite via VARTM

High performance biobased epoxy resin with low viscosity is important for preparing fiber-reinforced polymer composites via vacuum-assisted resin transfer molding (VARTM). Herein, a novel biobased propargyl ether-functionalized epoxy monomer (BPBO) with low viscosity (0.07 Pa·s) was designed and synthesized from renewable eugenol, and then it was combined with methyl nadic anhydride (MNA) to produce a new epoxy system (BPBO/MNA) with excellent properties. The curing behaviors and integrated performances were systematically researched and compared with those of petrochemical-based commercial diglycidyl ether of bisphenol A (DGEBA) type epoxy resin (DGEBA/MNA). BPBO/MNA shows better thermal and mechanical properties than DGEBA/MNA. Specifically, the glass transition temperature ( T g ) and the flexural strength of BPBO/MNA resin are as high as 242 °C and 176.2 MPa, about 47 °C and 16.8 % higher than those of DGEBA/MNA resin, respectively, and both of them are the highest among those of eugenol-derived epoxy resins reported so far. The nature behind these outstanding integrated performances is attributed to the unique cross-linked structure of BPBO/MNA that originated from the ring opening polymerization of epoxy with anhydride and the polymerization of aryl propargyl ether groups. Moreover, carbon fiber reinforced composite with attractive performance was developed by taking BPBO/MNA as the resin matrix via VARTM process. This work presents a simple and unique strategy to prepare high performance biobased epoxy resin with low viscosity for advanced composites.