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.
Jie Zhang,Zongwei Guo,Jinpeng Ma,Lingxiao Song,Guorui Yang,Yuhui Ao,Lei Shang,Ming Li
As an important thermosetting resin, epoxy resin (EP) is widely used in the field of composite materials. Long storage time, rapid curing and low viscosity of one-component EP is ideal for preparing composite materials by vacuum assisted resin transfer molding (VARTM). For this sake, we developed and synthesized a new imidazole thermal latent curing agent, 4,7-diimidazol-2,1,3-benzothiadiazole (BTD-MZ 2 ) with a yield of about 75%. The curing behavior, thermal stability and storage time of the prepared EP system was studied by differential scanning calorimeter (DSC), thermal gravimetric analyzer (TGA), modular compact rheometer (MCR), respectively. DSC results showed that EP/17.5 wt% BTD-MZ 2 had a good latent period at low temperature, and can rapidly cure EP when heated to 150°C. TGA results show that BTD-MZ 2 promoted the formation of carbon residue and the residual carbon rate of EP/17.5 wt% BTD-MZ 2 is as high as 37.9%. MCR results show that the storage time of EP/17.5 wt% BTD-MZ 2 at 60°C can reach 850 min. In addition, it could play a role of catalyst used as co-curing agents with aromatic amines for EP. DSC test showed that the addition of 5 wt% BTD-MZ 2 reduced the activation energy of EP/4,4′-diaminodiphenylmethane (DDM) and promoted the curing reaction.