Bio-based thermosetting bismaleimide resins using eugenol, bieugenol and eugenol novolac

摘要

5,5'-Bieugenol (BEG) and eugenol novolac (ECN) were synthesized by the oxidative coupling reaction of eugenol (EG) and the addition-condensation reaction of EG with formaldehyde, respectively. The EG, BEG and EGN were prepolymerized with 4,4-bismaleimidediphenylmethane (BMI) at 180℃ and then compression-molded at finally 250 ℃ for 6h to produce cured EG/BMI (EB), BEG/BMI (BB) and EGN/BMI (NB) resins with eugenol/maleimide unit ratios of 1/1, 1/2 and 1/3. The FT-IR analysis of EBs and ~(13)C NMR analysis of the model reaction product of EG/N-phenylmaleimide (PM1) 1/3 at 200 ℃ for 12 h suggested that the ene reaction and subsequent Diels-Alder/ene reactions mainly occurred for EBs. The FT-IR analyses of BBs and NBs supported the occurrence of ene reaction and subsequent thermal addition copo-lymerization in a similar manner to the well-known curing reaction of 2,2'diallylbisphenol A and BMI. The glass transition temperature (T_g) and 5% weight loss temperature (T_5) of the cured resin increased with increasing BMI content, and EB 1/3 showed the highest T_z 377℃ and T_5 475 ℃. The flexural strengths and moduli of EBs and NBs were higher than those of BBs, and EB 1/2 showed the most balanced flexural strength and modulus (84.5 MPa and 2.75 GPa). The FE-SEM analysis revealed that there is no phase separation for all the cured resins.