Eugenol-Derived Bismaleimide High Performance Resins and Composites Using Diisocyanate as Property Modifier

A new kind of high performance bismaleimide resin with good processability and improved toughness is synthesized by chemical modification of 4,4′-bismaleimidodiphenylmethane (BMI) by eugenol (EG) and different contents of 4,4′-diphenylmethane diisocyanate (MDI). MDI-EG-BMI resins exhibit good thermal stability for its 5% weight loss temperatures around 300 °C and its residue of 41.61% at 900 °C, which are much higher than those of EG-BMI resin. Then, the carbon fiber-reinforced MDI-EG-BMI composites are fabricated. The mechanical properties of the composites matrixed by MDI-EG-BMI resins are better than those by EG-BMI resin. For carbon/MDI-EG-BMI composites, their glass transition temperatures are higher than 300 °C, and their flexural strength, moduli, and toughness are maintained at a range of 217.47–404.36 MPa, 35.12–48.49 GPa, and 1.16–2.63 MJ m ⁻³ respectively; with the contents increasing of MDI in the resin formulation, the flexural properties first increase then decrease; comprehensively the composite with 30 wt% MDI has the best mechanical and thermal properties.