Bio‐based hydroxymethylated eugenol modified bismaleimide resin and its high‐temperature composites

Hydroxymethylated eugenol (MEG) and poly (hydroxymethylated eugenol) (PMEG) were synthesized by the condensation reaction of eugenol (EG) with formaldehyde. The different contents of MEG and PMEG were used to modify 4,4′‐bismaleimidediphenylmethane (BMI). The cured MEG‐BMI resins exhibit good thermal stability evidenced by its 5% weight loss temperatures above 407°C and its residue above 39.4% at 800°C under nitrogen. For carbon/MEG‐BMI composites, their glass transition temperatures were around 400°C; their flexural strength and moduli were maintained at a range of 488.87–575.47 MPa and 48.84–60.26 GPa, respectively. With the increasing content of BMI in the resin formulation, the flexural properties decreased; comprehensively the composite with the eugenol/maleimide unit ratio (1:0.3 mol) had the best mechanical and thermal properties, meanwhile its renewable carbon content was as high as 57.80%. As a new candidate of high temperature thermosetting resin, MEG would find promising applications for advanced composites' matrice. Hydroxymethylated eugenol (MEG) and poly‐MEG (PMEG) were synthesized and used to modify BMI in order to possess good processability, high heat resistance and excellent mechanical properties. Glass transition temperatures of the carbon fiber‐reinforced MEG‐BMI composites arearound 400℃. Flexural properties of the composites based on MEG‐BMI are significantly improved compared to those of the composites based on EG‐BMI.