Abstract: The bismaleimide (BMI) resin, owing to its excellent thermal-oxidative stability and outstanding mechanical properties, has been successfully used for aerospace structure composites. The obvious shortcoming of the BMI resin is brittleness, therefore its application is limited. Resin transfer molding (RTM) process is suitable for the production of large, complex, thick-sectioned structures, which provides good surface quality and increases the parts integration. Traditional toughening methods such as thermoplastic toughening are not suitable for resin for RTM process due to viscosity increase. A kind of novel toughened bismaleimide resin for RTM was fabricated by introducing of an internal chain extension monomer, which presented good processability, such as low viscosity, long pot time (~3 h) and high toughness. The mechanical properties were characterized and indicated that the tensile strength and elongation was 115 MPa and 3.1%, respectively. The flexural strength was 159 MPa. The glass transition temperature of the cured resin was 270 ℃, characterized by DMA. Composites were prepared from carbon fiber and the BMI resin, which exhibited excellent mechanical properties and high retention rate at 230 ℃.

Key words: bismaleimide resin, RTM, composites, mechanical properties