A new bismaleimide system for resin transfer molding

Abstract A new bismaleimide (BMI) resin system, designated 4503A, suitable for resin transfer molding (RTM) has been developed. It is prepared by employing allyl methyl phenol and diallyl bisphenol A as reactive diluents for BMI. The processing properties of 4503A were investigated by time‐temperature‐viscosity curves, gel characteristics, and differential scanning calorimetry (DSC). Data show that the injection temperature of 4503A prepolymer can be as low as 75°C, while its viscosity is only 0.34Pa · s. In addition, after being maintained at 75°C for 12h, the viscosity is <0.95Pa · s. The cured 4503A resin has a glass transition temperature (T_g) and a heat deflection temperature (HDT) of 266 and 232°C, respectively; properties include tensile strength of 81MPa, flexural strength of 108MPa, and G_1C of 213J/m². Other properties of a composite based on 4503A system and woven glass cloth are also discussed. Regarding short beam shear (SBS) strength, for tests at 150 and 180°C, 80 and 61% of the original room temperature (RT) strength is retained. A similar strength retention (86 and 68%) is noted for flexural properties.