The effect of bis allyl benzoxazine on the thermal, mechanical and dielectric properties of bismaleimide–cyanate blend polymers

Abstract

Thermosetting terpolymers composed of bis allyl benzoxazine (Bz-allyl), cyanate ester (BADCy) and 4,4′-bismaleimidodiphenyl methane (BMI) were prepared via co-curing reactions. The curing kinetics of Bz-allyl/BMI/BADCy were investigated via non-isothermal DSC at different heating rates using the Flynn–Wall–Ozawa method. The dielectric, thermal and mechanical properties of Bz-allyl/BMI/BADCy terpolymers were systemically investigated in detail through mechanical measurement, scanning electron microscopy (SEM), dynamic mechanical analysis (DMA) and thermo-gravimetric analysis (TGA). The results show that a suitable addition of Bz-allyl can enhance the impact strength and flexural strength as well as reduce the dielectric constant and the dielectric loss of BMI/BADCy. The dynamic mechanical analysis reveals that the cross-link density of the blend is higher than BMI/BADCy. The higher crosslinking density of the terpolymer led to good thermal stability of the terpolymer. Scanning electron microscopy analysis shows the distinct characteristics of ductile fracture of the blends. All of these changes in properties are closely correlated to the copolymerization between Bz-allyl and BMI/BADCy, which could form an interpenetrating polymer network in the system.