Enhancement of the processibility of bismaleimide resins via copolymerisation with allyl organo-boron compounds

The main objective in modifying bismaleimide (BMI) is to improve its processibility and fracture toughness whilst retaining its heat resistance and good hygrothermal stability. In this work, a new series of allyl compounds containing boron (coded XB, XA, BQ), were prepared by esterification of allyl phenol compounds and boric acid. These structures were characterized by FTIR. The reactivity and curing behaviour of BMI resin systems modified by boron-containing compounds were investigated by gel time and differential scanning calorimetry. The thermal stability and thermal mechanical properties of the cured copolymer were evaluated. No weight loss was observed when the copolymer was heated to 465°C in a nitrogen atmosphere. The char yields at 800°C in nitrogen are more than 54%, the highest of them being 60%. The mechanical properties of the neat resin and glass-fibre-reinforced composites are also discussed.