Blends of bismaleimide resins and bis(allyl phenyl) esters

The effect of reactive diluents such as bis(4‐allyl 2‐methoxyphenyl) adipate (AEg), bis(4‐allyl 2‐methoxyphenyl) terephthalate (TEg), and bis(o‐allyl phenyl) sebacate (APS) on curing characteristics and thermal behaviour of bis(4‐maleimidophenyl) methane (BM) chain‐extended with 4,4′‐diaminodiphenyl methane (DADPM) is described. Samples containing 5, 10, 15, 20, 25, 35, and 45 wt.‐% of these reactive diluents and bismaleimide resin were prepared. Addition of APS, AEg, and TEg affected the curing exotherm of bismaleimides. The thermal stability of bismaleimide decreased on addition of APS or AEg, but in presence of TEg an improvement in char yield at 800°C was observed. Glass fibre reinforced laminates fabricated from bismaleimide resin containing 10% APS exhibited interlaminar shear strength of 20.8 N/mm2 and flexural strength of 541 N/mm2.