Matrix resins based on bismaleimide–1,2-polybutadienes

Improved thermally stable matrix resins have been obtained by the incorporation of 1,2-polybutadiene in 4,4′-bismaleimidodiphenylmethane. The thermal curing was performed at 185–195°C for 2.5 h and at 230–235°C for 45 min to give tough crosslinked polymers. The thermal curing reaction was monitered using FT-IR and differential scanning calorimetry. Thermogravimetric analysis of the cured resins have shown improved thermal stability up to 490–480°C both in air and nitrogen atmospheres. The char yield obtained in nitrogen at 800°C was in the range of 50–49%. Graphite cloth laminates were prepared and tested. The laminates showed improved tensile strength over to parent bismaleimide. 1,2-Polybutadiene was hydrogenated using 10% palladized-charcoal. The resulting polymer was characterized by using IR and ¹H-NMR, which showed reduction of 15% pendent vinyl double bonds.