On polyetherimide modified bismaleimide resins, 1 Effect of the chemical backbone of polyetherimide

Four kinds of polyetherimides with different diamines were prepared and use d to improve the toughness of bismaleimide resins composed of bis(4-maleimi dediphenyl)methane and o,o'-diallyl bisphenol A. Dynamic mechanical analysi s and scanning electron microscopy were used to characterize the phase stru cture of the modified resins. The modified resins display different phase m orphologies depending on the polyetherimide backbone structure. The results indicate that the degree of phase separation leads to different morphologi es and toughening. The fracture energy (G(IC)) was increased by 300% with t he PIM modified system.