The present invention is a thermosetting bismaleimide resin system comprising a liquid phase and a solid phase where the non-crystallizing liquid phase contains the curing agents diallyl ether of a substantially aromatic radical and a bis(alkenylphenoxy) ether of a substantially aromatic radical along with a substantially aromatic bismaleimide as a particle slurry and optionally a free radical inhibitor. The curing agents are non-crystallizing compositions for use in bismaleimide resin formulations to increase the thermal durability of a cured resin composite as shown by reduced microcracking as measured by reduced weight loss after thermal aging. The present invention resists microcracking over bismaleimide resin systems which incorporate other curing agents or combinations of curing agents. The present invention further provides a bismaleimide resin formulation suitable to make prepregs with reduced crystallization for reduced viscosity supporting improved manufacturing properties and improved tack.