Cure mechanism of the 4,4'-(N,N'-bismaleimide)diphenylmethane-2,2'-diallylbisphenol A system

Some kinetic features of reactions occurring at 140-200°C in equifunctional real and model systems (phenylmaleimide-2,2'-diallylbisphenol A and phenylmaleimide-2-allylphenol) were studied by the techniques of IR and 1H and 13C NMR spectroscopy. The equifunctional conversion of maleimide and allyl groups yielding the 1 : 1 addition product takes place in this temperature range. The mechanism of the reaction involving monofunctional reactants differ from that of the cure of the real system because of steric hindrances in 2,2'-diallylbisphenol A, which retard reversible Diels-Alder reactions, and different reactivity of maleimide groups. It was found that the only side reaction in the system of interest is the dehydration of phenolic groups that necessarily involves the 1 : 1 adduct as a reactant.