EUTECTIC MIXTURE OF 2 BISMALEIMIDE MONOMERS - THERMAL AND MECHANISTICSTUDY IN THE MOLTEN STATE

Differential scanning calorimetry analysis of two bismaleimide monomer s (N-N-diphenylmethane-4,4'-bismaleimide and m-phenylenebismaleimide) mixed in different proportions has enabled a phase diagram to be const ructed. There is a relationship between the melting and solubility of each constituent of the binary system via the different liquid and sol id phases. The concept of a eutectic mixture having special thermal pr operties has thus been demonstrated. The eutectic melting temperatures are very interesting because they are much lower than that of the com pound with the lowest melting point, making easier the use of these mo nomers in the molten state. In addition, the reduction of the temperat ures of crosslinking onset becomes maximal in these systems at the eut ectic point, at which point there is a unique and perfectly homogeneou s melting. In this unique liquid phase, the two monomers can combine t o form the network after a copolymerization reaction. Once the network forms, m-phenylenebismaleimide radicals that are more highly stabiliz ed by resonance are more reactive in the initial stages of the copolym erization reaction. (C) 1997 Elsevier Science Ltd.