Preparation and characteristics of reactive blends of phosphate-containing maleimide and epoxy

Three kinds of phosphate-containing maleimide(PMI) monomers, namely diethyl (4-(N-maleimido) phenyl) phosphate (4P) diphenyl (4-(N-maleimido) phenyl) phosphate (PP) and diethyl (2,6-dibromo-4-(N-maleimido)phenyl) phosphate (BrP), were synthesized and blended with a phenol-novolac type of epoxy so as to study their potential as reactive flame retardants. Thermal reaction of these blending systems had been discussed. Mechanical and thermal properties of blends had also been analysed. It was expected that with an increase in the PMI content in the blending system, the Michael-addition reaction would take place more and easily. Increasing the PMI contents reduced the storage modulus, the Tg and the tensile strength, however good thermal stability was maintained. The flame retardancy of all the phosphate-containing epoxy systems was promoted significantly by increasing the PMI content. Besides, the PMI with halogen atom may combine the flame retarding mechanism of gas-phase and solid-phase to promote their flame retardancy.