Abstract
SynopsisToughening of cyanate ester resin was carried out by simultaneous curing of cyanate ester resin with radical copolymerization of N-phenylmaleimide, styrene (St) and divinylbenzene (DVB). The influence of radical polymerization on curing behavior of cyanate resin matrix was also studied. The introduction of DVB as a crosslinking agent increased miscibility of the cyanate ester matrix with the modifier, and thereby the fracture toughness for the modified cyanate ester resin was increased by 77% with keeping good flexural properties and high glass transition temperature, compared to the unmodified resin, when 10wt% of N-phenylmaleimide/St (1/1, mol/mol) and DVB (5mol% of the modifier) were added.The observation of phase separation of the modified resins by AFM revealed that toughening was accomplished by the morphology with the modifier-rich phases of 200 to 300 nanometers dispersed in the cyanate ester-rich matrix. Then, from the results of DSC and IR measurements, we found that radical polymerization of PMSD modifier was finished before curing process of 150℃/1h and did not interfere with curing of the cyanate resin matrix each other.
