Dynamic mechanical analysis was conducted on specimens prepared from cyanate ester (CE) and epoxy (EP) resins cured together at various mass compositions. Increase of amount of epoxy resin in composition was shown to have a disadvantageous effect on glass transition temperature (T g ). It was shown that post-curing procedure was needed to produce a polymer matrix with a single glass transition relaxation, but increase in post-cure temperature up to 250°C resulted in slight reduction in T g for epoxy/ cyanate copolymers. TG results proved that the presence of epoxy resin reduces thermal stability of the cyanate/epoxy materials. The neat CE and EP/CE systems containing 30 wt% of epoxy resin were modified using epoxy-terminated butadiene-acrylonitrile rubber (ETBN) and polysiloxane core-shell elastomer (PS). The scanning electron microscopy (SEM) results showed the existence of second phase of ETBN and PS modifiers. Only in the case of EP/ CE composition modified with ETBN, well-dispersed second phase domains were observed. Analysis of SEM images for other CE-and EP/CE-modified systems revealed the formation of spherical aggregates.

The cyanate ester (CE) and epoxy (EP) resins were cured together at various mass compositions. The curing behavior of CE and CE/EP systems was studied by means of differential scanning calorimetry (DSC) in nonisothermal conditions. The DSC measurements indicated that the curing reactions were dependent on the stoichiometric ratio of the mixtures and showed the dilution effect of the EP resin in the cyclotrimerization of the catalyzed CE resin. The CE and CE/EP (70/30) systems were modified using reactive liquid butadiene-acrylonitrile copolymer (ETBN) and polysiloxane core-shell (PS) elastomer. The influence of ETBN and PS on the curing process and glass transition temperature (T g ) of CE/EP systems was determined. The impact resistance characteristics of the completely cured systems indicated the influence of the modifiers and the EP content in the mixtures on its impact resistance.