Cure monitoring of catalysed cyanate ester resins

The cure behaviour of two bisphenol A-based cyanate ester resins, AroCy B10 and B30, catalysed by copper acetylacetonate and nonylphenol was studied. For this purpose, differential scanning calorimetric (DSC) and rheological measurements were carried out at temperatures between 130 and 170 degrees C . The cyanate conversion profiles are fitted with a second-order rate law i n the kinetically controlled regime where a good time-temperature superposi tion is attained. However, it is necessary to add an empirical kinetic term to give a good description of the entire range of curing. Simultaneously, times to gelation and vitrification have been determined by dynamic rheolog ical measurements over the same temperature range. The corresponding conver sions have been calculated by correlation of rheological and DSC data, the vitrification conversion being slightly higher for the prepolymer. Independ ent: of the cure temperature, a good correlation between cyanate conversion and glass transition temperature was obtained. The isothermal time-tempera ture-transformation diagrams for these systems are constructed from the kin etic model and the Di Benedetto equation, and show good agreement with the experimental data. (C) 2000 Society of Chemical Industry.