Effect of Chemical Structure and Network Formation on Physical Properties of Di(Cyanate Ester) Thermosets

Key physical properties of three dicyanate ester monomers, bisphenol A dicyanate (BADCy), bisphenol E dicyanate (LECy), and the dicyanate of a silicon-containing analogue of bisphenol A (SiMCy) were investigated as a function of cyanurate conversion at conversions ranging from approximately 70% to greater than 90% in order to assess the range of applicability of both traditional and more unusual structure–property–process relationships known for cyanate ester resins. A more complete understanding of these relationships is essential for the continued development of cyanate ester resins and their composites for a wide variety of aerospace applications. The degree of cure in each system was determined by differential scanning calorimetry (DSC). The degree of conversion achieved at a given temperature was dependent on the structure of the repeat unit, with SiMCy displaying the highest relative ease of cure. The density at room temperature was found to decrease monotonically with increasing conversion for all ...