Curing process and properties of BCE/CTBN blends

Carboxyl terminal functionality on liquid butadiene-acrylonitrile (CTBN) is used to improve the mechanical properties of cyanate ester resin by blending with bisphenol A dicyanate ester (BCE). The curing process is based on gel time of BCE/CTBN blends and analysis of differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR). The influence of curing process on structures and properties of BCE/CTBN are studied. Morphology of broken specimens are examined by transmission electron microscopy (TEM). Firstly, it is shown that macroscopical phase separation of BCE/CTBN blends can be improved by two ways, which are applying fast force to the BCE/CTBN blends and pre-polymerizing the BCE before curing process. Secondly, the modified system shows much higher impact toughness. The two ways mentioned above lead to 140% and 102% increase in impact toughness, respectively. Thirdly, it is shown that the modified system includes typical cystiform CTBN particulates, which is beneficial to increasing the flexural strength and impact toughness of BCE.