Epoxy-modified cyanate ester resin and its high-modulus carbon-fiber composites

Epoxy E51-modified bisphenol A dicyanate (BADCy) and its high-modulus carbon fiber (M40) reinforced composites were prepared in this research. The carbon-fiber composites were prepared by autoclave molding. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy of BADCy-E51 blend systems showed that polycyclotrimerization of BADCy primarily took place at low temperature. Epoxy group reacted with triazine ring group and produced oxazolidinone at high temperature. The data of mechanical properties, water absorption, and heat deflection temperature (HDT) of cured castings showed that the matrix system containing 95 wt% BADCy and 5 wt% E51 had optimum characteristics. Scanning electron microscopy (SEM) analysis of M40 fiber and the fracture surfaces of M40/BADCy-E51 composite displayed that the adhesion between M40 fiber and BADCy was good though the surface of M40 was inert. The high retention of mechanical properties of M40/BADCy-E51 composite after long-term exposure to environmental conditions indicated that the M40/BADCy composite was suitable for space applications.