Mechanical Properties of High Temperature Cyanate Ester/BMI Blend Composites

A new Schiff base functionalized dicyanate ester was synthesized and the monomer was characterized by FTIR, H-1-NMR, C-13-NMR and elemental analysis techniques. This prepared dicyanate ester with catalyst was then blended with BMI resin at different ratios by solution technique. The composites were made by impregnating the fibers with the blend solution followed by curing at various time-temperature schedules. The mechanical properties of the blend composites were tested. The fiber volume fraction of the composites were found to be in the range 41 +/- 3%. The mechanical properties such as tensile modulus (32-35 GPa), flexural modulus (56-59 GPa) and Mode I fracture toughness (G(IC) = 104-136 J/m(2)) and impact response (1,121-1,218 J/m) were found to increase with increasing cyanate ester content in the Cy/BMI blends. From the DMA study it was observed that as the cyanate content increases from 3 to 9% in the blend the tan delta value increases from 0.112 to 0.126 and the storage modulus decreases from 24,750 to 22,870 MPa indicating that the crosslink density of the blends decreases. The SEM analysis shows the absence of phase separation. Moisture absorption and chemical resistance of the blend composites increase with increasing cyanate content. POLYM. COMPOS., 30:782-790, 2009. (C) 2009 Society of Plastics Engineers