Synthesis and characterization of cyanate epoxy composites

Abstract

Anthraquinone dicyanate was prepared by treating CNBr with 1,4 dihydroxy anthraquinone in the presence of triethylamine at -5 to 5°C. The dicyanate was characterized by Fourier transform infrared (FT-IR) spectroscopy. The prepared dicyanate was blended with commercial epoxy resin in different ratios and cured at 120 °C for 1 h, 180 °C for 1 h and post-cured at 220 °C for 1h using diamino diphenyl methane as the curing agent. Castings of neat resin and blends were prepared and characterized by FTIR analysis. The composite laminates were also fabricated from the same composition. The mechanical properties such as tensile strength, flexural strength and fracture toughness were measured as per ASTM D 3039, D 790 and D 5528, respectively. The tensile strength increased with increasing cyanate content (3, 6, and 9%) from 52.1 to 80.1 MPa. The values of fracture toughness also increased from 0.7671 kJ m-2 for the neat epoxy resin to 0.9168 kJ m-2 for the 9% cyanate ester epoxy-modified system. The thermal properties were also studied. The 10% weight loss temperature of pure epoxy was 358 °C and it increased to 381 °C with incorporation of cyanate ester resin. The incorporation of cyanate ester up to a 9% loading level did not affect the glass transition temperature to a very great extent.