A new Schiff base functionalized dicyanate ester was synthesized and the monomer was characterized by FTIR, 1H‐NMR, 13C‐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 (GIC = 104–136 J/m2) 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 δ 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., 2009. © 2009 Society of Plastics Engineers

A novel allyl functionalized dicyanate ester resin bearing sulfoxide linkage was synthesized. The monomer was characterized by Fourier Transform Infrared (FT-IR) Spectroscopy, 1 H-, and 13 C Nuclear Magnetic Resonance (NMR) spectroscopy and elemental analysis. The monomer was blended with bismaleimide (BMI) at various ratios in the absence of catalyst. The cure kinetics of one of the blends was studied using differential scanning calorimetry [nonisothermal] and the kinetic parameters like activation energy (E), pre-exponential factor (A), and the order of the reaction (n) were calculated by Coats-Redfern method and compared with those calculated using the experimental Borchardt-Daniels method. The thermal stability of the cured dicyanate, BMI, and the blends was studied using thermogravimetric analyzer. The initial weight loss temperature of dicyanate ester is above 3808C with char yield of about 54% at 8008C. Thermal degradation of BMI starts above 4638C with the char yield of about 68%. Inclusion of BMI in cyanate ester increases the thermal stability from 419 to 4418C.

A range of Schiff base functionalized cyanate esters and their precursors were prepared in high yield and characterized using Fourier transform infrared, 1 H-nuclear magnetic resonance spectroscopy and elemental analysis. One of the dicyanates was blended with bismaleimide (BMI) at various proportions to increase the toughness of BMI. The thermally initiated polymerization was studied by differential scanning calorimetry. Cure studies reveal that BT4 (1 : 1 weight ratio of cyanate ester and BMI) was more compatible. The thermal stability of the bismaleimide-triazine (BT) resins was studied using TGA. The 10% weight loss temperatures in N 2 were above 380 1 C with char yield in the range of 72-86%. Moisture absorption of these blends was in the range of 0.3-2%. Chemical resistance of the BT resins was also studied towards acids, alkali and ketone solvent.

A series of new bisphenols containing sulfoxide has been prepared from various substituted phenols and thionyl chloride using AlCl 3 as catalyst. These bisphenols were converted to their respective cyanate esters by reacting with cyanogen bromide. The structures of all the five bisphenols and cyanate esters have been confirmed by FTIR, 1 H NMR, and 13 C NMR spectral methods and elemental analysis. The thermal properties of cyanate ester resins were studied by DSC and TGA. The glass transition temperature of the cured sulfoxide bridged cyanate esters are in the range of 181-2368C. The Cy(e) cyanate ester shows high thermal stability due to linked interpenetrating polymer networks formed by allyl functionality. The initial thermal degradation temperature starts above 3408C. The char yield is in the range of 38-54%. The limiting oxygen index value is the range of 32.

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