Cure behavior of epoxy‐cyanate ester blend in composite systems: Evaluation studies in neat resin cast by thermal and FTIR techniques

Abstract

The post‐cure behavior of a commercially available DGEBA‐based epoxy modified cyanate ester resin (1,1‐bis (4‐cyanato phenyl) ethane) was investigated by thermo analytical techniques and Fourier Transform Infrared (FTIR) spectroscopy. Thermally initiated resin cure was carried out at 170°C/1 h followed by 180°C/2 h. Two different post‐cure procedures, (PCPs), PCP‐I (210°C/2 h + 250°C/1 h) and PCP‐II (280°C/3 h), were independently followed for the cured resin material. Dynamic mechanical analysis (DMA) characterization of the resin casts indicated significant lowering of glass transition temperature (Tg), by about 35°C in PCP‐II casts in comparison with PCP‐I, though the former was post cured at higher temperature. However, the PCP‐II specimens recorded considerable enhancement in storage modulus values at room temperature and above till about the Tg region. FTIR spectroscopic studies of the resin cast support the formation of both cyanurate triazine ring (1563 cm−1, 1368 cm−1) and oxazolidinone ring (1736 cm−1) for the PCP‐I resin cast while in the PCP‐II specimens the former, namely the cyanurate formation was found to be absent. The absence of rigid cyanurate triazine rings in PCP‐II was further strengthened by the tanδ max values observed in these resin casts by DMA. The DMA and differential scanning calorimetry gave comparable Tg values for both the PCP‐I and PCP‐II resin casts. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Miscibility, Microstructure, and Thermal and Dielectric Properties of Reactive Blends of Dicyanate Ester and Diamine-Based Benzoxazine

“…In the coreaction of cyanate ester and epoxy, , the electron-rich ether linkage of the triazine structure attacks the epoxy group, forming alkyl cyanurate which then rearranges to alkyl isocyanurate. Combining the DSC (Figure ) and IR data (Figure ) as well as the chemistry of cyanate ester and epoxy, − we propose the following reactions in the blends. The first is the cyclotrimerization of cyanate ester catalyzed by the residual phenolic groups in benzoxazine.…”

High-Temperature-Performance Cyanate Ester Composites with Carboranes

“…Further, the disappearance of the OH peak from diols on carborane at 3249 cm –1 and the appearance of imine linkage vibration at 1649 cm –1 provide evidence of the formation of iminocarbonate linkages between PD carborane and CE resin. The reaction between epoxy and cyano groups is well-studied and sufficiently reported in the literature in epoxy–CE thermoset blends. − Carboranes are 3D aromatic polyhedral boron cage structures which are highly resistant to thermal degradation and chemical attack. The strong electron-withdrawing nature of the o -carborane cage enables the synthesis of various substitutes on the C vertices, leaving the cage intact .…”

Cyanate Ester—Epoxy Blends for Structural and Functional Composites

“…They also found out that the CTE of a CE–EP blend decreases with the increase in CE concentration. The effect of a postcuring cycle on thermal properties of the blend system was studied by Sekhar et al As postcuring temperature increases, the amount of triazine structure decreases, which leads to the reduction in T g . The influence of alkyl chain length on blend properties was analyzed by Shakthidharan et al They noticed that the CE containing an even number of carbon atoms in two aromatic rings is thermally stable than the CE containing an odd number of carbon atoms.…”