Preparation and characterization of epoxy-cyanate ester interpenetrating network matrices/organoclay nanocomposites

The interpenetrating network matrices of epoxy and cyanate ester was made using epoxy resin and three different cyanate ester monomers namely 1,1-bis(3-methyl-4-cyanatophenyl) cyclohexane, bisphenol dicyanate and 1,3-dicyanatobenzene and cured by using diaminodiphenylmethane. Epoxy modified with 4, 8 and 12% (by weight) of cyanate esters were made. Cyanate ester modified epoxy matrices were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and heat deflection temperature (HDT) analysis. Thermal studies indicate that the introduction of cyanate ester into epoxy resin improves the thermal degradation studies at the expense of glass transition temperature. DSC thermogram of cyanate ester modified epoxy show unimodel reaction exotherms. The matrices, in the form of castings, were characterized for their mechanical properties namely, tensile strength, flexural strength and unnotched Izod impact test as per ASTM methods. Mechanical studies indicate that the introduction of cyanate ester into epoxy resin improves the toughness and flexural strength with reduction in tensile strength. The morphology of the epoxy and cyanate ester-epoxy systems were also studied by scanning electron microscope (SEM). The organophilic montmorillonite clay-epoxy and cyanate ester-epoxy nanocomposites are prepared and the formation nanocomposites are evaluated by X-ray diffraction (XRD), dynamic mechanical analysis (DMA) and SEM. Copyright (C) 2003 John Wiley Sons, Ltd.