Synthesis and Characterization of 1,1-bis(3-Methyl-4-Cyanatophenyl) Cyclohexane-Epoxy-Bismaleimide Matrices

Abstract

A new cyanate ester monomer, 1,1-bis(3-methyl-4-cyanatophenyl) cyclohexane has been synthesized and characterized. Epoxy modified with 4, 8 and 12% (by wt) of cyanate ester were made using epoxy resin and 1,1-bis(3-methyl-4-cyanatophenyl) cyclohexane and cured by using diaminodiphenyl-methane. The cyanate ester modified epoxy matrix systems were further modified with 4, 8 and 12% (by wt) of bismaleimide ( N,N′-bismaleimido-4,4′-diphenyl methane). The formation of oxazolidinone and isocyanurate during cure reaction of epoxy and cyanate ester blend was confirmed by IR spectral studies. Bismaleimide-cyanate ester-epoxy matrices were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and heat deflection temperature (HDT) analysis. 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 (CE) into epoxy resin improves the toughness and flexural strength with reduction in tensile strength and glass transition temperature, whereas the incorporation of bismaleimide (BMI) into epoxy resin enhances the mechanical and thermal properties according to its percentage content. However, the introduction of both CE and BMI enhances the values of thermo-mechanical properties according to their percentage content. DSC thermogram of cyanate ester modified epoxy and BMI-modified epoxy show an unimodal reaction exotherms. The thermal degradation temperature and heat distortion temperature of the cured BMI-modified epoxy and CE-epoxy systems were increased with increasing BMI content. The morphology of the BMI modified epoxy and CE-epoxy systems were also studied by scanning electron microscope.