Mechanical properties of reactively flame retarded cyanate ester/epoxy resin blends and their carbon fibre reinforced composites

Abstract

Cyanate ester/epoxy resin (CE/EP) carbon fibre reinforced composites consisting of diglycidyl ether of bisphenol A (DGEBA) and novolac type cyanate ester (CE) were prepared and reactively flame retarded using epoxy functional adduct of DGEBA and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). Effect of cyanate ester and flame retardant (FR) ratio was determined on matrix viscosity, matrix and composite glass transition temperature (Tg), as well as composite mechanical properties including storage modulus, tensile, bending, interlaminar shear and Charpy impact properties. Although the epoxy resin (EP) and FR decreased the Tg, even the flame retarded CE/EP blends had at least 22 °C higher Tg than the benchmark DGEBA composite. As for the mechanical properties, as a result of higher interlaminar shear strength suggesting better fibre-matrix adhesion, the CE/EP blends managed to over-perform the reference CE in most cases: The 2% phosphorus (P)-containing CE/EP composite had 25% higher tensile strength than the CE reference. The bending strength of the blends remained in the same range as the reference, while the impact resistance significantly increased in comparison to CE, especially in flame retarded composites.

Keywords

• Mechanical properties
• Flame retardancy
• Cyanate ester
• Epoxy resin
• Carbon fibre reinforced compos