The Effect of a Copper(II) Chelate Coordination Compound on the Combustibility and Fire Behavior of Epoxy-Amine Composite Materials

Abstract

This study investigates the impact of a novel copper(II)-based flame retardant on the combustibility and fire risk of epoxy composites. The flame retardant is a chelate-type coordination compound of copper(II) chloride and diethylenetriamine (deta) – [Cu(deta)₂]Cl₂ – and was synthesized through the direct reaction of CuCl₂ and polyethylenepolyamine (pepa). When incorporated into epoxy resin, the synthesized coordination compound exhibites bifunctional properties, acting as both a flame retardant and a curing agent. Epoxy composites containing [Cu(deta)₂]Cl₂ are significantly less combustible, as demonstrated by a decrease in the maximum temperature of the gaseous combustion products and the mass loss of composite samples due to combustion. The flammability of the synthesized composition was evaluated using the vertical burning method in accordance with the UL 94 standard, and the composition met the criteria for the V-1 class. Incorporating the synthesized flame retardant-hardener into the epoxy resin reduces smoke emission intensity during burning and smoldering. The increased fire resistance of the modified compositions is due to the formation of Cu–N coordination bonds in the polymer matrix and the catalytic effect of copper-containing centers on carbonization and oxidation processes. This is in addition to the formation of a dense, carbonized protective layer during thermal decomposition. These results confirm the potential of using copper(II) chelate coordination compounds as multifunctional components in epoxy systems that combine the roles of curing agent and flame retardant. This opens up opportunities for creating a new generation of polymer materials with enhanced fire safety for various applications.