Zinc Borate as an Alternative Non-halogen Flame Retardant System in Epoxy Resins

Abstract

The most important disadvantage of epoxy resins is their low thermal resistance and fire behavior. Flame retardants (FR) of various types are therefore used. Tetrabromobisphenol A (TBBPA) is the retardant frequently used in epoxy resins. However, TBPPA may pose an environmental risk and so efforts appear to replace it with a non-halogen alternatives. The aim of this work is to compare two epoxy/glass composites containing different flame retardants - conventional TBBPA and a novel halogen-free retardant based on zinc borate (2ZnO·3 B₂O₃·3H₂O). Thermal stability of both composites was studied by TGA and DSC and the UL 94 test was used to evaluate their flammability. In addition, dissipation factor and dielectric permittivity at 50 Hz and 1 MHz were measured. The new retardant can be recommended for substitution of TBBPA in conventional epoxy resins even though it is used in larger amounts.