Influence of Melamine Formaldehyde Content on the Mechanical and Flame-Retardant Properties of Polyester Resin Systems

Abstract

The present study investigates the development of halogen-free flame-retardant polyester coatings through the incorporation of melamine formaldehyde (MF) resin as a multifunctional crosslinking and char-promoting agent. The incorporation of MF significantly improved flame-retardant performance, increasing flame resistance from 42% for neat polyester to 89% for the polyester/MF composite containing 20 wt.% MF. Enhanced thermal stability and curing efficiency were attributed to the formation of a highly crosslinked thermoset architecture and the nitrogen-rich triazine structure of MF, which facilitated condensed-phase char formation and inhibited flame propagation. Among the investigated formulations, the polyester/MF (90:10) system exhibited the most favorable balance between mechanical integrity and fire resistance. The findings demonstrate that MF resin is an effective halogen-free flame-retardant modifier for polyester coatings, enabling simultaneous enhancement of thermal performance and combustion resistance while maintaining acceptable mechanical properties. These results highlight the potential of polyester/MF hybrid networks for advanced protective coating and fire-safety applications.