Intumescent flame retardants with simple ionic structure are used in vinyl ester resin

In this study, ZP was synthesized via a straightforward ion exchange reaction and utilized as both an acid source and a gas source for the preparation of intumescent flame-retardant vinyl ester resin (VER). The chemical structure of ZP was characterized using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The flame-retardant performance of the composites was systematically evaluated through limiting oxygen index (LOI), vertical burning (UL-94), and cone calorimetry (CC) tests. The results demonstrated that the VER-ZP17.5 composite achieved an LOI value of 29.6 % and attained a V-0 rating in the UL-94 test. Furthermore, the peak heat release rate (PHRR) and total heat release (THR) were reduced by 32.7 % and 35.7 %, respectively. Analysis and discussion of the flame-retardant mechanism revealed that ZP effectively promoted the formation of an intumescent char layer, significantly inhibiting flame propagation and reducing heat transfer to the internal matrix during combustion. This study provides new insights and experimental evidence for the development of high-performance intumescent flame-retardant composites.