Enhancement of fire safety in epoxy resin composites through incorporation of microencapsulated diatomite

Abstract

Diatomite (DIA) particles are commonly employed as flame‐retardant additives for polymers, yet their intrinsic inefficiency requires substantial quantities for optimal efficacy. To address this issue, we proposed a novel approach involving the microencapsulation of DIA with polyethylene glycol phosphate (PEGP) to enhance the flame retardancy of epoxy resin (EP). Characterization of the prepared DIA@PEGP utilized scanning electron microscopy with energy‐dispersive x‐ray spectrometry and Fourier transform infrared spectroscopy. The resulting EP composite, DIA@PEGP‐4/EP, achieved a limiting oxygen index of 33.2% and achieved a V‐0 level in vertical combustion tests. Compared to EP, DIA@PEGP‐4/EP demonstrated significantly improved fire performance, with 38.6%, 47.8%, 25.0%, 41.3%, and 60.4% reduction in peak heat release rate, total heat release, peak smoke production rate, total smoke production, and CO yield. Furthermore, the highest FPI value of 0.080 m2·s/kW for DIA@PEGP‐1/EP and the lowest FGI value of 8.734 kW/m2·s for DIA@PEGP‐4/EP, indicate that the incorporation of DIA@PEGP into EP enhances its fire safety. The flame retardancy mechanism of DIA@PEGP‐4 involves the formation of a phosphorus‐containing aromatic carbon layer during EP char formation, capturing radicals in the gas phase during combustion.