Preparation of mesoporous silica-LDHs system and its coordinated flame-retardant effect on EVA

Abstract

This paper mainly studies synergistic flame-retardant effects and smoke suppression properties of mesoporous silica-LDHs system on the ethylene-vinyl acetate copolymer (EVA). The mesoporous silica-LDHs/EVA composites were prepared based on EVA as resin matrix, mesoporous silica-LDHs as flame-retardant composites. The flame-retardant and thermal degradation properties of the composites were characterized by limiting oxygen index (LOI), cone calorimeter test, scanning smoke density test (SDT), electronic microscopy (SEM) and thermogravimetry–Fourier transform infrared spectrometry (TG-IR) analysis. Remarkably, addition of certain amount of mesoporous silica-LDHs could evidently increase LOI values. The heat release rate and the total heat release of the composites were much lower than of pure EVA. The SDT results showed that the composites containing mesoporous silica-LDHs produced less smoke than pure EVA for a period of time. The morphologies and structures of the residues, revealed by SEM, ascertained that the formed char layers on the composites were denser than that of the LDHs/EVA composites. Mesoporous silica in the material can help smoke suppression. TG-IR data reveal that the incorporation of mesoporous silica-LDHs promoted the release of H2O, and CO2, meanwhile reduced harmful gases release.