In situ synthesis of layered double hydroxides-silicon dioxide hybrids and its flame retardancy in EVA composites

Layered double hydroxides-silicon dioxide hybrids (LDH-Si) were in situ synthesized by a co-precipitation method. Flame-retardant, smoke suppression and thermal degradation properties of the LDH-Si in ethylene-vinyl acetate (EVA) composites were studied using cone calorimeter test (CCT), limiting oxygen index (LOI), smoke density test (SDT), and thermogravimetry-Fourier transform infrared spectrometry. The CCT results indicated that the peak heat release rate and peak smoke production rate of the EVA/LDH-Si composite with 2.5mass% SiO2 were decreased by 28.5 and 21.9% compared to EVA/LDH composite, respectively. The LOI results showed that a suitable addition of SiO2 can significantly enhance the LOI values of the EVA composites. It was obtained from SDT that SiO2 could help smoke suppression. The EVA/LDH-Si composites possessed a higher thermal stability than the EVA/LDH composites at high temperatures.