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 2.5 mass% SiO 2 were decreased by 28.5 and 21.9% compared to EVA/LDH composite, respectively. The LOI results showed that a suitable addition of SiO 2 can significantly enhance the LOI values of the EVA composites. It was obtained from SDT that SiO 2 could help smoke suppression. The EVA/LDH-Si composites possessed a higher thermal stability than the EVA/LDH composites at high temperatures.