Preparation of silicate modified hydrotalcite and its influence on EVA combustion characteristics and thermal property
To synthesize silicate modified hydrotalcite written as Mg-Al-SiO3, series synthesis methods such as co-precipitation, roasting recovery and ion exchange were tested using Mg(NO3)2·6H2O, Al(NO3)3·9H2O and Na2SiO3·9H2O as raw materials.With crystallinity and purity of product as judgment standard, co-precipitation hydrothermal method at 120°C and crystallization 24.0 h was confirmed and employed to prepare Mg-Al-SiO3 flame retardant. X-ray diffraction spectroscopy (XRD), Field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FTIR) characterized itsmorphology, structure and functional groups. The gravimetric analysis (TG), differential thermal gravimetric (DTG) and limiting oxygen index (LOI) experiments testify that the addition of the prepared Mg-Al-SiO3 hydrotalcite can decrease the thermal stability of ethylene vinyl acetate copolymer (EVA) in low temperature range, but it can obviously reduce the maximummass loss rate and improve residual char and LOI value. It can be found by comparison experiment that Mg-Al-CO3 hydrotalcite shows better flame retardancy than Mg-Al- SiO3.