Synergistic Effects of Modified Hydrotalcite on Improving the Fire Resistance of Ethylene Vinyl Acetate Containing Intumescent Flame Retardants

The NH2SO3-1 intercalated MgAl-LDH (SA-LDH) was prepared and then introduced into ethylene vinyl acetate (EVA) in association with intumescent flame retardants (IFR) in order to improve the flame retardancy of the composite. The structure and thermal stability of SA-LDH was characterized by Fourier transform infrared, X-ray diffraction, transmission electron microscopy, and thermogravimetry analysis. The flame retardancy of EVA composite was evaluated by limiting oxygen index (LOI), vertical burning UL-94, and cone calorimeter tests. The presence of only 1 wt% SA-LDH could increase the LOI of EVA/IFR composite from 24.8 to 26.9, and significantly reduced the peak HRR value. The morphology of char after combustion was observed by scanning electron microscope, and it revealed that the presence of SA-LDH was beneficial to form compact char structure. It was proposed that there existed synergism between SA-LDH and IFR in improving the fire performance of EVA composite. (C) 2016 Society of Plastics Engineers