Dual Modification of Magnesium Hydroxide: In Situ Growth of Neodymium Hydroxide and Organic Functionalization for Improving Fire Safety and Physical Properties of EVA Composites

To address the intrinsic flammability of ethylene-vinyl acetate copolymer (EVA) and the deterioration of mechanical properties caused by high loadings of traditional flame retardants, a novel organic–inorganic hybrid flame retardant (MH@NdH@Si) was prepared via in situ growth of Nd(OH)3 and KH570 modification on the surface of Mg(OH)2 hexagonal sheets, which was applied to the EVA matrix. The results demonstrate that MH@NdH@Si can significantly enhance fire safety and physical properties of EVA composites. Compared with pure EVA, EVA/MH@NdH@Si achieves V-0 rating in the UL-94 test and limiting oxygen index as high as 36%. The peak heat release rate of EVA/MH@NdH@Si is reduced by 82.8%, which drastically mitigates the fire risk induced by the EVA composites. In addition, the peak production rates of CO and CO2 of the EVA/MH@NdH@Si composite are much lower than those of pure EVA, indicating a remarkable inhibitory effect of MH@NdH@Si on the release of toxic gases. The elongation at break of EVA/MH@NdH@Si is increased to 179%, improving by 105.7% compared to that of EVA/MH, which effectively alleviates the mechanical degradation of composites caused by Mg(OH)2 fillers. In conclusion, the organic–inorganic hybrid flame-retardant MH@NdH@Si constructed in this study can realize excellent flame retardant and smoke suppression while improving the physical properties of composites, thus providing a novel strategy for the development of high-performance flame-retardant EVA composites with balanced comprehensive properties.