Rubber nanocomposite foams based on 60/40 ethylene vinyl acetate (EVA)/natural rubber (NR) were melt-mixed with flame retardant silicon dioxide (SiO₂) (20 parts per hundred rubber, phr), and foamed by compression molding process. In this study, the effect of mixing phenomena of SiO₂ through two different compounding techniques such as direct mixing (DM) and phase selective mixing (PSM) methods on structure, thermal stability, combustility and flame retardancy of EVA/NR blend nanocomposite foams were investigated. DM method is a melt mixing of EVA, NR, layered silicate and SiO₂, followed by foaming. PSM is a new method based on pre-mixing EVA with SiO₂, then melt mixing of EVA/SiO₂ masterbatch with NR and layered silicate, and finally foaming. Based on TEM technique, it was found that the SiO₂ was exclusively located in dispersed NR phase for the sample prepared by DM method, and the SiO₂ was preferably dispersed in continuous EVA matrix when PSM method was employed. However, the different mixing methods did not significantly alter their cellular structures. The thermal stability and char residue content of foamed samples with SiO₂ increased obviously when compared with those of corresponding foams without SiO₂. The results based on limiting oxygen index (LOI) test and oxygen bomb calorimetry indicated that the foams combined with SiO₂ had better combustion resistance and flame retardancy due to barrier effect of thermally stable silicon-based char layer. Further, the SiO₂ filled foamed system obtained from the PSM method showed a higher degree of improvement in thermal stability, combustion resistance and flame retardancy than that of DM method because the homogeneous dispersion of SiO₂ in EVA matrix rather than the selective dispersion in NR phase. This resulted in the continuity of flame retardant EVA/SiO₂ phase in the 60/40 EVA/NR nanocomposite foams, which exerted more efficient fire barrier of the silicon-based char layer.

将基于60/40乙烯乙酸乙烯酯（EVA）/天然橡胶（NR）的橡胶纳米复合泡沫材料与阻燃二氧化硅（SiO ₂）（每100份橡胶20份，phr）熔融混合，并通过压缩成型工艺发泡。在这项研究中，SiO ₂通过两种不同的混合技术（例如直接混合（DM）和相选择混合（PSM）方法）的混合现象对EVA / NR混合纳米复合泡沫的结构，热稳定性，可燃性和阻燃性的影响是调查。DM法是将EVA，NR，层状硅酸盐和SiO ₂熔融混合，然后发泡。PSM是一种新方法，它是将EVA与SiO ₂预混合，然后将EVA / SiO ₂熔融混合。用NR和层状硅酸盐制成母料，最后发泡。基于TEM技术，发现对于通过DM方法制备的样品，SiO ₂仅位于分散的NR相中，并且当采用PSM方法时，优选将SiO ₂分散在连续的EVA基质中。但是，不同的混合方法并未显着改变其细胞结构。与相应的不含SiO _2的泡沫相比，含SiO ₂的泡沫样品的热稳定性和残炭含量明显增加。基于极限氧指数（LOI）测试和氧弹量热法的结果表明，泡沫与SiO ₂结合由于具有热稳定性的硅基炭层的阻挡作用，因此具有更好的阻燃性和阻燃性。此外，由PSM方法获得的填充有SiO _2的泡沫体系与DM方法相比，在热稳定性，阻燃性和阻燃性方面显示出更高的改善程度，这是因为SiO ₂在EVA基体中的均匀分散而不是在NR中的选择性分散。相。这导致了60/40 EVA / NR纳米复合泡沫材料中阻燃性EVA / SiO ₂相的连续性，从而为硅基炭层提供了更有效的防火屏障。