An efficient zinc borate/silica composite flame retardant (CFR), with accumulating nano-silica (SiO₂) on the surface of grown zinc borate (ZnB) flakes to form a core/shell structure, was synthesized via a facile precipitation route. When mixed with methyl vinyl silicone rubber (VMQ), this combined structure of CFR brought advantages in both flame retardancy and mechanical properties. During a process of combustion, these CFR particles migrated and assembled on the surface of combustion zone, increasing the local concentration and generating a tight and intumescent surface char layer even at a lower loading amount. In comparison with the VMQ/physical mixture (PM, with the same proportion of SiO₂ and ZnB), the EVA/CFR formulation passed a UL94 V–0 rating and got a LOI value of 29.5, when used as an alternative of SiO₂ filler. Meanwhile, CFR played an effective role in inhibiting the spread of fire; VMQ/CFR showed a fire growth index (FGI) of 0.56 much lower than 0.92 of VMQ/PM. In this case, the heat release rate (HRR), total heat released (THR) and smoke production rate (SPR) were considerably reduced. Moreover, the mechanical properties of VMQ/CFR blends, including both tensile strength (TS) and elongation at break (EAB), were significantly enhanced.

通过一种便捷的沉淀途径，合成了一种高效的硼酸锌/二氧化硅复合阻燃剂（CFR），其在生长的硼酸锌（ZnB）薄片表面形成纳米二氧化硅（SiO ₂），从而形成核/壳结构。当与甲基乙烯基硅橡胶（VMQ）混合时，CFR的这种组合结构在阻燃性和机械性能方面均具有优势。在燃烧过程中，这些CFR粒子迁移并聚集在燃烧区的表面上，从而增加了局部浓度，即使在较低的负载量下也产生了紧密而膨胀的表面炭层。与VMQ /物理混合物（PM，相同比例的SiO ₂和ZnB），当用作SiO ₂填料的替代品时，EVA / CFR配方通过了UL94 V-0等级，LOI值为29.5 。同时，病死率在抑制火势蔓延方面发挥了有效作用。VMQ / CFR的火势增长指数（FGI）为0.56，远低于VMQ / PM的0.92。在这种情况下，放热率（HRR），总放热（THR）和烟雾产生率（SPR）大大降低。此外，VMQ / CFR共混物的机械性能（包括拉伸强度（TS）和断裂伸长率（EAB））均得到显着提高。