Polyurea (PUA) elastomers have gained increasing attention in both defense and civilian fields due to its remarkable mechanical properties and protective capabilities. However, its high flammability significantly limits its application in many fields. It is challenging to achieve high flame retardant rating and maintain high mechanical properties simultaneously. Synergistic combination of different types of flame retardants is essential for this purpose. Herein we report a highly efficient synergistic combination of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and ammonium phosphate (APP) for flame retardance of PUA. BTDA contributes to excellent char-forming in solid phase, and APP contributes to radical scavenging in gaseous phase. By incorporating BTDA and APP as additive flame retardants in PUA, the melt dripping in combustion was entirely suppressed, and V-0 rating in UL-94 test was achieved. The heat release rate and the release of smoke and toxic gases were greatly reduced. Meanwhile, the mechanical properties of PUA were maintained very well. The PUA composites with outstanding flame retardancy and mechanical properties may serve as ideal protective materials in a variety of applications.

中文翻译：

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通过芳香族二酐和聚磷酸铵的协同作用，实现高度阻燃和机械强度高的聚脲


聚脲 （PUA） 弹性体因其卓越的机械性能和保护能力而在国防和民用领域越来越受到关注。然而，它的高可燃性极大地限制了它在许多领域的应用。在实现高阻燃等级和保持高机械性能的同时，这是一项挑战。为此，不同类型阻燃剂的协同组合至关重要。在此，我们报道了 3,3'，4,4'-二苯甲酮四羧酸二酐 （BTDA） 和磷酸铵 （APP） 的高效协同组合，用于 PUA 的阻燃性。BTDA 有助于在固相中实现出色的碳化，而 APP 有助于在气相中自由基清除。通过在 PUA 中加入 BTDA 和 APP 作为添加阻燃剂，完全抑制了燃烧中的熔体滴落，并在 UL-94 测试中获得了 V-0 等级。热释放速率以及烟雾和有毒气体的释放大大降低。同时，PUA 的机械性能保持得非常好。PUA 复合材料具有出色的阻燃性和机械性能，可作为各种应用的理想保护材料。