To meet the increasingly stringent requirements for the excellent fire safety, low addition, low cost, and good mechanical properties for polycarbonate (PC), a novel aromatic polyimide (API) charring agent was synthesized and used synergistically with hexaphenoxycyclotriphosphazene (HPCTP) to flame‐retardant (FR) PC. The incorporated API and HPCTP improved FR performance and the fracture toughness of the PC, simultaneously. The 4H‐2A passed the UL94 V‐0 rating with a limited oxygen index of 32.5%. Moreover, the heat release rate of the PC was also suppressed significantly by the dense and strengthening carbon layer. The mechanism of synergistic charring effect of API and HPCTP were analyzed: In the initial and developing stages of combustion (below 450°C), the quenching effect and dilution effect of HPCTP played a major role in flame retardancy; and due to the barrier function of the highly graphitized char layer, the combustion process rapidly enters weakening stages (above 450°C) and finally extinguishes. Moreover, it was founded that API improved the antiimpact performance of PC matrix, which offsets the negative effect of HPCTP on the impact performance of PC matrix.

中文翻译：

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聚酰亚胺炭化剂与六苯氧基环三磷腈的协同作用对改善聚碳酸酯的防火性能：高石墨化度可增强炭层

为了满足聚碳酸酯（PC）优异的防火安全性，低添加量，低成本和良好机械性能的日益严格的要求，合成了一种新型芳族聚酰亚胺（API）炭化剂，并与六苯氧基环三磷腈（HPCTP）协同使用以火焰-阻燃（FR）PC。合并的API和HPCTP同时改善了FR性能和PC的断裂韧性。4H-2A通过了UL94 V-0评级，极限氧指数为32.5％。此外，通过致密和强化的碳层，也显着抑制了PC的散热速率。分析了API和HPCTP协同炭化作用的机理：在燃烧的初始阶段和发展阶段（低于450°C），HPCTP的淬灭作用和稀释作用在阻燃性中起主要作用。并且由于高度石墨化的炭层的阻挡功能，燃烧过程迅速进入弱化阶段（高于450°C）并最终熄灭。此外，还发现API改善了PC基质的抗冲击性能，从而抵消了HPCTP对PC基质的冲击性能的负面影响。