Benzoxazine monomers of traditional bisphenol‐A benzoxazine (BA‐a) and bisphenol‐A benzoxazine containing trialkoxysilane (BA‐a‐Si) were synthesized and incorporated into polyoxymethylene/ammonium polyphosphate/melamine (POM/APP/ME) to improve the fire retardancy of POM. The flame retardation, thermal, and mechanical properties of POM composites were evaluated by cone calorimeter, limiting oxygen index (LOI), and the Underwriters Laboratories‐94 (UL‐94) vertical burning tests, as well as thermogravimetric analysis and mechanical tests. Addition of BA‐a‐Si (2 wt%) into POM could simultaneously improve its flame retardancy (UL‐94 vertical burning rating to V‐0 rating and LOI value reached 52.1%) and notched impact strength (increased by 33.3% and 100.0% compared with that of POM/APP/ME and POM/APP/ME/BA‐a composites). Notably, compared with POM/APP/ME composite, the smoke productions of both the composites with benzoxazines were significantly suppressed. In contrast, the peak heat release rate and total heat release of composite with 2 wt% BA‐a‐Si were 33.3% and 32.9% lower than those of composite with 2 wt% BA‐a, which were closely related to the formation of high quality and quantity of charred residue. In summary, benzoxazine, especially siloxane‐containing benzoxazine, plays an effective role in flame retarding POM acting as charring agent and synergistic flame retardant.

中文翻译：

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膨胀型聚甲醛中苯并恶嗪增效剂的阻燃作用及机理

合成了传统双酚A苯并恶嗪（BA-a）的苯并恶嗪单体和含三烷氧基硅烷（BA-a-Si）的双酚A苯并恶嗪并将其掺入聚甲醛/聚磷酸铵/三聚氰胺（POM / APP / ME）中以提高阻燃性的POM。通过锥形量热仪，极限氧指数（LOI）和Underwriters Laboratories‐94（UL‐94）垂直燃烧测试以及热重分析和力学测试对POM复合材料的阻燃性，热性能和机械性能进行了评估。在POM中添加BA-a-Si（2 wt％）可以同时提高其阻燃性（UL-94垂直燃烧等级至V-0等级，LOI值达到52.1％）和缺口冲击强度（分别提高33.3％和100.0）与POM / APP / ME和POM / APP / ME / BA-a复合材料相比）。值得注意的是 与POM / APP / ME复合材料相比，两种含苯并恶嗪的复合材料的烟雾产生均得到显着抑制。相比之下，BA-a-Si 2 wt％的复合材料的峰值放热率和总放热比BA-a 2 wt％的复合材料的峰值放热率和总放热分别低33.3％和32.9％，这与B-a-Si的形成密切相关。烧焦残渣的质量和数量都很高。总而言之，苯并恶嗪，尤其是含硅氧烷的苯并恶嗪，在作为炭化剂和协同阻燃剂的阻燃POM中起着有效的作用。这与高品质和高数量的焦化残渣的形成密切相关。总而言之，苯并恶嗪，尤其是含硅氧烷的苯并恶嗪，在作为炭化剂和协同阻燃剂的阻燃POM中起着有效的作用。这与高品质和高数量的焦化残渣的形成密切相关。总而言之，苯并恶嗪，尤其是含硅氧烷的苯并恶嗪，在作为炭化剂和协同阻燃剂的阻燃POM中起着有效的作用。