In order to improve the flame retardant of polylactide (PLA), the synergistic effect of graphitic carbon nitride (g‐C₃N₄) with commercial‐available flame retardants melamine pyrophosphate (MPP) and 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) was investigated. The PLA composites containing 5 wt% g‐C₃N₄ and 10 wt% DOPO had a highest limited oxygen index (LOI) value of 29.5% and reached the V‐0 rating of UL‐94 test. The cone calorimeter tests exhibited that DOPO had a better synergistic effect with g‐C₃N₄ than MPP to improve flame retardancy of PLA. The peak heat release rate (pHRR) and total heat release (THR) of PLA composites containing 10 wt% DOPO could be reduced by 25.2% and 23.6%, respectively, as compared with those of pure PLA. The presence of rich phosphorus element and aromatic groups in DOPO contributed to obtain continuous compact char layer and increase the graphitization level of char residues, thereby, resulting in improving the flame retardancy of PLA together with g‐C₃N₄. In addition, the incorporation of DOPO can serve as a plasticizer to reduce the complex viscosity, improving the processability of PLA composites.

中文翻译：

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阻燃剂与石墨氮化碳的协同作用对聚丙交酯复合材料阻燃性的影响

为了提高聚丙交酯（PLA）的阻燃性，石墨氮化碳（g C ₃ N ₄）与市售阻燃剂三聚氰胺焦磷酸酯（MPP）和9,10-二氢-9-乙二胺的协同作用研究了10-磷菲-10-氧化物（DOPO）。含有5 wt％g C ₃ N ₄和10 wt％DOPO的PLA复合材料的最高极限氧指数（LOI）值为29.5％，达到UL 94测试的V-0等级。锥形量热仪测试表明，DOPO与g ‐ C ₃ N ₄具有更好的协同作用比MPP改善PLA的阻燃性。与纯PLA相比，含10 wt％DOPO的PLA复合材料的峰值放热率（pHRR）和总放热（THR）可以分别降低25.2％和23.6％。DOPO中富磷元素和芳族基团的存在有助于获得连续的致密焦炭层，并提高了炭渣的石墨化水平，从而提高了PLA与g ‐ C ₃ N ₄的阻燃性。另外，掺入DOPO可以用作增塑剂以降低复数粘度，从而改善PLA复合材料的可加工性。