A novel bio-flame retardant (PA-B) was prepared based on green materials--banana peel powder (BPP) and phytic acid (PA), then PA-B was used to prepare flame retardant poly(lactic acid) (PLA) composites. The flame retardancy and thermal property of PLA composites were studied. It can be found that the limiting oxygen index (LOI) of PLA composite with 15.0 wt% BPP is 22.1%, showing the heavy dripping during the combustion and failing to reach the vertical burning tests (UL-94) V-0 rating. However, when 15.0 wt% PA-B is added, the LOI is significantly increased to 37.5%, and the composite can reach UL-94 V-0 rating with the dripping problem is obviously reduced. Furthermore, PA-B is helpful to ameliorate the thermal property of PLA composites under the high temperature. The char residue of PLA/PA-B15 is 10.9 wt% at 550.0 °C, showing much higher value than that of PLA/B15 (3.3 wt%) and pure PLA (almost nothing left). From flammability analysis, PA-B not only is a crucial part of promoting the formation of char layer with high quality in the solid phase, which can play a “barrier effect” role to protect the underlying matrix and retard combustion process, but also has the flame retardant effect in the gaseous phase on the basis of PO· free radical. This work provides an efficient way to prepare bio-based flame retardant PLA composites, and also offers a new method to reuse agricultural wastes like banana peel.

The sketch of eco-friendly flame retardant poly(lactic acid) composites

以香蕉皮粉（BPP）和植酸（PA）为绿色原料，制备了新型生物阻燃剂（PA-B），然后用PA-B制备了阻燃性聚乳酸（PLA）。复合材料。研究了PLA复合材料的阻燃性和热性能。可以发现，具有15.0 wt％BPP的PLA复合材料的极限氧指数（LOI）为22.1％，显示出燃烧过程中的大量滴​​落，并且未达到垂直燃烧测试（UL-94）V-0等级。然而，当添加15.0重量％的PA-B时，LOI显着增加至37.5％，并且复合材料可以达到UL-94 V-0等级，并且滴落问题明显减少。此外，PA-B有助于改善高温下PLA复合材料的热性能。PLA / PA-B15的残炭在550.0°C时为10.9 wt％，与PLA / B15（3.3 wt％）和纯PLA（几乎一无所有）相比，显示出更高的价值。从可燃性分析来看，PA-B不仅是促进固相中高质量炭层形成的关键部分，它可以起到“屏障效应”的作用，以保护基础基质并延缓燃烧过程，而且还具有PO·自由基对气相的阻燃作用。这项工作为制备生物基阻燃PLA复合材料提供了一种有效的方法，也为重复利用香蕉皮等农业废弃物提供了一种新方法。它可以起到“阻隔作用”的作用，以保护下面的基体并延迟燃烧过程，还可以基于PO·自由基在气相中起到阻燃作用。这项工作为制备生物基阻燃PLA复合材料提供了一种有效的方法，也为重复利用香蕉皮等农业废弃物提供了一种新方法。它可以起到“阻隔作用”的作用，以保护下面的基体并延迟燃烧过程，但还可以基于PO·自由基在气相中起到阻燃作用。这项工作为制备生物基阻燃PLA复合材料提供了一种有效的方法，也为重复利用香蕉皮等农业废弃物提供了一种新方法。

环保型阻燃聚乳酸复合材料示意图