二乙基次膦酸铝和OMMT在PLA中协同阻燃作用研究

Synergistic Effect Between Aluminum Hypophosphite and OMMT in Flame-Retarded PLA

采用熔融共混工艺制备了一系列聚乳酸(PLA)/二乙基次膦酸铝(AHP)和PLA/AHP/有机蒙脱土(OMMT)复合材料,并通过热失重分析、极限氧指数、垂直燃烧和锥形量热仪测试研究了AHP和OMMT对PLA复合材料热稳定性和阻燃性能的影响,探讨了AHP和OMMT协同阻燃的作用机理。结果表明,相比于PLA/AHP复合材料,PLA/AHP/OMMT复合材料表现出更优异的热稳定性和阻燃性能,材料的最大热分解温度提高了约3℃,而且能够通过垂直燃烧UL 94 V–0级别测试,同时材料的热释放速率峰值、平均热释放速率、平均质量损失速率等都出现显著降低,这证实AHP和OMMT在PLA基体中具有明显的协同阻燃效果。扫描电子显微镜观察材料燃烧后残炭的微观形貌发现,与PLA/AHP相比,PLA/AHP/OMMT的炭层更加连续、致密,红外结果显示该炭层中有"类陶瓷"结构生成,起到了促进成炭及稳定炭层结构的作用,这是AHP和OMMT发挥良好协同阻燃效果的原因。

A series of PLA / aluminum diethylphosphite （AHP） composites and PLA / AHP / organic montmorillonite （OMMT） nanocomposites were prepared by melt blending method. Synergistic effects between AHP and OMMT on thermal behavior and combustion properties in PLA matrix were investigated by using thermogravimetric analysis, limiting oxygen index, vertical burning test（UL94）, and cone calorimeter test. Furthermore, the synergistic flame retardant mechanism was explored. The experimental results show that PLA / AHP / OMMT nanocomposite performed more excellent thermal stability and flame retardancy, compared with those of PLA/AHP. TGA results show that the Tmax, of PLA/AHP/OMMT composite was increased by 3 ℃. The results of cone calorimeter test reveal that the heat release rate, average heat release rate, and average mass lost rate decrease markedly. In the vertical test, PLA / AHP / OMMT composite can pass UL94 V-0 level. These results indicate that a distinct synergistic effect between AHP and OMMT in PLA matrix during combustion. SEM micrograph showes that the residual char after cone calorimeter test of PLA/AHP/OMMT composite displays a continuous and compact morphology with a ＂ceramic- like＂ structure. Because of this, PLA / AHP / OMMT nanocomposites exhibits a better flame retardant performance than PLA / AHP composites.