磷化淀粉的合成及其与聚磷酸铵协效阻燃聚乳酸的性能研究

利用9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)和马来酸酐(MA)对淀粉进行改性得到磷化淀粉(DOPOMASt),通过红外光谱(FTIR)、核磁共振谱(1H-NMR)和X射线光电子能谱(XPS)确定其结构.利用DOPOMASt作为碳源,与聚磷酸铵(APP)复配后通过熔融共混制备了阻燃聚乳酸(PLA)复合材料.采用垂直燃烧(UL-94)、极限氧指数(LOI)、热重分析(TGA)研究DOPOMASt对PLA的阻燃性能和热性能的影响.利用扫描电子显微镜(SEM)观察阻燃剂在PLA中的分散和燃烧后残炭的微观形貌,同时采用TG-IR联用技术对PLA复合材料热降解气相产物进行分析.结果表明,DOPOMASt促进APP在PLA中分散均匀,当DOPOMASt和APP质量比为1∶1,总质量为10%时,LOI达到26.0%且通过UL-94 V0测试.DOPOMASt与APP协效阻燃促进PLA树脂成碳,形成更加致密的炭层并减少可燃气体的产生,赋予PLA良好的阻燃性能.

Synthesis of Phospholipidated Starch and Its Application for Flame-retardant Poly(lactic acid)with Ammonium Polyphosphate

Phospholipidated starch was synthesized according to the reaction between hydroxyl of starch and anhydride prepared by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO)and maleic anhydride(MA),which was characterized by Fourier infrared spectroscopy(FTIR),nuclear magnetic resonance(1 H-NMR),and X-ray photoelectron spectrometry(XPS).Melt-blended with ammonium polyphosphate(APP),the phosphorous-containing starch(DOPOMASt)was used in intumescent flame retardancy of poly(lactic acid)(PLA)as carbon source.The thermal stability and flame retardancy of PLA composites were measured by vertical burning test(UL-94),limiting oxygen index(LOI)and thermogravimetric analysis(TGA).Dispersion of flame retardants in PLA and morphology of char residues after UL-94 test were observed by scanning electron microscopy(SEM).The gases released during thermal degradation of PLA composites were analyzed by TG-IR.The results showed that the uniform distribution of DOPOMASt and APP in PLA matrix was observed.When the mass ratio of DOPOMASt/APP is equal to 1/1,the LOI value of 26.0%and a UL-94 V0 rating were achieved with 10%total flame retardants.Synergistic effect of DOPOMASt and APP resulted in a compact cross-linked char layer and reduction of the retardant-induced smoke release.