Functionalized lignin by grafting phosphorus-nitrogen improves the thermal stability and flame retardancy of polypropylene

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• 作者：Youming Yu^a ; Shenyuan Fu^a ; Ping’ ; an Song^a ; ^{pingansong@gmail.com} ; Xiping Luo^b ; Yongming Jin^a ; Fengzhu Lu^a ; Qiang Wu^a ; Jiewang Ye^a
• 关键词：Lignin modification ; Polypropylene ; Thermal stability ; Flame retardancy
• 刊名：Polymer Degradation and Stability
• 出版年：2012
• 期刊代码：85_01413910
• 类别：ms
• 出版时间：April, 2012
• 卷：97
• 期：4
• 页码：541-546
• 文件大小：1358 K

摘要

Improving the thermal stability and flame retardancy of polymers remains a great challenge. Although lignin has been used as a flame retardant for polymers, its flame retardancy effect is usually limited. We, herein, successfully modified alkali lignin by chemically grafting two flame retardant elements, phosphorous and nitrogen, via a three-step reaction. Compared with lignin, modified lignin (PN-lignin) exhibits a much higher char-forming ability with a char of 61.4聽wt%(40.7聽wt%for lignin) at 600聽掳C in N₂. PN-lignin confers a much higher thermal stability and amount of char residue on polypropylene relative to lignin. Moreover, PN-lignin further reduces the heat release rate and slows the combustion process, indicating a better flame retardancy. The continuous and intact char layer mainly contributes to the improved flame retardancy. This strategy not only provides a novel method for flame retarding polymeric materials, but greatly extends the comprehensive utilization of industrial lignin.