Modification of lignin and its application as char agent in intumescent flame-retardant poly(lactic acid)

Authors

  • Rui Zhang,

    1. Department of Material Science and Engineering, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, People's Republic of China
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  • Xifu Xiao,

    1. Department of Material Science and Engineering, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, People's Republic of China
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  • Qilong Tai,

    1. Division of Fire Chemistry, State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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  • Hua Huang,

    1. Department of Material Science and Engineering, College of Chemical Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, People's Republic of China
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  • Yuan Hu

    Corresponding author
    1. Division of Fire Chemistry, State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
    • Division of Fire Chemistry, State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
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Abstract

Urea-modified lignin was prepared according to the Mannich reaction and well characterized by Fourier transform infrared spectrometer, elemental ananlyses, and scanning electron microscopy (SEM). Ammonium polyphosphate (APP) and urea-modified lignin were added into poly(lactic acid) (PLA) as a novel intumescent flame-retardant (IFR) system to improve flame retardancy of PLA. The flammability of IFR–PLA composites was studied using limiting oxygen index, UL-94 vertical burning method and cone calorimeter test, and their thermal stability was evaluated by thermogravimetric analysis. The results showed that the urea-modified lignin combined with APP exhibited much better flame retardancy and thermal stability than that of the combination of virgin lignin and APP. The improvement may be attributed to the better char morphology with more phosphoric char evidenced by SEM and X-ray photoelectron spectroscopy. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

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