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Open AccessArticle

Preparation of γ-Divinyl-3-Aminopropyltriethoxysilane Modified Lignin and Its Application in Flame Retardant Poly(lactic acid)

by Yan Song 1,2, Xu Zong 1, Nan Wang 1, Ning Yan 3, Xueying Shan 4 and Jinchun Li 1,2,*
1
Faculty of Materials Science & Engineering, Changzhou University, Changzhou 213164, Jiangsu, China
2
Jiangsu Key Laboratory of Environmentally Friendly Polymer Materials, Changzhou University, Changzhou 213164, Jiangsu, China
3
Faculty of Forestry, University of Toronto, 33 Willcocks Street, Toronto, ON M5S 3B3, Canada
4
School of Environmental and Safety Engineering, Changzhou University, Changzhou 213164, Jiangsu, China
*
Author to whom correspondence should be addressed.
Materials 2018, 11(9), 1505; https://doi.org/10.3390/ma11091505
Received: 15 July 2018 / Revised: 11 August 2018 / Accepted: 15 August 2018 / Published: 22 August 2018
(This article belongs to the Special Issue Green Composites: Preparation, Properties, and Applications)
Lignin can be a candidate as a charring agent applied in halogen-free flame retardant polymers, and incorporation of silicon and nitrogen elements in lignin can benefit to enhancing its thermal stability and charring ability. In the present work, wheat straw alkali lignin (Lig) was modified to incorporate silicon and nitrogen elements by γ-divinyl-3-aminopropyltriethoxysilane, and the modified lignin (CLig) was combined with ammonium polyphosphate (APP) as intumescent flame retardant to be applied in poly(Lactic acid) (PLA). The flame retardancy, combustion behavior and thermal stability of PLA composites were studied by the limited oxygen index (LOI), vertical burning testing (UL-94), cone calorimetry testing (CCT) and thermogravimetric analysis (TGA), respectively. The results showed a significant synergistic effect between CLig and APP in flame retarded PLA (PLA/APP/CLig) occured, and the PLA/APP/CLig had better flame retardancy. CCT data analysis revealed that CLig and APP largely reduced the peak heat release rate (PHRR) and total heat release rate (THR) of PLA, indicating their effectiveness in decreasing the combustion of PLA. TGA results exhibited that APP and CLig improved the thermal stability of PLA at high temperature. The analysis of morphology and structure of residual char indicated that a continuous, compact and intumescent char layer on the material surface formed during firing, and had higher graphitization degree. Mechanical properties data showed that PLA/APP/CLig had higher tensile strength as well as elongation at break. View Full-Text
Keywords: wheat straw soda lignin; silicon and nitrogen elements; poly(lactic acid); thermal stability; combustion behavior wheat straw soda lignin; silicon and nitrogen elements; poly(lactic acid); thermal stability; combustion behavior
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MDPI and ACS Style

Song, Y.; Zong, X.; Wang, N.; Yan, N.; Shan, X.; Li, J. Preparation of γ-Divinyl-3-Aminopropyltriethoxysilane Modified Lignin and Its Application in Flame Retardant Poly(lactic acid). Materials 2018, 11, 1505.

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