Zhang Y M, Zhao Q, Li L, Yan R, Zhang J, Duan J C, Liu B J, Sun Z Y, Zhang M Y, Hu W, Zhang N N
College of Chemical Engineering, Changchun University of Technology 2055 Yan'an Street Changchun 130012 P. R. China
School of Life Science and Technology, Harbin Institute of Technology Harbin 150080 P. R. China.
RSC Adv. 2018 Sep 18;8(56):32252-32261. doi: 10.1039/c8ra05598j. eCollection 2018 Sep 12.
In this work, new lignin-based flame retardant LHDs were successfully synthesized through the reaction between lignin, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and hexamethylene diisocyanate (HDI). The chemical structure of LHD was characterized by FTIR, H NMR, P NMR. The thermal stability of LHD was studied by TGA. The results showed that the residual carbon content of L15HD (15% of lignin in LHD) at 600 °C reached 16.55%, indicating that this prepared flame retardant can be a type of good char forming agent. LHDs were then applied to prepare flame-retardant lignin-based polyurethane (FLPU). Lignin-based polyurethane (LPU) was synthesized by the reaction between lignin, polyethylene glycol 200 (PEG 200) and hexamethylene diisocyanate (HDI). The limiting oxygen index (LOI) value of the FLPU reached 30.2% when the addition content of L15HD (15% lignin in LHD) in LPU (20% lignin in LPU) was 25%, exhibiting excellent flame-retardant properties. Scanning electron microscopy (SEM) analysis of the FLPU char residual showed that there was a continuous dense outer carbon layer on the residue surface, and the inner carbon layer had many expansion bubbles, indicating the LHDs have an excellent flame retardant effect for PU. In addition, FLPU presented better hardness and adhesion than PU. The hardness of FLPU (lignin content in LPU was 20%, and added content of L15HD in LPU was 25%) reached 4H, and its adhesion was 0. These excellent properties illustrated that the LHDs are ideal flame retardants and reinforcing agents for LPU because of the co-curing and strong interface between LHD and LPU.
在本工作中，通过木质素、9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物（DOPO）和六亚甲基二异氰酸酯（HDI）之间的反应成功合成了新型木质素基阻燃剂LHDs。通过傅里叶变换红外光谱（FTIR）、氢核磁共振（H NMR）、磷核磁共振（P NMR）对LHD的化学结构进行了表征。通过热重分析（TGA）研究了LHD的热稳定性。结果表明，L15HD（LHD中木质素含量为15%）在600℃时的残炭率达到16.55%，表明所制备的这种阻燃剂可成为一种良好的成炭剂。然后将LHDs应用于制备阻燃木质素基聚氨酯（FLPU）。通过木质素、聚乙二醇200（PEG 200）和六亚甲基二异氰酸酯（HDI）之间的反应合成了木质素基聚氨酯（LPU）。当LPU（LPU中木质素含量为20%）中L15HD（LHD中木质素含量为15%）的添加量为25%时，FLPU的极限氧指数（LOI）值达到30.2%，表现出优异的阻燃性能。对FLPU残炭的扫描电子显微镜（SEM）分析表明，残炭表面有连续致密的外层碳层，内层碳层有许多膨胀气泡，表明LHDs对PU具有优异的阻燃效果。此外，FLPU比PU具有更好的硬度和附着力。FLPU（LPU中木质素含量为20%，LPU中L15HD的添加量为25%）的硬度达到4H，附着力为0级。这些优异性能表明，由于LHD与LPU之间的共固化作用和强界面作用，LHDs是LPU理想的阻燃剂和增强剂。
