含P、N、S 的DOPO基阻燃剂制备及阻燃环氧树脂性能

P, N, S containing DOPO-based flame retardants and their flame-retardant performance in epoxy resin

摘要:

以生物基糠醛、2-氨基-1,3,4-噻二唑和9,10-二氢-9-氧代-10-磷杂菲-10-氧化物（DOPO）为原料，合成了含P、N、S的阻燃剂（6-(1,3,4-噻二唑-2-氨基)(呋喃-2-甲基)二苯[b,e][1,2]氧萘膦吡啶六氧化物，MBFAP） ，将其与环氧树脂（EP）共混制备阻燃环氧树脂（EP/MBFAP），采用FTIR和NMR对MBFAP结构进行表征，基于TGA、DSC、TG-FTIR、DMA、垂直燃烧测试仪、锥形量热分析仪、SEM、XPS、Raman、电子万能试验机、简支梁冲击试验机、UV-Vis等测试，考察不同MBFAP添加量 （阻燃EP总质量的质量分数，下同）对EP/MBFAP的固化行为、阻燃效果、热稳定性、燃烧特性、力学性能及透明度的影响，并推测MBFAP阻燃EP的可能机理。结果表明，MBFAP的添加显著降低了EP/MBFAP的最大分解速率，促进EP的早期分解。MBFAP添加量为4%的EP/MBFAP-4在UL-94标准测试（垂直燃烧）达到V-0级，氧指数为33.5%；与纯EP相比，EP/MBFAP-4的总烟气释放量、峰值热释放率和总热释放量分别减少了12.7%、24.9%和19.2%；残炭和热解挥发性气体测试表明，MBFAP在气相和凝聚相中都起到阻燃作用。EP/MBFAP-4的透光率（70.75%）相比纯EP（87.17%）有一定程度降低；EP/MBFAP-4的拉伸强度（72.26 MPa）、弯曲强度（74.19 MPa）、冲击强度（42.2 kJ/m2）较纯EP分别提高了14.97%、12.51%和28.26%，但断裂伸长率（5.1%）较纯EP（6.5%）略有下降。

Abstract:

A novel phosphorus, nitrogen, sulfur containing flame retardant (6-(((1,3,4-thiadiazol-2-yl)amino)(furan-2-yl)methyl)dibenzo[c,e][1,2]oxaphosphinine 6-oxide, MBFAP) was synthesized from bio-based furfural, 2-amino-1,3,4-thiadiazole, and 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide (DOPO). Flame retardant epoxy resin (EP/MBFAP) was then prepared by blending MBFAP with epoxy resin (EP). The structure of MBFAP was confirmed by FTIR and NMR. The curing behavior, flame retardant performance, thermal stability, combustion characteristics, mechanical properties, and transparency of EP/MBFAP with different MBFAP loadings (mass fraction, based on the total mass of flame-retardant epoxy resin, and the same applies hereafter)were investigated using TGA, DSC, TG-FTIR, DMA, vertical burning test, cone calorimeter, SEM, XPS, Raman, universal testing machine, Charpy impact tester, and UV-Vis spectroscopy. Finally, the possible flame retardant mechanism of MBFAP in EP was proposed. The results showed that the addition of MBFAP significantly reduced the maximum decomposition rate of EP/MBFAP and promoted the early decomposition of EP. The EP/MBFAP-4 with 4 wt% MBFAP loading achieved a V-0 rating in the UL-94 standard test (vertical burning) and an oxygen index of 33.5%. Compared to pure EP, the total smoke release, peak heat release rate, and total heat release of EP/MBFAP-4 were reduced by 12.7%, 24.9%, and 19.2%, respectively. Char residue and pyrolysis volatile gas tests indicated that MBFAP played a flame retardant role in both the gas phase and condensed phase. The transmittance of EP/MBFAP-4 (70.75%) was slightly reduced compared to that of pure EP (87.17%). The tensile strength (72.26 MPa), flexural strength (74.19 MPa), and impact strength (42.2 kJ/m2) of EP/MBFAP-4 were increased by 14.97%, 12.51%, and 28.26%, respectively, compared to pure EP, while the elongation at break (5.1%) was slightly decreased compared to pure EP (6.5%).