【作者】 焦传梅；

【导师】 胡源； 王正洲；

【作者基本信息】 中国科学技术大学 ， 安全技术及工程， 2007， 博士

【摘要】 镁铝水滑石（LDH）结构组成中具有结晶水、羟基等，并且其层板间含有碳酸根，具有较好的阻燃、抑烟功能，是一种高效、无卤、无毒、低烟，环保的新型阻燃剂。本文研究了纳米氢氧化镁（NMH）和纳米水滑石（NLDH）对阻燃乙烯—醋酸乙烯共聚物（EVA）复合材料微观结构、力学性能、燃烧性能及热性能的影响。实验结果表明，NLDH不仅在提高极限氧指数（LOI）、改善垂直燃烧性能和降低热释放速率（HRR）等方面的作用优于NMH，而且在抑烟方面也优于NMH，是一种较好的阻燃抑烟剂。要使复合材料的阻燃性能达到一定要求，NLDH的添加量仍然较大，对材料的力学性能造成了严重的影响；本论文研究了NLDH与微胶囊化红磷（MRP）及白炭黑（SiO₂）在EVA中的阻燃协效作用。结果表明，MRP与NLDH协效阻燃EVA有利于提高材料的LOI和UL-94垂直燃烧级别。热重分析表明，在空气条件下，MRP与NLDH协效阻燃EVA有利于提高复合材料的成炭量。采用Kissinger、Friedman和Flynn-Wall-Ozawa三种方法研究的热解动力学分析表明，材料阻燃性能的提高可能与热解过程表观活化能的增加有关，即存在能量阻隔作用机理；白炭黑（SiO₂）作为EVA／NLDH复合材料的阻燃协效剂有利于改善材料的垂直燃烧性能。研究了用硬脂酸和钛酸酯偶联剂改性的NLDH对EVA／NLDH复合材料的力学性能、燃烧性能及热性能的影响。结果表明，在添加量相同的条件下，硬脂酸改性的NLDH性能要比钛酸酯改性的NLDH性能优良，其主要原因可能与界面和分散性有关；另外，研究了VA含量对EVA／NLDH复合材料的力学性能和燃烧性能的影响。结果表明，VA含量影响NLDH的阻燃效率。这是由于EVA分解释放的醋酸与具有碱性的NLDH发生反应，降低了NLDH的阻燃效率。研究了γ射线辐射交联对EVA／NLDH／MRP复合材料的力学性能、阻燃性能、热稳定性及抗热变形能力的影响。结果表明，γ射线辐射是对EVA／NLDH／MRP复合材料进行交联的一种有效手段。经适度辐射交联的EVA／NLDH／MRP复合材料的力学性能、阻燃性能及抗热变形的能力显著改善，辐射剂量为100kGy时是最佳值；研究了硅烷交联对MH阻燃EVA的影响，结果表明，硅烷交联有利于提高EVA／MH体系的阻燃性能和力学性能。同时阻燃体系中添加硅氧烷有利于提高EVA／MH复合材料的阻燃性能和热稳定性能。采用成核—晶化隔离法制备了Mg／Al-CO₃ LDHs和Mg／Al／Fe-CO₃ LDHs。通过XRD、FT-IR、TG、TEM等分析手段对LDHs化合物进行了表征。采用熔融共混法制备了EVA／LDHs阻燃复合材料，通过LOI、UL-94垂直燃烧试验、TG、锥型量热计等表征手段研究了添加Mg／Al-CO₃ LDHs和Mg／Al／Fe-CO₃ LDHs对EVA树脂的热性能及燃烧性能的影响。实验结果表明，在LDHs中引入适量的Fe³⁺可以提高复合材料的LOI，改善材料燃烧过程中的熔融滴落现象，使阻燃级别提高到V-0级，而且可以降低HRR、延长燃烧时间，使热释放速率最大值出现的时间有所延迟。研究了乙烯—辛烯共聚物（POE）的硅烷接枝交联反应，探讨了硅烷用量、反应时间和反应温度对POE接枝程度的影响；采用热分析手段，研究了硅烷交联POE的热稳定性；同时采用差示扫描量热（DSC）法，对硅烷交联POE进行了非等温结晶动力学分析；结果表明，硅烷用量增加、反应时间延长、反应温度升高均可以增加POE的接枝程度；经过硅烷交联后体系的热稳定性随交联程度的增加而提高。研究了硅烷交联体系的非等温结晶动力学，结果表明，结晶速率随降温速率增加而增大，随POE的交联程度的增加而降低。另外，开展了硅烷交联POE的无卤阻燃研究，探讨了在硅烷交联POE体系中添加MH／SiO₂对该体系的力学性能和阻燃性能的影响。更多还原

【Abstract】 Hydrotalcites （LDHs） are a kind of layered double hydroxides. Due to their special structure characteristics, LDHs are very promising for the application as high efficiency, halogen-free, low-smoke flame retardant additives. The research on the use of nano magnesium hydroxide （NMH） and nano hydrotalcite （NLDH） as flame retardant additive in ethylene vinyl acetate copolymer （EVA） was performed. The microcosmic structure, tensile properties, combustion characteristics and thermal behavior affected by NMH and NLDH of the composites were studied. The results indicate that NLDH is better not only in enhancing the flame retardant properties than that of NMH, but also in smoke suppressant aspect. The loading level of NLDH is very high in order to obtain an adequate level of flame retardant property of EVA. The study of the synergistic effect between NLDH and some other halogen-free retardants, such as microencapsulated red phosphorous （MRP） and fumed silica （SiO₂） in EVA was conducted. The results indicate that there is a great synergistic effect between NLDH and MRP in improving flame retardancy of the composites. Compared with EVA/NLDH composite, the addition of MRP into EVA/NLDH composite could improve the LOI and UL-94 test rating, reduce the peak of heat release rate （PHRR） and enhance the thermal stability. But fumed silica only plays a role in the improving the UL-94 testing rating.The effect of NLDH modified by two kinds of surface modifiers on the tensile properties, combustion properties and thermal behavior of EVA/NLDH composites was studied. It has been found that the tensile properties and thermal stability of EVA/NLDH composite with NLDH modified by stearic acid is better than that of EVA/NLDH composite with NLDH modified by titanate coupling agent. The main reason is due to the surface and distribution. Moreover, the effect of VA content on the tensile properties and combustion properties was also studied. The results indicate that VA content affects the flame retardant efficiency.The EVA/NLDH/MRP composites were crosslinked by ⁶⁰Co irradiation. The effects of gamma irradiation on the properties of the irradiated EVA/NLDH/MRP composites were investigated. The results have shown that gamma irradiation is an effective method of crosslinking for EVA/NLDH/MRP composites. The mechanical properties, flame retardant properties and thermal distortion of the EVA/NLDH/MRP composites were all markedly improved by suitable amount of gamma irradiation doses. The maximal value is achieved when the gamma irradiation dose is 100 kGy; The effect of the silane crosslinking on the flame-retarded EVA by MH was studied. The results indicate that the silane crosslinking can improve the flame-retardant properties and the mechanic properties of the composites of EVA/MH. Meanwhile, the addition of silicone can enhance the flame-retardant properties and thermal stabilities of the EVA/MH composites.Mg/Al-CO₃ LDHs and Mg/Al/Fe-CO₃ LDHs are synthesized by a co-precipitation method and characterized using powder X-ray diffraction （XRD）, Fourier transform infrared （FTIR） spectroscopy, thermogravimetric analysis （TG）. EVA composites flame retarded by LDHs were prepared in a melt process and characterized by LOI, UL-94 testing, TG and cone calorimeter test （CCT）. It has been found that introduction of Fe³⁺ into Mg/Al-CO₃ LDHs can enhance the LOI and UL 94 rating, improve the melt dripping phenomenon, reduce HRR, and prolong the combustion time.The grafting of silane on ethylene-octene copolymer （POE） in presence of DCP in the melt process and the effect of various factors, such as silane content, reaction temperature and time on silane grafting of POE were studied. The TG analysis shows that the thermal stability of the crosslinked POE increases compared to the pure POE resin. The non-isothermal crystallization kinetics of sliane crosslinked POE was studied by differential scanning calorimetry （DSC） at different cooling rate. The results indicate that the crystallization rates decrease with the increase of the crosslinking degree. However, the crosslinked POE is still combustible. Therefore, some research work was done on the halogen-free flame retardation of silane crosslinked POE. The results indicate that fumed silica is not only as the reinforcing filler but also as the synergistic flame retardant additives of MH.更多还原