【作者】 王立春；

【导师】 江平开；

【作者基本信息】 上海交通大学 ， 材料学， 2011， 博士

【摘要】 随着高分子材料的不断蓬勃发展,由此带来的火灾隐患和火灾危害成为人们关注的重要问题。当前,对高性能、高效、环境友好聚合物阻燃材料的要求不断提高,阻燃评价方法不断完善和更加科学,世界各国阻燃法规日趋严格,特别是欧盟两项指令“废弃电子电器设备指令"（West Electrical and Electronic Equipment Directive,WEEE）（2003年3月生效）及“电子电器设备中禁用有害物质指令”（Restriction of Hazardous Substances Directive,RoHS）的颁布,使得传统卤素等阻燃体系受到严峻挑战,研究和开发新型高效的无卤阻燃体系显得非常迫切和必要。聚烯烃材料在电线电缆领域被广泛使用。EVA树脂是聚烯烃材料家族中的重要成员之一,它的氧指数较低（< 19%）,燃烧时热释放速率较大,并伴有熔融低落和大量烟雾,因此必须进行阻燃改性。本论文选择具有较高VA含量（50%）的EVA为基体树脂,采用过氧化物DCP进行交联;首先通过三氯氧磷（POCl₃）与季戊四醇（PER）脱氯化氢的反应合成含磷阻燃剂中间体—双官能团化合物螺环季戊四醇双磷酸酯二酰氯（SPDPC）,然后将SPDPC与DOPO结合起来合成出两种不同分子结构的新型含磷阻燃剂（SPDH和SPDV）,将SPDH和SPDV分别应用于EVA的阻燃,研究其阻燃机理;采用过氧化物交联方法,考察氢氧化铝、氢氧化镁无卤阻燃EVA复合材料的阻燃、力学、电学和热老化等性能,并将合成的含磷含硅阻燃剂SPDV用于EVA/MDH复合材料的阻燃优化研究;同时,研究SPDV改性MWCNTs和OMMT阻燃交联EVA基复合材料的阻燃性能,深入分析其阻燃机理;分别采用CaCO₃、NG、EG对EVA/APP/PER/ZB阻燃交联复合材料进行阻燃优化,研究石墨膨胀及氧化前后对EVA基交联复合材料阻燃性能的影响,分析材料成炭性与阻燃性能的关系,研究和探讨其阻燃机理。研究无机填充EVA基复合材料的导热与阻燃性能的关系。⒈新型含磷阻燃剂（SPDH和SPDV）的合成及表征:从分子设计和合成出发,采用化学反应将几种阻燃官能团结合到单分子阻燃剂当中;以三氯氧磷（POCl₃）、季戊四醇（PER）、9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物（DOPO）、对苯醌（HQ）和乙烯基甲基二甲氧基硅烷（VMDMS）为原料,合成出含磷阻燃剂SPDH和含磷含硅阻燃剂SPDV,通过FTIR、NMR、GPC、TGA等测试和分析对两类阻燃剂中间体和终产物进行结构表征和热性能分析。TGA测试结果表明:阻燃剂SPDH和SPDV均具有良好的成炭性,相比较而言在空气中SPDV的炭渣热稳定性更高,温度达800℃时的残炭量仍为44.6%,这是由于SPDV在受热氧作用下可以形成硅氧硅的交联结构,从而提高了其残炭高温下的热稳定性。⒉SPDH、SPDV阻燃交联EVA基复合材料的研究将合成的两种阻燃剂SPDH和SPDV分别应用于EVA的阻燃改性,采用熔融共混的方法制备无卤阻燃交联EVA/SPDH和EVA/SPDV复合材料,研究结果表明:阻燃剂SPDH和SPDV的加入都降低了EVA的PHRR、THR、EHC和MLR,提高了其FPI、燃烧成炭率和LOI,当阻燃剂SPDV添加量达20phr时,其UL-94垂直燃烧可达V-2级,研究表明EVA/SPDH和EVA/SPDV复合材料的阻燃性均得到明显改善;SPDH和SPDV的加入降低了材料的初始热分解温度,点燃时间稍有缩短;EVA/SPDH阻燃交联复合材料的生烟速率和总生烟量均有所增加,而阻燃剂SPDV的加入使得材料的总生烟量有所降低,EVA/SPDV复合材料的残炭量提高更明显,这与含硅化合物的引入提高了炭层的热稳定性并促进成炭有关。通过SEM观察燃烧残炭,可以发现EVA/SPDH复合材料的炭渣出现一些小的孔洞结构,而EVA/SPDV阻燃交联复合材料的炭渣相对前者较为致密,EDS测试结果发现其炭渣外表面硅含量较内部稍高,表明在燃烧时含硅化合物会向炭层表面迁移,这提高了炭层的热稳定性。⒊纳米阻燃剂（MWCNTs、OMMT）阻燃交联EVA基复合材料的研究采用合成的阻燃剂SPDV对MWCNTs进行有机化改性得到MWCNTs-g-SPDV,分别采用FTIR、NMR、TEM和TGA对其结构和热性能进行表征;将MWCNTs和MWCNTs-g-SPDV分别应用于EVA的阻燃,研究结果表明:EVA基阻燃交联复合材料的热稳定性得到改善,同时其PHRR、AHRR均明显降低,TTI、FPI和燃烧残渣均明显增加,表明EVA的阻燃性明显改善;与未改性的MWCNTs相比较,改性后的MWCNTs-g-SPDV对EVA阻燃性的提高更明显,这与其在EVA基体中分散性的提高及其引入的阻燃剂具有促进成炭作用有关。另一方面,将MMT和OMMT分别应用于EVA的阻燃,采用XRD、TEM表征EVA/MMT和EVA/OMMT复合材料的微观结构;研究结果表明:EVA/OMMT插层复合材料的阻燃性得到明显改善,而MMT的加入对阻燃性的改善很小,这是由于OMMT与EVA基体形成插层复合结构,燃烧过程中蒙脱土的无机片层会向材料表面迁移并形成类似“迷宫”的屏障结构,从而起到隔热隔氧的作用,并促进成炭,从而有效提高阻燃性能;而燃烧时OMMT的迁移运动能力是影响成炭性和阻隔作用的重要因素。⒋无机金属氢氧化物（ATH、MDH）阻燃交联EVA基复合材料的性能及其阻燃优化研究分别采用乙烯基甲基二甲氧基硅烷（VMDMS）改性的ATH和氨基硅烷改性的MDH为阻燃剂,DCP为交联剂,DDA为防老剂组成的不同配方,考察其阻燃、力学、电学、热老化和流变性能,研究结果表明:EVA/ATH、EVA/MDH复合材料的阻燃性均明显提高,拉伸强度和断裂伸长率有所降低,击穿强度和体积电阻率略有下降,但仍保持了较高的水平,可以满足无卤阻燃电缆护套材料的使用要求;当DDA的添加量由0.5phr增加到2.5phr时,优化的EVA/MDH复合材料耐温等级由原来105℃提高到125℃。同时,将合成的阻燃剂SPDV对EVA/MDH复合材料进行阻燃优化,研究结果表明:EVA/MDH复合材料的阻燃性进一步提高,UL-94垂直燃烧可达V-0级,MDH和SPDV并用具有明显的膨胀阻燃现象,具有协同阻燃效应;无机阻燃剂MDH在燃烧过程中可以抵抗热辐照和火焰作用引起的样品变形及熔滴,同时MDH和SPDV并用发生膨胀阻燃作用,形成的炭层具有更高的强度,可以更有效的起到屏蔽阻隔和发挥磷/硅的阻燃作用,由此提高阻燃效率。⒌膨胀阻燃体系阻燃交联EVA基复合材料的阻燃性能及其机理研究分别采用CaCO₃、NG、EG对EVA/APP/PER/ZB阻燃交联复合材料进行阻燃优化,研究结果发现:CaCO₃、NG、EG的加入均进一步降低了复合材料的PHRR、THR、SPR,增加了FPI、TTI及燃烧残渣,表明其阻燃性和抑烟性均进一步改善,表现出明显的阻燃协同效应。分析和研究其炭渣结构发现:CaCO₃、NG、EG的加入均明显提高了炭渣的热稳定性和强度,这是其阻燃性进一步改善的重要原因。进一步研究NG、EG和GO阻燃交联EVA基复合材料的阻燃性,研究结果发现:EVA/EG复合材料的阻燃性和抑烟性提高最明显,而EVA/NG、EVA/GO复合材料的阻燃性提高幅度相对较低,EVA/GO复合材料的抑烟性提高最小。原因是由于EG燃烧时发生巨大膨胀,形成许多具有层间空隙的石墨保护层,有效延缓了热、氧的传递,降低了燃料的热分解和扩散速度,并促进成炭;而EVA/NG、EVA/GO阻燃交联复合材料几乎没有膨胀阻燃效果,GO因为氧化作用其石墨片层受到破坏,阻隔性下降,热稳定性大大降低,因此对阻燃性的提高比较有限,阻燃性和抑烟性均低于NG和EG。⒍无机填充EVA基复合材料的导热与阻燃性能的关系探讨测试和分析无机填充EVA/MDH、EVA/ATH、EVA/EG、EVA/MMT和EVA/Cu复合材料的导热与阻燃性的关系,研究结果表明:无机填充EVA基复合材料的导热系数与点燃时间的变化呈正比例变化关系,可以通过提高EVA的导热性来提高其点燃时间,从而改善其耐燃性。更多还原

【Abstract】 With the continued vigorous development of polymer materials, the resulting fire hidden trouble and fire hazards become important issues of concern. Currently, high-performance, efficient, environmentally friendly flame retardant polymer materials are ever increasing, fire-retardant evaluation methods continue to improve and become more scientific, the more stringent fire regulations, in particular, the EU issued two directives“West Electrical and Electronic Equipment Directive （WEEE）”and“Restriction of Hazardous Substances Directive （RoHS）”, the traditional halogens are faced with severe challenges as flame retardant system, research and development of new efficient halogen-free flame retardant system is very urgent and necessary. The polyolefin materials are widely used in the field of wire and cable. EVA is one important member of the polyolefin materials, its oxygen index is low （<19%）, with higher heat release rate while combustion, and accompanied by melting dripping and a lot of smoke, so it must be modified through flame retardant. In this paper, the EVA with higher VA content （50%） was selected as the matrix resin, peroxide DCP was used as crosslinked agent. Firstly, spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride （SPDPC） was synthesized through simple dehydrochlorination reaction of pentaerythritol （PER） and phosphorus oxychloride （POCl₃）; Secondly, the novel flame retardant （SPDH） containing phosphorus and another novel flame retardant （SPDV） containing phosphorus and silicon with a different molecular structure were synthesized from SPDPC and DOPO derivatives, respectively. The synthesized SPDH and SPDV were used for the flame retardancy in EVA, respectively, and the flame retardant mechanism was investigated. On the other hand, the method of peroxide crosslinking was used, and the flame retardant, mechanical, electrical and thermal aging properties were investigated for the halogen-free flame retardant EVA composites filled with ATH and MDH, respectively. The synthesized SPDV containing phosphorus-silicon was used for the flame retardant optimizing of EVA/MDH cross-linked composites. Meanwhile, the effect of flame retardant properties was studies by OMMT and MWCNTs organically modified with SPDV for EVA-based cross-linked composites. And also, CaCO₃, nature graphite （NG） and expandable graphite （EG） was used respectively for the flame retardant optimizing of EVA/APP/PER/ZB cross-linked composites; NG, EG and graphite oxide （GO） was utilized for the flame retardant of EVA-based cross-linked composites. The relationship between charring and flame retardant properties was analyzed in detail, and the flame retardant mechanism was discussed. Finally, the possible correlation between heat conduction and flame retardancy was studied for EVA-based composites loaded with different inorganic fillers.⑴The synthesis and characterization of new phosphorus-containing flame retardants First, phosphorus oxychloride （POCl₃） was reacted with pentaerythritol （PER） to form a intermediate product named spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride （SPDPC）. After that, the novel flame retardant （SPDH） containing phosphorus and another novel flame retardant （SPDV） containing phosphorus and silicon with a different molecular structure were synthesized from SPDPC and DOPO derivatives. The structure of the intermediate products （SPDPC, DOPO-HQ and DOPO-VMDMS） and the end products （SPDH and SPDV） was characterized by Fourier transform infrared spectroscopy （FTIR）,Nuclear Magnetic Resonance （IH NMR, 31P NMR）. The thermal properties of SPDH and SPDV were investigated by thermogravimetric analysis （TGA） in both nitrogen and air. It was found that SPDV had better char yield in air （44.6%） than in nitrogen at 800℃while SPDH had good char yield only in nitrogen at 800℃, which indicates that oxygen can help the charring progress of silicon-containing compounds and the improvement of heat-resistance for char residue.⑵Research on the effect of flame-retardant cross-linked EVA-based composites by SPDH and SPDV The synthesized two flame retardants （SPDH and SPDV） were used in EVA respectively, and the corresponding halogen-free flame-retardant cross-linked EVA/SPDH and EVA/SPDV composites were prepared by melt blending. The results showed that the PHRR, THR, EHC, and MLR were significantly reduced, and FPI, char yield and LOI were increased for the addition of flame retardants SPDH and SPDV, respectively. UL-94 vertical test indicated that V-2 grade can be obtained by the addition of 20phr flame retardants. It was found that the flame retardant was significantly improved for the cross-linked EVA/SPDH and EVA/SPDV flame retardant composites. The initial decomposition temperature and ignition time was slightly shortened because of the addition of SPDH and SPDV. The smoke production rate （SPR） and total smoke release （TSR） of flame-retardant cross-linked EVA/SPDH composites increased, while TSR was reduced and char residue was enhanced more evidently for flame-retardant cross-linked EVA/SPDV composites, which of the reason was the introduction of silicon-containing compounds promoting the char formation and its thermal stability. It can be found that the char residue presented some small pores for flame retardant cross-linked EVA/SPDH composites while it showed more compact for flame retardant cross-linked EVA/SPDV composites from SEM photos, and EDS results showed that the outer surface of silicon content was higher than that of the inner because of the migration of silicon compounds, which enhanced the thermal stability of the carbon layer.⑶Research on the effect of flame-retardant cross-linked EVA-based composites by nano-flame retardants （MWCNTs, OMMT）The synthesized flame retardant SPDV was used to the organic modification of the MWCNTs to be MWCNTs-g-SPDV, and its structure and thermal stability was characterized by FTIR, NMR, TEM and TGA, respectively. Both MWCNTs and MWCNTs-g-SPDV was utilized to the flame retardant of EVA. It can be found that the thermal stability was improved for flame-retardant cross-linked EVA composites. The PHRR, AHRR were significantly decreased, and TTI, FPI and combustion residue was increased significantly, which indicating that the flame retardant was enhanced significantly; and also the more obvious improvement for the addition of MWCNTs-g-SPDV because of the dispersion of improving in the EVA matrix and promoting the charring while combustion. On the other hand, MMT and OMMT was used in EVA, respectively. XRD and TEM was utilized to the characterization of microstructure for flame-retardant cross-linked EVA/MMT and EVA/OMMT composites. The results showed that the flame resistance was significantly improved for flame-retardant cross-linked EVA/OMMT composites, while it was slight on the improvement of flame resistance for the addition of MMT. This reason was the formation of intercalated structure by OMMT and EVA matrix, and the inorganic montmorillonite layers can migrate to the surface in the combustion process and form similar to the "labyrinth" structure, which played a role in barrier protection and promoted charring.⑷Research on the effect of flame-retardant cross-linked EVA-based composites by inorganic metal hydroxide （ATH, MDH） and its optimization of flame retardant by SPDVIt was composed of different formulations by ATH modified with vinyl methyl dimethoxy silane （VMDMS） and MDH modified with amino silane as flame retardants, respectively, and DCP as a crosslinking agent, DDA as antioxidant. The flame retardant, mechanical, electrical, thermal aging and rheological properties was studied for flame-retardant cross-linked EVA-based composites. The results showed that: the flame resistance was significantly improved for flame retardant cross-linked EVA composites, while tensile strength and elongation at break was decreased, and breakdown strength and volume resistance was decreased slightly, but still maintained a high level, which can meet the requirements used as halogen-free flame retardant cable sheathing materials. It can be found that the temperature level used at long time was improved to 125℃from 105℃rating for the optimized flame-retardant cross-linked EVA/MDH aging formulation. Meanwhile, the synthetic fire retardant SPDV was used to the flame-retardant optimization for flame-retardant cross-linked EVA/MDH composites. The results showed that the flame retardant was further improved, and it presented obvious intumescent phenomenon. The filled MDH can resist the sample deformation and droplet caused by thermal radiation and flame in the combustion process, and the char can obtain a higher intensity and form a swelled structure. The screen barrier and phosphorus/silicon flame-retardant effect was improved, which enhanced the flame retardant efficiency.⑸Intumescent flame retardant cross-linked EVA-based composites and its mechanism of flame retardant propertiesCaCO₃、NG、EG was used to the flame retardant optimization of the EVA/APP/PER/ZB flame retardant cross-linked composites, respectively. The results showed that the PHRR, THR, SPR were further reduced, and FPI, TTI and combustion residues were further increased significantly for optimized composites, which indicating that the flame retardant and smoke suppression was further improved, showing a certain degree of flame-retardant synergistic effect. It can be found that the thermal stability and strength of char residue was increased duo to the addition of CaCO₃, NG, EG, which was the one of important reasons for the improvement of flame retardancy. Further investigation of the flame-retardant cross-linked EVA composites filled with CaCO₃, NG, EG, it can be found that a obvious improvement of flame retardancy and smoke suppression for flame-retardant cross-linked EVA/EG composites, while a relatively low increase of flame resistance for the flame-retardant cross-linked EVA/NG, EVA/GO composites and a slight enhancement of smoke suppression for the flame-retardant cross-linked EVA/GO composites. A very important reason was that a dramatic expansion can be formed to give a protective screen composed of many graphite layers with hollow structure, which can effectively delay the heat, oxygen transfer, reducing the fuel thermal decomposition and diffusion rate, and promote char formation, while there was almost no effect of intumescent flame retardant for flame-retardant cross-linked EVA/NG, EVA/GO composites. The effect of barrier and thermal stability was greatly reduced for EVA/GO composites because of the oxidation damage of GO.⑹Study on the relationship between thermal conductivity and flame-retardant properties of EVA-based composites loaded with inorganic fillersThe thermal conductivity and flame retardant properties were tested and analyzed for inorganic filled EVA/MDH, EVA/ATH, EVA/EG, EVA/MMT and EVA/Cu composites. The results showed that it was a directly proportional relationship between the thermal conductivity and ignition time for EVA based composites, and the improvement of thermal conductivity can improve the flame resistance.更多还原