【作者】 李波；

【导师】 田明；

【作者基本信息】 北京化工大学 ， 化学， 2011， 硕士

【摘要】 本文通过对Casico新概念膨胀型阻燃体系的研究制备及使用氢氧化物、化学膨胀型阻燃剂对三元乙丙橡胶(EPDM)进行阻燃改性较为系统地研究了橡胶(弹性体)的无卤阻燃机理,揭示了各主要因素对阻燃弹性体材料性能的影响规律,为后续工作提供帮助。本文研究了无机氢氧化物的种类及用量、阻燃协效剂、炭黑和增塑剂等对三元乙丙橡胶力学性能和燃烧特性的影响,并分析了燃烧产物的形貌,揭示了它们在EPDM燃烧过程中的作用。结果表明,氢氧化物吸热分解脱水是其进行阻燃的主要原因；高填充氢氧化物的三元乙丙橡胶适用于制备低烟无卤阻燃橡胶材料,但阻燃橡胶的力学性能较低。阻燃协效剂(红磷和硼酸锌)可有效促进成炭,提升材料的阻燃性能,但增大了发烟量。填充炭黑可大幅提升橡胶材料的力学性能和轻微改善阻燃性能；填充适量的石蜡油对橡胶材料的力学性能没有明显影响,但是不利于阻燃,助燃行为突出。通过该种阻燃技术所制备的可挤出成型的无卤阻燃密封条性能优异,最优配方可以实现硬度75±3,拉伸强度接近8MPa,氧指数大于32%,挤出性能按ASTM D2230分级系统B评价可达到9A以上。本论文采用复合型膨胀阻燃剂NP430对EPDM进行阻燃改性,研究了基体中的外加酸源和外加碳源、阻燃剂NP430、增塑剂石蜡油以及多种补强填料对EPDM阻燃性能的影响,探讨了膨胀阻燃橡胶的机理。结果表明,NP430对EPDM具有很好的阻燃效果,发烟量很小；外加酸源乙烯-醋酸乙烯共聚物(EVA)和外加碳源高苯乙烯树脂(HS)具有更好的协同阻燃作用。当基体中EPDM/EVA/HS的比例为80/8.6/11.4,NP430用量为90phr时,复合材料的氧指数可达47.6%。填充石蜡油不影响燃烧膨胀过程但会明显降低阻燃性能；添加少量甲基丙烯酸锌(ZDMA)、酚醛树脂(PF)等有机补强剂对膨胀过程影响很小,而添加炭黑、二氧化硅、碳酸钙、膨胀石墨等无机填料会导致燃烧产物表面有裂缝从而引起气体逸出,严重不利于膨胀过程,无法实现阻燃。在橡胶中填充炭黑等无机物而不影响膨胀阻燃是制备膨胀型阻燃橡胶最大的问题。本文通过分析Casico新概念膨胀型阻燃体系在不同温度下的分解产物研究了Casico阻燃体系的阻燃原理,并且考察了乙烯—丙烯酸酯共聚物、硅橡胶和碳酸钙等配合剂的种类及用量对复合材料阻燃性能的影响。结果表明,乙烯—丙烯酸丁酯共聚物(EBA)最适合为作为聚合物基体,生成的离聚物可以增大材料高温下的熔体黏度；硅橡胶在燃烧过程中生成硅氧烷小分子与有机羧酸钙作用形成硅酸钙,对阻燃性能起着关键的作用；而填充二氧化硅、石英等无机填料会使燃烧产物的表面形面微小的裂缝,不利于阻燃；氢氧化铝可以复配Casico阻燃体系；过氧化物交联对阻燃性能的影响不明显。当EBA/MVQ/CaCO3的配比为50/20/30时,850℃时残渣质量可达原样品的27.2%,远大于理论上氧化钙的质量分数16.8%,此时Casico阻燃体系的阻燃性能最佳,氧指数为32.5%。更多还原

【Abstract】 In this paper, the laws of various ingredients’ influences in halogen-free flame-retardant materials were revealed by studying the new concept intumescent flame-retardant system named after Casico and preparing ethylene-propylene-diene copolymer (EPDM) modified by hydroxides and chemical intumescent flame retardant (IFR) in order to offer help for future research.The burning behaviors of EPDM modified by hydroxides were analyzed by the advanced evaluation method of cone calorimeter. The effects of different additives such as modified hydroxides, synergistic flame retardants (red phosphorus and zinc borate) and plasticizing agent of paraffin oil were minutely discussed. The morphologies of combustion products were also analyzed to reveal their roles of the additives in the combustion process of EPDM. The results showed that the flame-retardant properties of EPDM would be greatly improved when it was filled with a large amount of hydroxides. The flammability parameters also indicated that the red phosphorus and zinc borate might promote the flame resistant performance, but both lead to more smoke; the carbon black was helpful in promoting the flame-retardant properties of EPDM while paraffin oil was harmful evidently. On the mechanical properties, a proper amount of carbon black could be significantly effective. A large amount the hydroxide is harmful owing to the weak interface interaction between it and EPDM matrix, the paraffin oil wasn’t so adverse when it was up to 40 phr. High performance strip could prepared by this by this method, which may achieve the comprehensive properties of 8MP on tensile strength,75±3 on hardness (shore A),32% on LOI and 9A on ASTM D2230 B.In this paper, EPDM modified by IFR (NP430) was studied. The effects of elastomer matrix including extra-added acid source and carbon source such were analyzed. The effects of NP430, as well as the ingredients such as paraffin oil, carbon black, calcium carbonate, silicon dioxide, expandable graphite (EG), zinc dimethacrylate (ZDMA) and phenol resin (PF) on the flammability properties of EPDM were evaluated. The flame retardance mechanism of IFR on rubber was also discussed. The results showed that NP430 exhibited excellent flame resistance to EPDM, and extra-added acid source ethylene vinyl acetate (EVA) and carbon source high styrene resin (HS) could further improve its effect. When the mass ratio of EPDM/EVA/HS was 80/8.6/11.4 and the amount of NP430 was 90 phr, the limited oxygen index (LOI) reached 47.6%. The addition of paraffin oil was evidently harmful to the flame-resistance but little effect on the intumescence during burning. The composite could intumesce well with a small amount of organic particles such as ZDMA and PF. It was also found that the normal intumescence was obviously restrained by adding the inorganic fillers such as carbon black, calcium carbonate, silicon dioxide and expandable graphite, since the gases ran out during combustion. As a result, the role of IFR was greatly weakened.This paper studied the new concept flame-retardant system of Casico which was made up of ethylene-acrylate copolymer, silicone elastomer and chalk. Heat treatment under different conditions has also been performed to obtain insight into the flame retardant mechanism. The combustion products were investigated. The results indicate that the flame retardant mechanism of Casico was complex and was related to a number of reactions, e.g. ester pyrolysis of acrylate groups, formation of ionomer by reaction between carboxylic acid and chalk and formation of an intumescent structure stabilized by a protecting char. The addition of inorganic materials such as silica resulted in cracks in the surface of combustion residue, which is harmful to flame retardancy, but the addition of aluminium hydroxides (ATH) could strengthen the the flame retardancy of Casico system as a absorption of heat. The effect of crosslinking with peroxide DCP was not significant. When the mass ratio of EBA/MVQ/CaCO3 was 50/20/30, the mass ratio of residual was 27.2% at 850℃,which is much larger than the mass ratio of CaO theoretically at the level of 16.8%. Then the flame-retardant system of Casico obtained an excellent flame retardancy, the LOI of that was as high as 32.5%.更多还原