球形氢氧化镁的合成、磷硅改性及阻燃EVA的研究

发布时间：2018-02-24 04:48

本文关键词： 氢氧化镁磷-硅协同效应改性阻燃剂　出处：《河北大学》2015年硕士论文　论文类型：学位论文

【摘要】：氢氧化镁(MH)因其同时具有阻燃、抑烟、良好的热稳定性及环境友好等多重优点,成为世界各国重点研究的一种无机无卤阻燃剂。但目前氢氧化镁由于自身阻燃效率低,其在阻燃应用中添加量大,导致高分子材料的机械性能骤降。改善氢氧化镁的表面性质,从而提高氢氧化镁与高分子材料的相容性,减少氢氧化镁的添加量,成为目前国内外的研究热点。本文采用反向沉淀法制备了花状球形氢氧化镁微球,并利用9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)和γ-环氧丙氧基丙基三甲氧基硅烷(KH560)作为磷源和硅源对氢氧化镁进行表面磷硅改性,在改善氢氧化镁在高分子基体中分散性的同时,提高材料的阻燃性能。本文主要分为以下三部分:第一部分:采用反向沉淀法,以七水合硫酸镁和氨水为原料,合成了具有花状球形的氢氧化镁。同时分别探索了反应物起始浓度、搅拌时间、陈化时间、反应温度和滴加速度对氢氧化镁形貌和粒径的影响。采用扫描电镜(SEM)表征了合成氢氧化镁的形貌和粒径,X射线衍射(XRD)、傅里叶红外光谱(FTIR)表征了其分子结构。结果表明,合成氢氧化镁的最佳条件是氨水浓度为5wt%,硫酸镁浓度为1mol/L,温度为20oC,搅拌时间为10min,陈化时间为1h,滴加速度为3m L/min。随着反应物起始浓度的增加,氢氧化镁的形貌由类球形变成规则的球形,浓度继续增加球形轮廓变模糊,而粒径则随着反应物浓度的增加先变小后增大;搅拌时间增长,氢氧化镁的形貌变规则,粒径也随之减小;一定的陈化时间有利于氢氧化镁由亚稳态结构向稳态结构转变;反应温度过低、过高都不利于氢氧化镁球形的生长;滴加速度越慢,氢氧化镁的形貌越规则,粒径越小。氢氧化镁微球的粒径总体呈现先减小后增大的规律,最小可达500nm,但由于团聚,部分微球粒径大约在1-3μm之间。第二部分:以DOPO和KH560为原料,通过接枝反应合成了磷硅改性氢氧化镁(MHDK)。采用FTIR、XRD表征了其化学结构,FTIR结果显示MHDK出现P-Ar、P-O-Ph、Si-O-Mg、基团峰,同时-OH的数量大大减少。XRD数据显示MHDK没有改变MH的晶型结构,DOPO和KH560仅仅是接枝于MH表面,接触角实验表明MHDK的接触角由8.31o增加到35.96o,疏水性有了一定的提高。热重分析表明改性后的氢氧化镁热稳定性能有了一定的提高,通过残余率可计算MHDK的接枝量约为3%。MHDK的起始分解温度相对于MH提高了20oC。第三部分:将改性前后的氢氧化镁添加到EVA中,制备了MH/EVA及MHDK/EVA复合材料。极限氧指数(LOI)实验表明MHDK能显著提高材料的阻燃性能,50wt%添加量的材料的极限氧指数从28%提高到29.2%,热重分析表明MHDK的加入使材料的热稳定性提高,50wt%MHDK添加量的材料的起始热分解温度提高了25oC,残炭率增加1.4%。对材料的残炭进行了FTIR、SEM分析,结果表明燃烧后的残炭表面残留P、Si元素,残炭中的含磷物质促进材料成炭。同时由于MHDK的增加,残炭内部出现大量孔洞,外部光滑平整无裂痕,且残炭厚度增加,起到了隔热、抑制有害气体溢出的作用。拉伸测试实验结果显示MHDK/EVA复合材料比MH/EVA复合材料的拉伸强度和伸长率增高,表明MHDK与EVA材料的相容性有所增加。MHDK的表面极性有一定的改善,加入MHDK的材料阻燃性能提高,极限氧指数比添加MH的材料提高了1%。同时,MHDK与材料的相容性提高,提高了材料的力学性能。
[Abstract]:Magnesium hydroxide (MH) at the same time because of its flame retardant, smoke suppression, thermal stability and environment friendly multiple advantages, become a focus of research in the world inorganic halogen free flame retardant magnesium hydroxide flame retardant. But at the moment, because of its low efficiency, the added amount of flame retardant in application, so that the mechanical properties of polymer materials. Sag to improve the surface properties of magnesium hydroxide and magnesium hydroxide, so as to improve the compatibility of polymer materials, reducing the amount of magnesium hydroxide, become a hot topic at home and abroad. This paper uses reverse flower ball shaped magnesium hydroxide microspheres were prepared by precipitation method, and the use of 9,10- two hydrogen -9- oxa phosphaphenanthrene -10- -10- oxide (DOPO) and gamma glycidoxypropyl trimethoxysilane (KH560) as the source of phosphorus and silicon source of magnesium hydroxide were surface modified with phosphorus and silicon, in the improvement of magnesium hydroxide in polymer dispersion at the same time,. Flame retardant high performance materials. This paper is mainly divided into the following three parts: the first part: by reverse precipitation method with seven water Magnesium Sulfate and ammonia as raw materials, with the synthesis of spherical flower like magnesium hydroxide. At the same time respectively to explore the initial concentration of reactants, stirring time, aging time, the effects of reaction temperature and dropping speed of the morphology and particle size of magnesium hydroxide. Using scanning electron microscopy (SEM) characterization of the morphology and particle size of magnesium hydroxide, X ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) characterization of the molecular structure. The results show that the best conditions of the synthesis of Magnesium Oxide's hydrogen ammonia concentration is 5wt%, the Magnesium Sulfate concentration is 1mol/L, temperature 20oC, the stirring time was 10min, the aging time was 1H, 3M L/min. with the increase of initial concentration of reactants dropping, magnesium hydroxide morphology from spherical into regular spherical, with increasing concentration of spherical contour Fuzzy, and the particle size with increasing reactant concentration decreases first and then increases; stirring time increases, the morphology of magnesium hydroxide change rule, particle size decreases; the aging time is conducive to the transformation of magnesium hydroxide from the metastable structure to the stable structure; low reaction temperature is too high, is not conducive to the growth of spherical magnesium hydroxide; dropping speed is slower, the more regular morphology of magnesium hydroxide, the smaller the particle size of magnesium hydroxide. The particle size of the microspheres showed decreased first and then increased the law, the minimum of up to 500nm, but because of agglomeration, particle size of about 1-3 parts. The second part: m between DOPO and KH560 as raw materials, was synthesized by grafting reaction phosphorus silicon modified magnesium hydroxide (MHDK). Using FTIR, XRD characterization of the chemical structure of FTIR, the results showed that MHDK P-Ar, P-O-Ph, Si-O-Mg, and -OH groups of peaks, greatly reducing the number of.XRD data show that MHDK did not change MH The crystal structure of DOPO and KH560 is grafted on the surface of MH, the contact angle experiments show that the contact angle of MHDK increased from 8.31o to 35.96o, the hydrophobicity is improved. Thermogravimetric analysis showed that thermal stability of modified magnesium hydroxide has been improved to some extent, the grafting amount can be calculated by the residual rate of about MHDK 3%.MHDK the initial decomposition temperature higher than MH 20oC. in third parts: before and after the modified magnesium hydroxide added to the EVA, MH/EVA and MHDK/EVA composite materials were prepared. The limiting oxygen index (LOI) experiments showed that MHDK could significantly improve the flame retardant properties of materials, the limiting oxygen index of adding amount of 50wt% material increased to 29.2% from 28%, thermogravimetric analysis showed that the addition of MHDK can improve the thermal stability of the materials, the amount of 50wt%MHDK the initial thermal decomposition temperature of the material increases 25oC, carbon yield increased 1.4%. of carbon materials were investigated by FTIR, SEM analysis. The results show that the residual carbon surface residue after combustion of P, Si elements, phosphorus carbon residue in promoting material into carbon. At the same time as the MHDK increases, the residual carbon inside a large number of holes, external smooth cracks, and the residual carbon thickness increases, to heat insulation, inhibit harmful gas overflow effect. The tensile test the experimental results show that the MHDK/EVA composite is MH/EVA tensile strength and elongation of the composite increased, indicating that MHDK and EVA compatibility of materials increased.MHDK surface polarity has a certain improvement, improve the flame retardant properties of materials of joining the MHDK, the limiting oxygen index was increased by 1%. and MH than adding materials, improve the compatibility of MHDK and materials the mechanical properties of the materials were improved.

【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ132.2;TQ325

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