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类蛭石纳米层状硅酸盐材料的制备及应用研究
刘义
学位类型硕士
导师陈朝阳
2016-05-27
学位授予单位中国科学院大学
学位授予地点北京
学位专业材料工程
关键词类蛭石纳米层状硅酸盐 制备 影响因素 复合材料 力学性能
摘要

层状硅酸盐材料是一类广泛分布于自然界的无机固体材料,由于其出色的吸附、插层、溶胀及离子交换等性能而引起广泛的关注。而层状硅酸盐材料的这些性能使其在高分子材料填料、药物释放系统、吸附剂、催化剂制备及催化剂载体等方面得到应用。但是,由于自然界中存在的层状硅酸盐材料大部分以黏土矿物形式存在,而作为天然矿物,黏土矿物普遍存在含有大量杂质、矿物结构不均一等缺点,严重限制了他们在某些工业领域内的应用。为了获得物相单纯、结构均一的黏土矿物,科研人员进行大量研究,此外,在合成过程中还可以通过控制合成条件来制备定量同晶替代的可控材料。本文主要研究了以下几个方面的内容:首先,运用水热合成法在SiO2-MgO-Al2O3-NaOH-H2O体系中制备得到了类蛭石纳米层状硅酸盐材料(Vermiculite-like Layered Silicate, VLS)。为获得高比表面积的样品,采用不同浓度的HCl溶液对类蛭石纳米层状硅酸盐材料进行酸化处理,通过XRD、SEM及BET分析可知,当HCl浓度为0.7 mol/L时制备得到样品的比表面积最大,为102.7 m2/g。运用硅烷偶联剂乙烯基三甲氧基硅烷(A-171)对制备得到的样品进行了有机改性,通过XRD及SEM分析可知有机改性后的样品层状结构未受影响,由FTIR结果可知硅烷偶联剂成功修饰到层状材料表面。其次,研究了反应温度、反应时间、碱用量及硅源等反应条件对类蛭石纳米层状硅酸盐材料形成及生长的影响,并通过XRD、SEM及XRF对制得样品进行分析。结果表明,温度对类蛭石纳米层状硅酸盐材料的制备影响最大,温度过高或过低对类蛭石纳米层状硅酸盐的形成及生长都不利,最佳反应温度设定在300℃;当反应时间较短时,层状结构形成不完善,而反应时间过长时,制备得到样品中开始出现杂质,因此最优时间选在24 h;碱用量的多少对层状材料的结晶度有着很大影响,随着NaOH用量的增加样品的结晶程度越来越高,但是在文中所述条件下,当SiO2/NaOH摩尔比超过1:2.5时,制备得到样品中开始出现杂质,为获得具有高的结晶度的样品,SiO2/NaOH摩尔比选择1:2.5。最后,以熔融共混法制备SiO2/HDPE、VLS/HDPE及SiO2/VLS/HDPE复合材料,并对复合材料的力学性能及热学性能进行了研究。结果表明,单组分无机纳米粒子/HDPE复合材料的弯曲模量、弯曲强度及拉伸强度都有明显的提高,但是复合材料的冲击强度有了较大幅度的下降;而在双组分SiO2/VLS/HDPE复合材料中,气相法二氧化硅与类蛭石纳米层状硅酸盐材料未能形成协作用,复合材料的力学性能未能达到预期。

其他摘要

Layered silicate materials are one kind of inorganic solid materials which widespread both in nature and in laboratories. These materials are well-known for their remarkable absorption, intercalation, swelling and ion-exchange properties. And these properties pave the way for them use as fillers in polymer nanocomposites, drug release systems, absorbents, catalyst and catalyst supports. But the layered silicate materials occurred in nature often in the form of clays, as a natural mineral, clay mineral have severe drawbacks, such as impurities and structural heterogeneity, which severely limits their applications in some areas. In order to obtain clay mineral which have pure and homogeneous phase, researchers have conducted numerous studies. Moreover, the isomorphous replacement materials also prepared during the synthesis. In this paper, the following three aspects were discussed respectively:First, vermiculite-like layered silicate (VLS) was successfully prepared by hydrothermal synthesis method in the system of SiO2-MgO-Al2O3-NaOH-H2O. In order to obtain samples with large specific surface area, the vermiculite-like layered silicate was treated with different concentrations of HCl solutions, according to the results of XRD, SEM and BET, the samples which had the highest BET was prepared by treated with 0.7 mol/L HCl solution and the largest specific surface area was 102.7 m2/g. Vinyltrimethoxysilan(A-171) was chosen as the silane coupling agent to modify the prepared samples, the XRD and SEM results of organic modified samples revealed that the layered structure still exists and FTIR results showed the the silane coupling agent were successfully modified to the surface of layered materials. Second, the influence of reaction temperature, reaction time, the amount of alkali and silicon source on the formation and growth of vermiculite-like layered silicate were investigated in this paper. By the analysis of XRD, SEM and XRF results, we could got the following conclusions: the reaction temperature was the key influence factor in the synthesis process, either too high or too low was disadvantageous to the synthesis of samples, and the optimum reaction temperature was set at 300℃; when the reaction time was too short, the formation of the layered structure was imperfect, but the impurities was began to appeared when the reaction time was set too long, so the optimal time chose 24 h; the amount of alkali influenced the crystallinity of layered materials greatly, and in order to get samples with high crystallinity, the ratio of SiO2/NaOH was set at 1:2.5.At last, inorganic nanoparticle/HDPE composite materials were prepared by melt blending method, the mechanical and thermal properties of composites was also discussed. The results showed that the mechanical properties (except impact strength) and thermal properties of SiO2/HDPE and VLS/HDPE were improved remarkably. But the mechanical properties of SiO2/VLS/HDPE composite failed to meet expectation, the SiO2 and VLS did not create synergy effect in composite

文献类型学位论文
条目标识符http://ir.xjipc.cas.cn/handle/365002/4588
专题材料物理与化学研究室
作者单位中国科学院新疆理化技术研究所
推荐引用方式
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刘义. 类蛭石纳米层状硅酸盐材料的制备及应用研究[D]. 北京. 中国科学院大学,2016.
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