离子交换法制备LDHs纳米复合材料及其影响因素研究

以层状双金属氢氧化物(LDHs)、氯化镁和氯化铝为原料,通过液相非稳态共沉淀法制备MgAl-Cl-LDHs溶胶,通过离子交换引入己基磺酸钠(SHS),制备SHS-LDHs纳米复合材料,研究了混合溶胶pH值、SHS的初始浓度、碳链长度以及LDHs的浓度对材料性能的影响。研究发现,当混合溶液的pH 7.25,LDHs的浓度不大于0.50%,且SHS的浓度高于20 mmol/L时,CH_3(CH_2)_5SO_3^-才能通过离子交换反应进入LDHs层间,得到SHS-LDHs纳米复合材料。     

纳米插层复合材料制备及应用的研究进展

介绍了纳米插层复合材料的制备方法,并结合层状硅酸盐、聚合物／层状硅酸盐的结构特征,对插层复合的热力学和动力学进行了分析,最后,对纳米插层复合材料的应用前景作了展望。     

AC/LDHs插层复合材料的制备及其在挤出发泡成型中的应用

以苯甲酸插层改性LDHs纳米粉体为交换前体,采用插层置换的方法,制备出一种AC/LDHs新型纳米复合发泡材料.采用XRD、TG-DTA等手段对新材料进行了表征.结果表明pH值是影响插层效果的一个关键因素,且pH=4时,插层效果最好.利用pH=4条件下制备的新型插层复合材料在适当条件下进行挤出发泡成型,可以得到孔径为20～40μm左右的泡孔分布均匀的发泡制品.     

LDHs覆膜改性活性炭对水中磷的吸附特性研究

采用水热共沉淀法合成两种层状双金属氢氧化物(MgAl-LDHs和MgFe-LDHs)覆膜于活性炭,并研究了其对水中磷的吸附特性。结果表明,在pH=7、温度为298.15 K、吸附时间为4 h时,MgAl-LDHs和MgFe-LDHs改性基质对磷酸盐最大理论吸附容量分别为3.158 mg/g和4.557 mg/g。吸附过程更加符合Langmuir等温模型和拟二级动力学吸附模型,以均匀单分子层化学吸附为主。当磷酸盐初始浓度为0.5 mg/L和2 mg/L时,MgAl-LDHs改性基质的饱和吸附容量接近MgFe-LDHs改性基质的2倍,MgAl-LDHs改性基质更适合作为吸附剂。LDHs改性基质吸附磷酸盐的热力学参数ΔG⁰<0、ΔH⁰<0,说明吸附过程是自发的放热过程,低温更有利于提高吸附效果。     

聚合物／层状硅酸盐纳米复合材料的研究进展

聚合物／层状硅酸盐（PLS）纳米复合材料是近十多年迅速发展起来的新交叉科学。由于聚合物纳米复合材料具有常规聚合物复合材料所没有的结构、形态以及较常规聚合物复合材料更优异的物理力学性能、耐热性和气体液体阻隔性能等，因而显示出重要的科学意义和应用前景。综述了聚合物／层状硅酸盐纳米复合材料的制备、结构、性能和应用情况，最后展望了其应用前景。     

聚合物-层状硅酸盐纳米复合材料应用研究进展

笔者论述了聚合物-层状硅酸盐插层纳米复合材料的结构和特点，综述了聚合物-层状硅酸盐纳米复合材料的应用研究进展，评述了聚合物-层状硅酸盐纳米复合材料的制备方法和表征手段，展望了这种纳米复合材料的发展方向。     

阻燃聚合物/LDHs纳米复合材料的研究进展

近年来,聚合物/层状双氢氧化物纳米复合材料受到了国内外学者的广泛研究.层状双氢氧化物(LDHs)是一类具有片层结构的二维纳米材料,将其引入聚合物基体中,可以使复合材料呈现出良好的阻燃性和抑烟效果.但是,由于LDHs在聚合物基体中分散性和相容性较差,因此,在制备复合材料前,通常会先对其进行有机改性.主要总结了LDHs的结...     

氧化铁/层状双金属氢氧化物复合材料的制备

制备由不同结构单元组成的复合材料是提高材料性能的一种有效方法.分别采用两种方式(双滴共沉淀法和LDHs层板附着生长法)制备Fe3 O4/层状双金属氢氧化物(LDHs)复合材料.利用X-射线衍射、电子显微分析和红外光谱等测试方法研究了LDHs和Fe3 O4的复合方式对复合材料形貌、粒径和结晶性能的影响.同时对比分析了两种制备方案得到的Fe3OJLDHs复合材料生长规律.实验结果表明,采用双滴共沉淀法制备的Fe3OJLDHs复合材料具有层状结构和良好的结晶性.     

聚硅酸铝锌絮凝剂的制备及影响因素研究

以硅酸钠、硫酸铝、硫酸锌为原料在高剪切条件下制备出无机高分子聚硅酸铝锌絮凝剂,通过正交实验和单因素优化实验研究了SiO2含量、pH、活化时间、n(Al+Zn)∶n(Si)、n(Al)∶n(Zn)对絮凝剂絮凝效果的影响。结果表明,各因素对絮凝剂絮凝效果影响大小依次为pH>SiO2含量>n(Al+Zn)∶n(Si)>n(Al)∶n(Zn)>活化时间;絮凝剂的最优制备条件:SiO2质量分数为3.0%,pH为3,活化时间为85 min,n(Al+Zn)∶n(Si)为1.5,n(Al)∶n(Zn)为2.0。以此条件下制备的聚硅酸铝锌絮凝剂处理200 mL浊度为200 mg/L的高岭土废水,当其投加量为3 mL时絮凝效果最好。     

微波制备纳米二氧化铈及其工艺因素的考察

以四水硫酸高铈[Ce（SO4）2·4H2O]和氢氧化钠为反应物，表面活性剂聚乙二醇起到分散产物的作用，在微波作用下制备纳米二氧化铈。采用傅里叶变换红外光谱仪、X射线衍射仪、差热-热重联用分析仪和紫外-可见分光光度计对产物进行表征分析。通过考察制备过程中的各个影响因素，得到了制备纳米二氧化铈的最佳工艺条件：氢氧化钠与四水硫酸高铈物质的量比为4．8：1；聚乙二醇的反应用量为8mL，洗涤用量为7mL；无水乙醇的洗涤用量为10mL；微波恒压时间为6min；微波压力为0．14MPa；微波功率为232W；超声波分散时间为10min；微波干燥时间为10min。在最优工艺条件下制备的产物颗粒粒径为24，9nm，在280-400nm对紫外线具有较好的吸收，在可见光区具有较好的透明性，可用在防晒化妆品中作为屏蔽剂。该制备工艺具有易于操作、环保、粒径小等优点。     

油焦浆的制备影响因素的研究

油焦浆是一种新型节能代油燃料,可以有效地代替燃料油直接应用燃油锅炉,其粘度指标符合应用中的要求。本身粘度比较大的油品制备的油焦浆粘度也较大,混合不同粘度的油品制备油焦浆可以降低油焦浆的粘度,提高较大粘度燃料油的应用。复合添加剂可以有效地提高油焦浆的稳定性,使油焦浆能够放置7d不分层。另外,油焦浆的粘度也受温度的影响,它随温度的升高迅速下降。     

金纳米棒合成及其影响因素的研究

利用种子生长法,通过改变体系中表面活性剂的比例或者硝酸银的量或者金种子的量,可制备出不同长径比(Aspect Ratio,AR)的金纳米棒.结果表明,通过改变表面活性剂的比例可以更好地制备出多种长径比的金纳米棒.     

高铁酸盐制备影响因素研究和中试生产装置的开发

为了开发和优化高铁酸盐中试生产装置,通过小试试验对隔膜材料和生产工艺等进行了研究,结果表明,孔径小于5μm的聚偏氟乙烯膜使用寿命较长;母液循环利用提高了药剂利用率、降低制备成本;电解液NaOH不宜饱和,浓度应降低到14～ 16 mol/L; BaFeO4提取率显著高于K2FeO4,低温（5℃）、隔绝空气密封下,保存30 d以上纯度仍在50％左右.根据小试结果,开发了高铁酸盐中试生产装置,产量可达20 g/h以上,生产总成本约为6万元/t.     

Study on preparation of layered double hydroxides (LDHs) and properties of EPDM/LDHs composites

Abstract

The aim of this work was to study preparation and characterisation of layered double hydroxides (LDHs) and their effects on the mechanical and flame-retardant properties of ethylene propylene diene (EPDM) polymer. A series of Mg–Al, Ni–Al, and Cu–Al hydrotalcite-like compounds were prepared. The surface morphology, interlayer space, interlamellar structure, and thermal properties of these LDHs were investigated. Results showed that a best thermal stability could be obtained with Cu–Al–LDHs as the most effective components. EPDM/Cu–Al–LDHs composites were prepared by conventional compounding with EPDM and Cu–Al type of LDHs. The cure characteristics, tensile strength, wear resistant, and flame-retardant properties were investigated. The best properties were observed for 10 phr of Cu–Al–LDHs filled composite, which resulted in no obvious changes of tensile strength, increased thermal stability, 45% decrease in abrasion loss, and 53% increase in vertical burning time, respectively, compared to that of pure EPDM matrix.     

Preparation and properties of LDHs/epoxy nanocomposites

Layered double hydroxides (LDHs)/epoxy nanocomposites were prepared by mixing the amino laurate intercalated LDHs, EPON 828 resin, and Jeffamine D400 as a curing agent. The organo-modified LDHs with hydrophobic property easily disperse in epoxy resin, and the amino laurate intercalated LDHs with large gallery space allow the epoxy molecules and the curing agents to easily diffuse into the LDHs galleries at elevated temperature. After the thermal curing process, the exfoliated LDHs/epoxy nanocomposites were formed. X-ray diffraction was used to detect the formation process of the exfoliated LDHs/epoxy nanocomposites. TEM was used to observe the dispersed behavior of the LDHs nanolayers, and the LDHs nanolayers were exfoliated and well dispersed in these nanocomposites. Owing to the reaction between the amine groups of the intercalated amino laurate and epoxy groups, the adhesion between the LDHs nanolayers and epoxy molecules makes these LDHs/epoxy nanocomposites more compatible. Consequently, the tensile properties from tensile test and the mechanical properties from DMA were enhanced, and the T_g of these nanocomposites from DMA and TMA were increased. Coefficients of thermal expansion (CTEs, below and above T_g) of these nanocomposites from TMA decreased with the LDHs content. The thermal stability of these nanocomposites was enhanced by the well dispersed LDHs nanolayers.     

Preparation and properties of LDHs/polyimide nanocomposites

Layered double hydroxides/polyimide (LDHs/PI) nanocomposites were prepared from solution of polyamic acid (polyimide precursor) and LDH-amino benzoate using N,N-dimethylacetamide as a solvent. LDH-amino benzoate (LDH-AB) was obtained by coprecipitation method. The amino benzoate, grafted on the surface of the Mg/Al nanolayers, as a connector improved the compatibility between the inorganic Mg/Al nanolayers and the organic polyimide molecules. The dispersion behavior of Mg/Al nanolayers was investigated by transmission electron microscopy and X-ray diffraction, indicating that the Mg/Al nanolayers were exfoliated in PI matrix to form LDH-AB/PI nanocomposites. The maximum tensile strength and elongation of the LDH-AB/PI nanocomposites were found with the LDH-AB content of 5 and 4 wt%, respectively. The initial tensile modulus of these nanocomposites was increased with the LDH-AB content. These nanocomposites exhibited higher storage and loss moduli compared to those of pure PI. T_g of these nanocomposites increased with the LDH-AB content. Coefficients of thermal expansion (CTE, below and above T_g) of these nanocomposites deceased with the LDH-AB content. The thermal properties of these nanocomposites were enhanced by the incorporation of Mg/Al nanolayers in PI matrix.     

离子交换膜电解分离溶液中硫酸根离子的实验研究

离子交换膜电解技术,由于膜的离子选择透过性,在分离无机离子和浓缩酸碱方面具有良好的发展前景。本文利用阴离子交换膜电解,分离(NH4)2SO4和CuSO4溶液中的SO42-。通过实验得出了电流密度对阳极浓缩H2SO4浓度的影响、温度和电流密度对电流效率的影响以及不同电流密度下最佳能耗和电流效率。