高岭土插层与剥离影响因素的研究

采用混合-静置法制备了高岭土/乙酸钾插层复合物,考察了含水量和温度对插层反应的影响,同时研究了不同剥离方式和插层率对插层复合物剥离效果的影响。结果表明,插层反应体系中少量的水有利于插层反应的进行,在20℃下反应24 h即可达到91%以上的插层率,无需搅拌和高温等其他能耗。高温水洗法和超声水洗法剥离效果较好,插层率越高的复合物剥离后晶粒厚度越小。     

插层反应前高岭土的超声酸活化实验研究

以苏州高岭土为原料,在插层反应前用超声波和盐酸对其活化,制备了高岭土/DMSO插层复合物.通过比表面积(SSA)、FTIR和XRD等表征,探讨了超声时间和盐酸浓度对高岭土物性变化以及超声酸活化对插层反应的影响.结果表明:高岭土的比表面积随着盐酸浓度的增加和超声时间的延长而增人;超声处理未造成高岭土的晶化和层状结构的破环,不影响四面体匀称性;超声酸活化过程中,高岭土发生了一定程度的层离和层间距的增加,提高了插层率.     

超声波法制备高岭石插层复合物

用超声波法制备了高岭石插层复合物.利用红外光谱、X射线衍射和透射电子显微镜分析了不同产地高岭石结构的差异、插层效果以及它们之间的关系.比较了不同类型插层剂与高岭石的插层产物、插层效果及插层机理.结果表明:相同条件下,多水高岭石(埃洛石)和结构压力大的管状高岭石比普通高岭石更易于插层.在60℃,3 h,超声波条件下,将高岭石/二甲基亚砜(dimethylsulphoxide,DMSO)作为媒介,采用两步插层法快速制备高岭石/乙醇前驱体,但DMSO的插层率优于乙醇的.甲醇钠与苏州高岭石作用后,使部分苏州土片层间剥离.     

硫脲插层高岭土复合物的制备及表征

以二甲基亚砜(DMSO)为插层前驱体,采用超声处理法制备了高岭土-二甲基亚砜(DMSO-Kaol)插层物,再用甲醇(MOH)取代DMSO,制备预插层复合体(MOH-Kao),最后采用插层取代法,用硫脲分子(TU)取代MOH,制备了TU-Kaol插层复合物。产物插层率达到81.3%。通过傅立叶变换红外光谱(FTIR)、X射线衍射(XRD)和热重分析法(TGA)进行了表征,并对反应过程及产物分子排布进行了预测。为硫脲插层高岭土复合物用于高分子阻燃改性提供了理论及实验依据。     

聚甲基丙烯酸甲酯/高岭土复合材料的制备与性能研究

本文以煤系高岭土为原料,制备有机高岭土为前驱体,将甲基丙烯酸甲酯和前驱体通过原位聚合反应得到复合材料.通过FTIR和XRD等方法,探讨了复合物的结构;并通过一系列表征手段对复合物性能进行了考察.结果表明:本文制备得到的PMMA/高岭土复合物属于剥离型聚合物/层状硅酸盐复合材料,高岭土的插层提高了PMMA的热稳定性、阻燃性和抵抗弹性变形的能力.     

定向制备不同尺寸的3D掺氮石墨烯及其表征

利用改进的Hummers方法经冷冻干燥制备氧化石墨(GO),通过温和磁力搅拌、普通超声和大功率超声3种剥离方式,经一步水热法合成了3D掺氮石墨烯。通过FT-IR、XRD、FESEM、EDS、Raman、XPS、TGA、AFM对样品的微观形貌和结构进行表征。结果表明,通过不同的剥离方式可以得到不同形貌、不同尺寸、不同厚度、不同掺氮含量的掺氮石墨烯。温和磁力搅拌不会对片层结构有较大破坏,可制备微米级大尺寸掺氮石墨烯,厚度约为1.1 nm。在普通超声下,掺氮石墨烯片层开始产生孔状结构,厚度约为0.8 nm。在大功率超声波的空化效应作用下,片层剥离程度较普通超声更为明显,更易形成较小尺寸的3D多孔网络结构,厚度约为0.6 nm。     

超声法制备高岭土/二甲基亚砜插层复合物的影响因素

以苏州高岭土为原料,采用超声波法快速制备了高岭土/二甲基亚砜插层复合物,用X射线衍射和红外光谱进行了表征.通过正交实验分析了反应时间、超声波强度、含水量和反应温度等因素对插层率的影响.结果表明:反应时间从1 h增加到5h可使插层率增加53.44%,影响最为显著;超声波强度次之;由于实验用高岭土含水量较多,使得水的影响弱化;而超声波提供的局部高温高压的特殊环境,使温度对反应的影响最小.最优化条件为:反应时间4h,超声波强度为200 W,含水量10%、温度为90℃,在此条件下,插层率达到92%以上.     

煤系高岭土的制备及其在涂料中的应用研究

以煤系高岭土矿为原料,丙三醇为插层剂,采用超声辅助液相插层工艺,经湿法球磨、喷雾干燥、旋风分离、焙烧后制备煤系高岭土,并对其微观形貌进行了表征。以所得煤系高岭土为原料制备水性环氧内墙仿瓷涂料,并和市场上的同类产品进行对比研究,采用白度仪、反射率测定仪、紫外灯照射、冷热循环、耐洗刷仪测定涂层各项性能。结果表明:采用超声辅助液相插层法制备的高岭土其形貌、粒度、白度与钛白粉相近,优于市售同类产品;与钛白粉按质量比4∶6掺杂制备涂料时实现了协同效应,在白度、遮盖力、耐紫外、耐干擦、耐冷热循环方面都优于市售高岭土和钛白粉复配效果,可显著降低涂料成本。     

基于正交实验法的高岭土前驱体的制备

实验采用超声波插层与机械加热搅拌插层相结合,利用二甲基亚砜、尿素、甲酰胺和乙酸钾对高岭土进行一次插层;利用丙烯酰胺、乙酸铵、三已醇胺对高岭土进行二次插层改性。采用正交实验设计,通过改变高岭土及一次二次插层剂的添加剂量、超声反应温度、插层时间等,得到16组样品。利用红外光谱仪、X射线衍射仪及扫描电镜等对样品进行表征,发现经过改性后的高岭土前驱体的插层效果较好,其中高岭土3g时,一次插层剂为甲酰胺,二次插层剂为三乙醇胺时对高岭土改性在增加层间距以及结构稳定性方面的效果最好。     

煤系高岭土插层-水热法制备亚微米级13 X分子筛

以煤系高岭土为原料,制备了高岭土/二甲基亚砜插层复合物,并对产物进行表征,结果表明,在60 ℃超声水浴插层处理3 h,700℃热处理的插层剥离效果较好,制得的偏高岭土的粒径为100~900 nm.以制得的偏高岭土为原料,采用水热法成功制备了亚微米级13X沸石分子筛.利用XRD、SEM和静态饱和吸水量测定等手段对不同预晶化过程、晶化时间下制备的产物进行分析,并对亚微米级13X分子筛的生长过程进行了研究.预晶化时间4 h,晶化时间24 h条件下,制备的13X沸石分子筛晶体呈八面体晶型,形状规则,大小均一,粒径为100 nm,其相对结晶度为90.72%,静态饱和吸水率达33.17%.比表面积为909 m2/g,总微孔容为0.15 cm3/g,孔径大小为33×10-9μm.     

高岭土/NR插层纳米复合材料的结构和阻燃性能研究

采用两步插层法制备高岭土／NR插层纳米复合材料，并对其结构和阻燃性能进行研究。结果表明，在二甲基亚砜以及带有环氧基团的改性剂的分别作用下，NR大分子链实现了对高岭土的插层，高岭土片层以纳米尺寸均匀分散在NR中；与NR和填充型高岭土／NR复合材料相比，高岭土／NR插层纳米复合材料的热释放速率和质量损失均减小，阻燃性能得到改善。     

An insight on the weakening of the interlayer bonds in a Cameroonian kaolinite through DMSO intercalation

In this study, intercalation of dimethylsulphoxide (DMSO) in a Cameroonian kaolinite is used to achieve weakening of the interlayer hydrogen bonds, in the perspective of dispersion or even exfoliation of the clay within polymer composite materials. Displacement of intercalated DMSO by ethyl acetate and ammonium acetate is studied in order to simulate the interactions with the polymer matrix. The exfoliation of the kaolinite is well evidenced by X-ray diffraction and SEM observations. The disruption of the interlayer bonds is shown by the displacement of the FT-IR vibration modes of both Al–OH and Si–O functions, and by the decrease of the dehydroxylation temperature recorded by Controlled Rate Thermal Analysis. Complete displacement of DMSO by ethyl acetate is achieved and the crystalline structure is deeply disordered as a result of interlayer bonds weakening. The displacement of DMSO by ammonium acetate leads to a ternary composite of DMSO/ammonium acetate with respective intercalation ratio of 62.4% and 57.7%.     

阳离子型Gemini表面活性剂改性膨润土的制备及结构表征

以膨润土为原料,以系列阳离子Gemini表面活性剂(Gm-n-m)为插层剂制备了有机膨润土,利用红外光谱、X射线衍射及差热-热重分析对产物结构进行了表征,并探讨了温度、时间、搅拌速率及插层剂用量对有机膨润土结构的影响。结果表明,当Gm-n-m分子进入到膨润土层间后,其疏水性增强,层间距由1.51 nm增大到3.91 nm,有机物含量达到23.53%,且层间距明显大于单链CTAB改性膨润土的层间距。适宜的制备条件为:插层剂用量为钠基膨润土的40%,70℃下水浴反应3 h,搅拌速率为205 r/min。     

Intercalation and viscoelasticity of poly(ether-block-amide) copolymer/montmorillonite nanocomposites: Effect of surfactant

A poly(ether-block-amide) copolymer (PEBA) was successfully hybridized with montmorillonites using melt processing techniques to form nanocomposites. The organoclays used in preparation of the nanocomposites were modified with ammonium surfactants of different molecular structures to study the effect of the surfactant on the intercalation and exfoliation of the polymer by X-ray diffraction (XRD) and dynamic linear viscoelastic analysis. The polymer was found to be capable of forming intercalated composite with unmodified montmorillonite and the best intercalation and exfoliation was found in the hybrids using surfactants that possess hydroxyl group. Organoclays modified with a single tallow tail ammonium prevailed over those modified with a double tallow tail ammonium in intercalation and exfoliation of silicate layers. Higher capacity of ion exchange also led to a better intercalation for hybrids using single tail surfactants, but the hybrids with swallow tail surfactant behaved oppositely. XRD data showed that the diffraction peaks in the hybrids were narrower than those of the organoclay implying a higher order and more number of layers in the stacks of clays. The intercalation of nanocomposites was found dominated by the energetic factor and entropic factor played no role in the outcome of intercalation. Results of linear viscoelastic measurements paralleled those of XRD showing that melts of those nanocomposites with a superior intercalation or exfoliation also exhibited higher storage modulus and thus the linear viscoelasticity could be an indicator for intercalation. The composites showed an abnormal terminal behavior suggesting the existence of a network structure.     

以煤系高岭土为原料合成ZSM-5分子筛

在综述有关国内外煤系高岭土的开发应用及使用高岭土合成分子筛的研究、ZSM-5分子筛的合成方法基础上,运用XRD等现代分析测试技术对以高岭土为原料合成ZSM-5分子筛的工艺条件和产品进行探究,初步确定了晶化时间为72 h,晶化温度为160℃,模板剂的加入量与硅的比为0.3︰1,是合成ZSM-5分子筛的适宜条件。     

PA6/蒙脱土熔融插层复合材料结构与性能分析

通过熔融共混法插层复合制备了聚酰胺(PN)6／蒙脱土纳米复合材料，测试了力学性能并对不同蒙脱土含量的PA 6／蒙脱土纳米复合材料进行了对比。实验表明，通过熔融插层可使PN 6基体插层于蒙脱土中，所得到的复合材料的性能较PN 6有很大提高。蒙脱土特殊的层状结构使得利用熔融共混在机械力的作用下插层到纳米级复合材料成为可能。     

Effect of synthesis method on solvation and exfoliation of graphite oxide

Graphite oxides (GOs) synthesized by Brodie’s and Hummers’ methods are significantly different with respect to hydration, solvation and exfoliation properties. Hummers GO is more easily intercalated by liquid water and alcohols, exhibiting osmotic type of swelling. In contrast, Brodie GO shows crystalline swelling in alcohol solvents with step-like insertion of methanol or ethanol monolayers. However, the stronger hydration and easier dispersion in water observed for Hummers GO do not correlate with better dispersion of graphene powder obtained by thermal exfoliation. Higher surface area graphene powder was obtained by exfoliation of Brodie GO, while the temperature of its exfoliation is about 75 °C higher than that for the studied sample of Hummers GO. It is suggested that higher exfoliation temperature and better crystallinity of GO are important factors for preparation of graphene powder using thermal exfoliation.     

高岭石有机插层复合材料的研究及应用现状

高岭石是一种层状硅酸盐矿物,有机物可进入其层间形成高岭石有机插层复合物。本文综述了高岭石有机插层复合物的发展及其制备,分析了高岭石插层复合物的插层反应特点和插层影响因素,并概述了该领域目前的研究重点和应用前景。     

Processing of transmission electron microscope images for quantification of the layer dispersion degree in polymer‐clay nanocomposites

Quantification of the layered silicates dispersion level is necessary to more accurately evaluate the performance in polymer/clay nanocomposites. In this article, a new approach is developed to quantify the degree of exfoliation, intercalation, and immiscibility of layered silicates in polymer matrix, based on bright‐dark pixel measurement (BDPM) in transmission electron microscope (TEM) images. Several examples of exfoliated, intercalated, and immiscible composites with different polymer and clay systems were examined. The method is capable of estimating the percent contribution of all morphologies present in the image. Comparing with X‐ray diffraction (XRD) evidences, it is indicated that as a rule of thumb, the exfoliated structure is dominant whenever the exfoliation percent calculated by BDPM methodology is over 65%, no matter what kind of clay or polymer matrix is used. The intercalated structure can be ascribed to the images with exfoliation level less than 65%, but with the intercalation degree over 28%. Application of this method can facilitate the modeling or correlation of various nanocomposite properties with respect to exfoliation degree. A quantified relation is also possible between XRD and TEM using this approach. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009