有机蒙脱土的制备及性能表征

以天然蒙脱土(MMT)为原料,用季铵盐和氨基酸作为有机插层剂与蒙脱土层间的阳离子进行交换,优化反应条件(改性时间、温度和搅拌速率),制备出层间距不同的有机蒙脱土,用FT-IR、XRD、TEM及TG对产物进行表征.结果表明,4种有机插层剂都已进入蒙脱土的层间,蒙脱土的层间距由1.25 nm增加到1.82～4.05 nm,其中,以1631-Cl为插层剂,改性时间为4 h,改性温度为80 ℃,搅拌速率为300 r/min时,制得的有机蒙脱土层间距大且晶形良好.     

二次插层法制备有机蒙脱石的研究

用甲基丙烯酰氧乙基三甲基氯化铵和十六烷基三甲基溴化铵作为插层剂,采取二次插层法制备了有机化蒙脱石,并对一次插层法和二次插层法的效果进行了比较,结果表明,经过二次插层反应后,蒙脱石的层间距从1nm左右增大至3nm,有利于有机分子的进入和形成新的蒙脱石有机复合物。     

溶液插层法制备CR/有机蛭石纳米复合材料的研究

采用溶液插层法制备CR／有机蛭石纳米复合材料，探讨CR插入有机蛭石的作用机理，研究溶剂种类、插层温度、插层时间和有机蛭石用量对插层效果的影响。结果表明，CR溶剂为四氢呋喃、插层温度为65℃、插层时间为48h、有机蛭石用量为3～5份时，插层效果良好。     

有机插层剂对聚酰胺6／MMT纳米复合材料制备的影响研究

以烷基胺、季铵盐和氨基酸作为有机插层剂与蒙脱土片层进行阳离子交换，制备出层间距不同的有机蒙脱土。采用熔融插层法和原位聚合法分别制备聚酰胺（R％）／蒙脱土（MMT）纳米复合材料，并利用XRD、FT-IR、TEM对有机蒙脱土及纳米复合材料进行结构表征。研究结果表明：用烷基胺、季铵盐和氨基酸有机插层剂改性的蒙脱土层间距由原来的1．25nm分别增大到3．21nm、3．99nm和1．82m；季铵盐有机插层剂更适用于熔融插层法制备PA6／MMT纳米复合材料，而氨基酸有机插层剂更适用于原位聚合法制备PA6／MMT纳米复合材料。     

有机粘土/聚烯烃弹性体纳米复合材料的结构与性能

采用熔体插层法制备有机粘土/聚烯烃弹性体(POE)纳米复合材料,研究有机粘土起始片层间距及用量对复合材料结构与性能的影响.结果表明:POE分子链插层进入有机粘土片层之间形成插层结构,并且有机粘土起始层间距越大,所制备纳米复合材料的物理性能越好.随着有机粘土用量的增大,有机粘土/POE纳米复合材料物理性能逐渐提高.     

改性剂种类对蒙脱土结构和性能的影响

为增加蒙脱土(montmorillonite,MMT)和有机物的相容性和研究插层剂种类对MMT结构和性能的影响,采用Cu,Co和Ni无机金属阳离子,十二烷基磺酸钠、十二烷基硫酸钠、α-烯烃磺酸盐和十二烷基苯磺酸钠等有机阴离子表面活性剂及十六烷基氯化吡啶、十六烷基三甲基溴化铵、十二烷基三甲基溴化铵等有机阳离子表面活性剂作为改性剂,对蒙脱土进行一次改性和二次改性,制备出一系列改性蒙脱土.研究了改性剂种类、插层方式、插层次序对插层效果的影响.X射线衍射分析表明:一次改性时,插层剂均能进入蒙脱土的层间,改性土的层间距由1.04nm增加到1.7～3.52nm;二次改性时,先阳离子后阴离子的插层顺序有利于层间距增大(4.14nm),还可利用配位作用将二次改性剂引入金属离子一次改性MMT中,使层间距增大.改性机理研究认为:阳离子改性机理为层间离子交换,而阴离子改性机理是改性剂和MMT表面形成了氢键.沉降实验表明一次改性土和二次改性土在有机溶剂中分散能力有所增强.     

用乳液插层法制备丙烯酸丁酯/有机蒙脱土纳米复合材料

用乳液插层法制备了丙烯酸丁酯/有机蒙脱土纳米复合材料。先将钠基蒙脱土有机化,然后用乳液聚合法反应制得纳米复合材料。X射线衍射分析表明,蒙脱土有机化后层间距增大,季铵盐插层进入蒙脱土层间,乳液聚合后层间距进一步增大,聚丙烯酸丁酯插层到蒙脱土层间,得到丙烯酸丁酯/有机蒙脱土纳米复合材料。动态力学分析表明,复合材料的储能模量大大提高,损耗因子几乎不变。     

载银和有机化蛭石的制备及其抗菌性能

对蛭石钠化处理后,通过离子交换法对蛭石进行载银和有机化插层改性,制备了3种抗菌蛭石。通过抑菌圈和抗菌率实验研究了其抑菌抗菌性能和机理,用热重和X射线衍射分析了改性蛭石的抗菌持久性和层间结构。结果表明:载银、用十六烷基三甲基溴化铵有机改性、载银并有机改性的3种蛭石均对大肠杆菌和金黄色葡萄球菌具有明显的抑菌圈,对大肠杆菌和金黄色葡萄球菌的抗菌率均达到99.9%以上,所制备的抗菌蛭石具有极强的广谱抗菌能力;抗菌蛭石在水中浸泡60 d后仍具有长效抗菌性;有机改性蛭石的层间距由0.99nm可增大到4.33nm,其层间含有大量的有机插层剂,这为制备结构均匀的蛭石/有机复合材料提供了可能。     

季铵盐插层钠基蒙脱土的工艺研究

采用溴化十六碳烷基三甲铵对钠基蒙脱土进行改性,研究了反应温度、反应配比、反应时间和搅拌方式对蒙脱土插层效果的影响。FTIR证明有机插层剂已进入蒙脱土的层间;XRD结果表明蒙脱土的层间距由1．4nm增加到2．8～3．9nm;TEM观察表明蒙脱土的层间距增大。     

RPUF／蛭石复合材料的制备及阻燃性能研究

用酸化、钠化对蛭石进行结构修饰,以十六烷基三甲基溴化铵(HDTMA·Br)为插层剂,制备了有机化蛭石(OVMT)。XRD 分析表明:HDTMA~ 已完全插层,蛭石的层间距由改性前的1.49 nm 增大到4.53 nm。将 OVMT与聚磷酸铵(APP)复配用于硬质聚氨酯泡沫塑料(RPUF)的阻燃,氧指数测试得出:当 OVMT 和 APP 添加量分别为5%和10%时,极限氧指数达到26.8%,比单独添加7%OVMT、10%APP 分别高出5.4%和3.2%;DSC 和 TG测试表明:与纯 RPUF 相比,复合材料吸热峰温度从358.1℃提高到369.6℃。     

Al-substituted tobermorite: shows cation exchange

It has been found that the tobermorite family--fundamental to cement chemistry can exhibit base exchange behavior. Several Al-substituted tobermorites were synthesized and these 11Å type tobermorites were discovered to have cation exchange as well as selective cation adsorption properties. For example, Al-substituted tobermorite (synthesized from a mixture of clinoptilolite and mortar) has a cation exchange capacity of 56 meq/100g and a selective Cs adsorption K_d of 3400 (ml/g). The cation exchange and selective properties of Al-substituted tobermorite are analogous to those of zeolites because of its rigid structure but unlike those of smectites or vermiculites where the basal spacing varies with the nature of the interlayer cation.     

X-ray diffraction studies of the thermal behaviour of commercial vermiculites

For the purpose of knowing the vermiculites which would have larger capability to retain contaminating substances heating commercial samples from different places have been identified and their thermal behaviour at several temperatures has been investigated by X-ray diffraction (XRD), electron microprobe, thermal analysis (TG and DTA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).The commercial vermiculites can be divided into two types: type 1 (Sta. Olalla, Piauí and Goiás) with Mg²⁺ and K⁺ (< 1) as the principal cations in the interlayer space, and type 2 (China E, China W, China G and Palabora) with K⁺ (approximately = or > 1) and/or Na⁺ and/or Ca²⁺ with or without Mg²⁺ as the principal interlayer cations.The process of dehydration in situ with the temperature seems restricted to interlamellar water monolayers of 1-WLHS type-1 of vermiculites, without dehydration to a zero-water-layer-hydration state (0-WLHS) and the dehydroxylation starts at lower temperatures than in vermiculites of type 2. The maximum hydration state exhibited by the type-2 samples at ambient temperature was equal or lower than the monolayer hydrate, the dehydration process in situ with the temperature was slower and the dehydrated vermiculite coexists with a mica-like structure.The behaviour of vermiculites at elevated temperature examined in situ can be understood considering that the vermiculites constitute a complex system not necessarily in equilibrium and where kinetics plays an important role.Commercial vermiculites heated abruptly at 1000 °C during 1 min transform to mica-like or mica-like coexisting with enstatite, in contrast to the purest Sta. Olalla vermiculite, with only magnesium interlayer cations, which changes to enstatite.     

高岭石有机插层反应的影响因素

利用高岭石的层状结构特征,将有机分子插入高岭石层间形成的高岭石有机复合物,兼具粘土矿物和有机物的特性,是一种新型矿物材料,在功能填料、陶瓷材料、催化剂、择吸附剂、环境修复材料等方面具有广泛的应用前景。高岭石层间氢键作用较强,有机分子的插层作用比较困难,合理控制插层条件是插层作用完成的关键。评述了高岭石特征、插层有机分子性质、水、温度、压力、PH值等因素对高岭石有机插层作用的影响。     

EVA/有机改性累托石复合泡沫材料的制备与性能研究

采用十二烷基三甲基溴化铵（DTAB）对累托石（REC）进行有机处理制备出有机改性累托石（OREC），通过熔融插层法制备出了乙烯-醋酸乙烯共聚物/有机改性累托石（EVA/OREC）复合泡沫材料。利用傅里叶红外光谱仪（FTIR）、X射线衍射仪（XRD）、扫描电子显微镜（SEM）、万能试验机等对复合材料的形貌和力学性能进行了表征，研究了累托石的层间距、含量对复合泡沫材料力学性能的影响。结果表明，经有机改性后累托石层间距增加了10.9 %；复合材料的拉伸强度、断裂伸长率、撕裂强度也随之明显升高；且当OREC质量组分为10份时材料的各项力学性能达到最佳。     

Poly(methyl methacrylate)/montmorillonite nanocomposites prepared by bulk polymerization and melt compounding

This article focuses on structural, thermal, and mechanical properties of nanocomposites in dependence of preparation method and poly(methyl mathacrylate) (PMMA)/organically modified montmorillonite (OMMT) ratio. PMMA/OMMT nanocomposites were prepared by bulk polymerization and by melt compounding. Properties of nanocomposites of the same composition prepared by the two methods were compared. It was observed that nanocomposites prepared via melt compounding at 200°C had a highly oriented structure with lower interlayer spacing values than nanocomposites prepared via bulk polymerization. Two reasons for the observed smaller interlayer spacing obtained by melt compounding were identified. The first is enhanced PMMA penetration and/or formation between layers in the case of bulk polymerization, which was confirmed by determination of stronger interactions between OMMT and PMMA by Soxhlet extraction, infrared spectroscopy, and differential dynamic calorimery. The second reason for smaller interlayer spacing for nanocomposites prepared by melt compounding is organic modifier degradation during melt compounding process, which was confirmed by thermogravimetric analysis. Both reasons lead to the fracture of melt compounded nanocomposites on the OMMT‐polymer interface, which was observed by scanning electron microscopy. For nanocomposites with disoriented structure and larger interlayer spacing prepared via bulk polymerization the fracture occurred in the polymer matrix. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Temperature effects on iodine adsorption on organo-clay minerals: II. Structural effects

Smectites and vermiculites modified with hexadecylpyridinium (HDPy⁺), hexadecyltrimethylammonium (HDTMA⁺), benzethonium (BE⁺) and dipyridinododecane (DPyDD²⁺) cations exhibit high adsorption capabilities for the anionic radionuclide ¹²⁵I⁻ (Part I of this article). In some cases, exposure to higher temperature decreased the anion adsorption. To clarify the mechanisms of temperature dependence of the investigated organo-clay minerals, structural properties and thermal stabilities were examined by in situ powder X-ray diffraction (XRD), thermogravimetry (TG), thermocalorimetry (DTA) and FTIR spectral analyses.The organic cations HDPy, HDTMA and BE form bilayers, pseudotrimolecular layers and paraffin-type structures. The basal spacings of DPyDD-smectite and DPyDD-vermiculite were more or less unchanged in comparison to the original clay minerals (1.4 nm). It is assumed that the anion adsorption is due to the uptake of organic cations in an excess of the CEC, predominantly in the interlayer spaces as ion pairs.The decreasing iodide adsorption with increasing temperature is probably due to conformational changes of the alkyl chains, which are most pronounced for DPyDD-vermiculite at 60 °C (1.48→1.20 nm). Additionally, dehydration reactions, which occur at distinct temperatures for the organo-vermiculites (HDPy, 71; HDTMA, 57, 72; BE, 61; DPyDD, 41 °C), may be another reason for a decrease in iodide adsorption. The thermal decomposition of the organic cation starts at 200 °C. The HDPy, HDTMA and DPyDD-smectites and the HDTMA and BE-vermiculites show a high thermal stability with the basal spacing remaining constant up to 150 °C, which recommends the use for anion retention in engineered barriers for heat-producing waste.     

Thermal characteristics of organoclay and their effects upon the formation of polypropylene/organoclay nanocomposites

Summary We have examined thermal characteristics of two types of organically modified montmorillonite (OMMT) with different alkylammonium cations and their effects upon the formation of PP nanocomposite, when using a maleic anhydride grafted polypropylene oligomer (maPP) as a compatibilizer. The microstructure of the composite has been characterized by X-ray diffraction (XRD) analysis, transmission electron microscopy and Fourier transform infrared spectroscopy. OMMT showed the decrease of the interlayer spacing at the processing temperature, due to the release of organic ion by thermal decomposition. Thermal characteristics of OMMTs depended greatly on the interlayer structure of OMMT. When the OMMT with small interlayer spacing and less organophilicity was used, PP composite resulted in the only partial exfoliation due to thermal decomposition of the clay layers. Received: 21 June 2000/Revised version: 11 August 2000/Accepted: 11 August 2000     

Microstructural changes of reference montmorillonites by cationic surfactants

The characteristics of montmorillonites modified with the cationic surfactant hexadecyltrimethylammonium (HDTMA) were evaluated by investigating adsorption isotherms and microstructures. The interlayer structure of montmorillonite intercalated with alkylammonium cations was affected by several factors: the density of the layer charge, degree of exchange, and mutual interaction between alkyl chains. Especially, the surface charge appeared to have an influence on interlayer expansion as a function of surface coverage. Our transmission electron microscopy (TEM) data on the montmorillonite treated with HDTMA revealed that different types of organic derivatives with distinct swelling patterns occurred as a result of the different layer charge densities or distributions on the clay mineral.     

Graphite oxide intercalation compounds with rotator hexagonal order in the intercalated layers

Graphite oxide intercalation compounds (GOIC), exhibiting a large distance between graphite oxide sheets as well as a long-range order in the organization of guest species, are obtained by intercalation of organic cations containing two long hydrocarbon tails. In particular, graphite oxide layers with interlayer spacing of 0.84 nm, when ionically bonded with cations with two C18 chains, lead to GOIC with interlayer spacing of 3.4 nm and with a hexagonal rotator order in the packing of the long hydrocarbon tails. The intercalation of a second guest species with one or two long hydrocarbon tails not only leads to a further large increase of the interlayer spacing (from 3.4 nm up to 5.8 nm, for guests with C18 alkyl chains) but also, surprisingly, improves the order in the stacking of the layers as well as in the organization of the hydrocarbon chains in the interlayer space. X-ray diffraction measurements on powders and oriented films indicate that these ordered GOIC present intercalate structures with inclined and perpendicular bilayers of guest molecules. Differential scanning calorimetry associated with X-ray diffraction measurements show the occurrence of reversible loss of the hydrocarbon rotator order, which can be associated with significant changes of the interlayer spacing.     

双转子连续混炼机制备插层型聚乙烯/有机蒙脱土纳米复合材料的研究

借助双转子连续混炼机,通过直接熔融插层法制备了聚乙烯/有机蒙脱土纳米复合材料,并用XRD测试了有机蒙脱土的层间距。分析了不同转子转速和喂料速率对聚乙烯有机蒙脱土复合材料层间距及其力学性能的影响。结果表明,选择适当的操作工艺以获得合适的剪切强度对于制备插层型聚乙烯有机蒙脱土纳米复合材料极为重要,当转子转速为400r/min,喂料速率为1.35kg/h时,制得的聚乙烯/有机蒙脱土复合材料层间距最大,插层效果最佳,有机蒙脱土的增强与增韧效果最好。