插层聚合中蒙脱石的有机化研究

用来插层聚合的蒙脱石一般都要经过有机化处理,即用有机阳离子(插层剂)将无机阳离子交换出来,让蒙脱石层间距离得到增大,以便有机分子的进入。蒙脱石的有机化处理一般采用一次插层法,文章采用了一种新的二次插层法对蒙脱石进行有机化处理,并通过XRD、IR、TEM等手段,对一次插层法和二次插层法的效果进行了比较,确定了二次插层法为一种较为理想的蒙脱石有机化方法。     

改性剂及高密度聚乙烯插层和剥离蒙脱石的分子动力学模拟

为研究高密度聚乙烯/有机改性蒙脱石(PE-HD/OMMT)复合材料中改性剂及PE-HD对蒙脱石(MMT)插层和剥离的影响,采用分子动力学方法模拟了OMMT中不同负载量的十八烷基三甲基氯化铵阳离子(OTAC+)在MMT中的排列方式以及对MMT插层的影响.此外,搭建了PE-HD/OMMT复合材料模型,编写MS Perl脚本...     

改性药用蒙脱石载体的制备及表征

对蒙脱石进行钠基化处理,用水溶性阳离子聚合物壳聚糖季铵盐进行表面处理.结果表明,经壳聚糖季铵盐改性处理后的钠基化蒙脱石阳离子交换容量CEC增大至115 mmol/100 g,层间距明显增大至2.206nm.     

表面活性剂在聚合物/蒙脱石纳米复合材料制备中的应用

简要叙述了蒙脱石的结构;综述了阳离子表面活性剂插层蒙脱石以形成有机蒙脱石的机理、插层方法以及阳离子表面活性剂的结构对被插层蒙脱石的层间距的影响;讨论了不同类型的聚合物/蒙脱石纳米复合材料制备方法;同时比较了所得到的纳米复合材料的力学性能、热性能与纯聚合物的力学性能和热性能。结果表明:前者的力学性能和热性能比后者均有较大程度的提高。最后提出了聚合物/蒙脱石纳米复合材料目前存在的问题、发展方向和应用前景等。     

蒙脱石的有机改性工艺及凝胶性能研究

本文采用悬浮液有机改性工艺方法,以季铵盐为有机改性剂,研究了山东某提纯蒙脱石的有机改性工艺条件.研究发现,季铵盐改性剂碳链越长,蒙脱石的层电荷越低,有机改性蒙脱石的凝胶性能越好.其他关键工艺参数为:有机改性剂用量为钠化土阳离子交换容量的1.1～1.3倍,有机改性温度在70～80 ℃,有机改性时间为2.0 h.     

新疆乌兰陵格膨润土的开发及性能表征

以新疆乌兰陵格膨润土为原料,进行了原矿湿法提纯、钙基膨润土钠化改型及钠基膨润土有机化改性用于钻井油基泥浆的研究.结果表明,湿法提纯前钠基膨润土的蒙脱石含量为57.55%;提纯后蒙脱石含量为60.91%.而钙基膨润土蒙脱石含量为56.53%,提纯后蒙脱石含量为59.48%.Na2CO3作为改型剂使钙基土的CEC(阳离子交换容量)提高了26.7%,钠化改型后所制得的有机土的粘度达到0.840Pa·s.季铵盐用量在(8.5～9.0)×10-4mol/g时,D1631有机土的粘度出现了明显的突变点.FTIR表明有机插层剂已进入膨润土的层间.XRD特征峰位移表明膨润土的层间距有明显增加.SEM观察也表明膨润土的层间距增大,层间厚度约为72nm.将有机膨润土应用于钻井油基泥浆中,各项指标均已达到要求,研究表明新疆乌兰陵格膨润土的高附加值开发是可行的.     

蒙脱石的湿法机械球磨剥离

以内蒙古钙基蒙脱石为原料,通过湿法改型、改性制备了钠基蒙脱石和有机蒙脱石.分别以钙基蒙脱石、钠基蒙脱石和有机蒙脱石为对象,在乙醇中湿法机械球磨、超声处理蒙脱石,利用XRD、TEM、AFM等手段研究了机械球磨法对不同层间离子的蒙脱石剥离效果.结果表明,内蒙古钙基蒙脱石湿法钠化及有机化效果良好,机械球磨法剥离钠基蒙脱石效果最佳,剥离型蒙脱石片层尺寸小于200 nm,其平均厚度约为15 nm;有机蒙脱石层间有机物具有稳定蒙脱石片层的作用,有机改性不能促进机械球磨法对蒙脱石片层的剥离.     

新疆夏子街钙基膨润土的高附加值开发

以新疆夏子街钙基膨润土为原料,进行了原矿湿法提纯、钠化改性及钠基土有机化改性及其应用研究.结果表明,湿法提纯前钙基膨润土的蒙脱石含量为91.79%,是一种高品位钙基膨润土,提纯后蒙脱石含量达到95.97%.钠化正交实验结果表明,NaF效果优于传统的钠化剂Na2CO3.在优化条件下钠化改性膨润土的阳离子交换容量(CEC)可达97.5 mmol/100g土,比原矿提高17.25 mmol/100g土.以钠化改性膨润土为原料制得的有机膨润土的粘度达到5.4 Pa*s.FTIR表明有机插层剂已进入膨润土的层间.XRD特征峰位移表明有机膨润土的层间距达到2.143 nm,比钙基膨润土层间距增加0.754 nm.SEM得到的结论与FTIR、XRD表征结果相吻合.将有机膨润土应用于涂料中,其各项检测指标均满足要求.有机膨润土对于金属离子废水的吸附效果优于钙基膨润土.由此可知新疆夏子街钙基膨润土的高附加值开发是可行的.     

阳离子化魔芋葡甘聚糖插层蒙脱石的制备与表征

采用季铵化魔芋葡甘聚糖(CMKGM)对钠基蒙脱石(MMT)进行改性制备有机蒙脱石(CMKGM-MMT),并对改性后的蒙脱石进行红外光谱(FT-IR)和X射线衍射(XRD)等分析表征.结果表明,当制备季铵化魔芋葡甘聚糖改性蒙脱石时,反应条件pH值为4.6、反应温度为60 ℃,且CMKGM的用量是MMT的1.0倍阳离子交换容量时(CMKGM和MMT的质量比为0.9),形成的插层型有机蒙脱石的有机化程度最高,并考察了改性蒙脱石的体外细胞毒性及其对牛血清白蛋白(BSA)的载药性能.     

不同工艺有机插层蛭石的制备及表征

以2倍蛭石阳离子交换容量的十六烷基三甲基溴化铵为插层剂,利用热液搅拌法、球磨法、煮沸法、熔融搅拌法等4种不同工艺对蛭石进行插层处理.对有机插层后的蛭石进行了粉晶X射线衍射、Fourier变换红外光谱和热重分析表征.结果表明:不同插层工艺会导致有机插层蛭石的层间距及微结构的变化.随着层间距的增大,蛭石层间的有机相含量逐渐增大.     

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。     

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.     

Modification of montmorillonite with cationic surfactants. Thermal and chemical analysis including CEC determination

The thermal stability of synthesized and commercial organically modified montmorillonites has been investigated using thermogravimetric analysis (TGA). Four organo-montmorillonites have been prepared by replacing the inorganic cations of a commercial montmorillonite with aliphatic and aromatic ammonium bromide or chloride salts. The modification has been carried out by cation exchange to obtain a high level of intercalation in the montmorillonite. Conformations of the intercalated surfactants have been characterized using Fourier transform infrared spectroscopy (FTIR). Besides fixed organic surfactant, some surfactant in excess still remained in the montmorillonite after repeated washing with water or ethanol/water. The use of a suitable eluent for the surfactants in the washing step was the key issue as shown by the changes of the first degradation peak of Cloisite-Na⁺-hexadecyl benzyl dimethylammonium (CLO-BDHA), Cloisite-Na⁺-benzyl triethylammonium (CLO-BTA) and Cloisite-Na⁺-hexadecyl trimethylammonium (CLO-HTA). Hexadecyl trimethylammonium (HTA) was more sensitive to water and ethanol/water as eluents. Sonication and the use of a polar activator during the modification of montmorillonite increased the amount of surfactant adsorbed by cation exchange. Ammonium acetate method has been revealed as an adequate chemical method to measure the cation exchange capacity (CEC) of inorganic and organic montmorillonites. This method has the advantage with respect to TGA that it does not measure the unfixed surfactant.     

直接熔融复合制备聚酰胺6／未改性蒙脱土纳米复合材料

在普通双螺杆挤出机上，基于未改性蒙脱土和聚酰胺6的直接熔融复合制备了纳米复合材料。通过插层剂的合理选择及不同插层剂的复配使用，可以得到具有插层刷离分散形态的聚酰胺6／未改性蒙脱土纳米复合材料。力学性能测试结果表明，有可能通过在聚酰胺6／未改性蒙脱土复合体系中插层剂的选择与调配实现同时增加聚酰胺6基体的强度和韧性的目的。在特定的插层剂复配条件下，复合材料的弯曲强度较基体增加20％，弯曲模量增加29％，同时干态冲击强度的增幅达70％以上。此外，还讨论了聚酰胺6／未改性蒙脱土复合体系的动态力学行为和流变性能。     

Modification of montmorillonites with thermally stable phosphonium cations and comparison with alkylammonium montmorillonites

Alkylammonium montmorillonites have onset temperature of degradation in the same temperature range used for compounding of thermoplastics, thus, requiring more thermally stable organic cations. In the current study, phosphonium, imidazolium and pyridinium ions differing in their chemical architecture (length of alkyl chains, number of phenyl groups etc.) were exchanged on the surface of montmorillonites. The montmorillonites with two different cation exchange capacities (CECs) were used. The thermal behavior of the modified montmorillonites was analyzed by thermogravimetric analysis. To achieve quantitative insights into the onset of degradation, temperatures to reach 5% and 10% mass loss and peak degradation temperatures were compared. Time to reach 1% mass loss was also calculated in the dynamic TGA. The surfactants used in the study were more thermally stable than the conventional alkylammonium cations due to their delayed onset as well as peak degradation temperatures. The time required to attain certain extent of degradation was also much higher in the case of phosphonium montmorillonites, thus, confirming their better thermal resistance. Though the degradation temperatures as well as profiles of the modified montmorillonites with different CECs were similar, the dynamic TGA revealed better thermal behavior of the higher CEC montmorillonite. The X-ray diffraction studies also concluded that optimal modification of the montmorillonite surface could be attained, thus, confirming the high potential of phosphonium montmorillonites for nanocomposites.     

Influence of ethanol addition on the modification of montmorillonite by hexadecyl trimethylammonium bromide

Although modification of montmorillonite (MMT) with cationic surfactants has been studied extensively, the influence of the reaction medium has not been investigated systematically. The present paper reports the influence of ethanol on the modification of MMT using hexadecyl trimethylammonium bromide (HDTMA-Br). Wide angle X-ray diffraction (WAXD) and thermogravimetric analysis (TGA) were used to characterize the organically modified montmorillonite (OMMT). The addition of ethanol had little influence on the cation exchange, but affected greatly on the intercalation of the surfactant ion pairs into the interlayer space when HDTMA exceed the cation exchange capacity (CEC) of MMT. The increase of the ethanol/water ratio increased the critical micelle concentration (CMC) of HDTMA-Br solution. The intercalation of HDTMA ion pairs proceeded when the HDTMA concentration was above the CMC. It was confirmed that both of basal spacing and organic fraction followed sigmoid functions for OMMT prepared with excess HDTMA-Br amount and various surfactant concentrations under different CMC.     

功能化聚乙烯蜡／有机蒙脱土插层复合母粒的研制

用两种不同改性剂与蒙脱土进行离子交换制得了两种有机蒙脱土，用功能化聚乙烯与有机蒙脱土进行熔融插层复合制备了功能化聚乙烯蜡/有机蒙脱土插层复合母粒，用X-射线衍射，傅立叶红外光谱，热重分析，差示扫描量热和抽提实验等对所得有机蒙脱土和功能化聚乙烯蜡/有机蒙脱土插层复合母粒的结构与性能进行表征。结果表明，有机蒙脱土层间距的增大和功能化聚乙烯蜡的极性活性官能团使得功能化聚乙烯蜡可以被插入到有机蒙脱土的夹层之间，甚至与层间的有机改性剂形成共价键而不被有机溶剂抽提出来。     

Effect of melt processing conditions on mechanical properties of polyvinylchloride/organoclay nanocomposites

Abstract

Polyvinylchloride compositions have been prepared by the melt intercalation method using a single screw extruder. Different types of nanofiller based on natural sodium montmorillonite were tested. In particular, intercalating agents containing amine groups combined with co-intercalating agent (low or high molecular weight plasticiser) were examined to determine which is the most suitable not only for producing the largest basal spacing and subsequently the best exfoliation of clay tactoids in polymer matrix, but also for the highest beneficial influence on mechanical properties. In the case of improved exfoliation, the effect of compounding was investigated. Therefore, three values of screw speed were studied and some blends were compounded twice to study the retention time in a single screw extruder and the influence on orientation, dispersion and exfoliation of clay particles in the PVC matrix. Moreover, the effect of different types of plasticiser on mechanical properties was also studied. Bis(2-ethylhexyl) phthalate, Bis(2-ethylhexyl) adipate and Lankroflex epoxy plasticiser were tested. Dynamical thermo-mechanical properties were examined and the tensile properties of thin PVC sheets prepared by calendaring. Using X-ray diffraction and transmission electron microscopy, it was found that partially intercalated and disordered structures arose in polyvinylchloride composites containing sodium montmorillonite, while a fine dispersion of partial exfoliation of individual montmorillonite layers in polyvinylchloride matrix was observed when this clay was organically modified. Finally, the value of the tensile modulus for PVC nanocomposites containing as little as 5 wt-% montmorillonite was increased three times provided that the optimum melt processing conditions were used.     

Cu~(2+)-膨润土的制备、结构及性能研究

研究了天然膨润土的提纯,钠化改型及Cu2+-膨润土的制备,比较了不同的钠化剂对钠化土的蒙脱石含量,离子交换容量的影响。结果表明,天然膨润土提纯后蒙脱石的含量增加;采用焦磷酸钠为钠化剂进行溶液交换的钠化效果最佳;悬浮体系酸、碱浓度适中时(pH=4~11),Cu2+-膨润土表现出对酸、碱的缓冲作用,pH值保持在4.76左右。