蒙脱土结构和性质对催化不饱和脂肪酸二聚化反应的影响

钠基蒙脱土经过一次插层有机改性和二次插层有机改性后制得有机改性蒙脱土,作为催化剂用于催化不饱和脂肪酸二聚化反应制备二聚酸。采用XRD、SEM、TEM、FTIR和TG等检测手段对有机改性后蒙脱土的内层结构和性质进行分析。实验表明改性后蒙脱土层间距由1.48nm扩大到3.82nm,而且保持原来的夹心结构不变。蒙脱土的表面形貌和内部结构发生改变,表面变得疏松,内部层间距扩大且插层剂含量增加,分散实验表明二次插层有机改性蒙脱土在不饱和脂肪酸中分散性能优异。相同条件下,二次插层有机改性蒙脱土催化不饱和脂肪酸二聚化反应,二聚酸产率75.33%,是未改性蒙脱土催化制得二聚酸产率的2.14倍,并通过FTIR、1 H NMR和LC-MS证实合成的产物为二聚酸。     

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.     

新型超分散有机蒙脱土的制备和表征

采用十六烷基三甲基溴化铵为插层剂,通过先机械搅拌后超声振荡的复合工艺对钠基蒙脱土进行了有机改性,制备了超分散蒙脱土并对其进行了表征.FTIR表明有机插层剂进入蒙脱土层间;XRD结果表明超分散蒙脱土层间距由改性前的1.01 nm增加到3.13 nm;SEM和TEM表明蒙脱土已被剥离成单个片层.粒径分析表明超分散蒙脱土有很好的亲油性和分散性;沉降对比实验说明超分散蒙脱土分散性好,可长时间悬浮在熔融己内酰胺中.     

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。     

蒙脱土的有机化改性及插层剂的选择

分别利用阳离子表面活性剂十六烷基三甲基氯化铵(CTAC)和阴离子表面活性剂十二烷基磺酸钠(SDS)制备了有机蒙脱土,并通过FTIR和XRD对其结构进行表征,发现CTAC的插层效果明显优于SDS。研究中考察了体系反应温度、pH值对蒙脱土插层效果的影响。结果表明,以CTAC为插层剂,反应时间为1 h,反应温度为80℃,体系pH值为7时,制得的有机蒙脱土其d001值达1.962 nm,层间距最大。     

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.     

新型有机蒙脱土的制备、结构表征及其分散性

采用十二烷基磺酸钠及十六烷基三甲基溴化铵对蒙脱土进行了一次、二次插层改性,红外光谱和X射线衍射表明,两种有机插层剂均已进入蒙脱土的层间,有机蒙脱土的层间距由1.22 nm增加到3.64nm;沉降实验结果表明这种改性蒙脱土在有机介质中表现出很好的分散性.     

改性蒙脱土对PET吹塑瓶阻隔性的影响

在水分散液中使蒙脱土与6－氨基已酸或对氨基苯甲酸进行插层反应制得有机改性蒙脱土。X射线衍射、热重分析和红外光谱测试结果表明，6－氨基已酸或对氨基本甲酸被插层到蒙脱土的晶格片层之间，使层间距增大在双螺杆挤出机中使聚对苯二甲酸乙二酯（PET）与改性蒙脱土进行熔融插层复合得到PET／改性蒙脱土复合材料，并用注－拉－吹工艺成型得到PET／改性蒙脱土复合瓶。阻隔性测试结果显示，PET／改性蒙脱土复合瓶对氧气的阻隔性比纯有明显提高。     

二聚阳离子表面活性剂改性蒙脱土的制备和表征

合成了二聚阳离子表面活性剂GeminiC12,用核磁共振氢谱(1HNMR)表征了它的结构,并用它作为有机插层剂应用于蒙脱土的改性处理。红外光谱(FTIR)、热重分析(TGA)表明,GeminiC12已插层到蒙脱土片层间。X射线粉末衍射(XRD)表明,插层后蒙脱土层间距从1 19nm增加到3 8nm,是十六烷基三甲基溴化铵(CTAB)处理效果的两倍。沉降实验表明,改性后蒙脱土在苯乙烯和石蜡中形成凝胶体系,表现出很好的相容性和分散性,这种改性效果优于目前常用的CTAB处理效果,更有利于聚合物或其单体进入蒙脱土层间形成纳米复合材料。     

有机改性蒙脱土制备聚酰胺6/蒙脱土复合材料

采用有机复合改性的方法制备了改性蒙脱土,并采用原位聚合方法制备了尼龙-6/蒙脱土复合材料,利用FTIR、TG-DTA、XRD对有机蒙脱土进行了表征。结果表明,有机插层剂已进入蒙脱土的层间,使蒙脱土的层间距由原来的1.39 nm增大到2.32 nm,从而改善了它的分散性以及与尼龙-6之间的粘结作用,二者构成的纳米复合材料具有很好的力学性能。当加入2%的有机蒙脱土时,拉伸强度提高16%,冲击强度提高5%。     

DODAC对水热法插层改性蒙脱土结构和性能的影响

选用阳离子表面活性剂双十八烷基二甲基氯化铵(DODAC)作为改性剂,通过水热法插层改性钠基蒙脱土(Na-MMT).采用傅里叶变换红外光谱(FT-IR)、X射线衍射(XRD)、热重分析(TGA)、扫描电镜(SEM)等手段研究了水热插层法和DODAC添加量对有机化蒙脱土结构和性能的影响.研究结果表明:水热法的插层改性效果优于常规插层改性方法,DODAC添加量对有机化蒙脱土的层间结构影响显著,随改性剂添加量增加,有机化蒙脱土的层间距变大,DODAC分子的层间堆叠方式依次由单层、双层向伪三层、类石蜡复合型结构转变.当DODAC添加量为2.0CEC时,水热插层改性效果最为明显.     

抗泥型聚羧酸减水剂的制备及性能

以甲基丙烯酸（MAA）、甲基丙烯酸羟乙酯（HEMA）为单体,过氧化氢（H₂O₂）/抗坏血酸（Vc）为引发剂,甲基烯丙基磺酸钠（SMAS）为链转移剂,合成了一种抗泥型聚羧酸减水剂,通过红外光谱（FTIR）、凝胶渗透色谱（GPC）对聚合物进行结构表征,通过水泥净浆流动度、蒙脱土层间官能团、X射线衍射和吸附量测试,对其分散性能及抑制蒙脱土机理进行了探究。结果显示：合成的抗泥型聚羧酸减水剂在摩尔比为2.5：1时分散性能最佳,当减水剂折固掺量为0.25%时,水泥初始净浆流动度为268mm;与普通聚羧酸减水剂相比,合成的抗泥型减水剂对蒙脱土敏感性较低,与蒙脱土作用后的层间未出现抗泥型减水剂的特征官能团,层间距为1.40nm,抗泥型减水剂在蒙脱土上的吸附量远小于普通减水剂的吸附量。     

蒙脱土负载钴(Ⅱ)-8羟基喹啉的制备及催化性能研究

采用离子交换和配位合成方法,通过配位键将配体引入金属蒙脱土层间,制备了Co(Ⅱ)-8Q/MMT复合催化材料,用IR和XRD分析了催化材料的结构,考察了催化剂催化氧化性能.实验结果表明,层间距增大0.332 nm,表明配体进入金属蒙脱土的片层间;在分子氧的氧化作用下,催化氧化苯乙烯的转化率达到42.3%.     

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.     

Preparation and characterization of poly(ethylene terephthalate) incorporated with secondary-modified montmorillonite

Hexadecyl triphenyl phosphonium bromide montmorillonite (PMMT) was first modified via secondary modification method, and then conjugated with toluene-2,4-diisocyanate (TDI). The as-prepared TDI-PMMT sample was used as a blend polymer in poly(ethylene terephthalate)/TDI-PMMT composite (PET/TDI-PMMT). The chemical properties of original PMMT, TDI-PMMT and PET/TDI-PMMT composite were investigated by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and thermogravimetry analysis (TGA). Results showed that chemical bonds which were formed between TDI and montmorillonite surface provided massive active isocyanate groups in in situ polymerization for the montmorillonite and matrix materials. This structure could have improved the compatibility between PMMT and PET effectively, and allow good distribution of the montmorillonite in polymer matrix. The spacing of montmorillonite layer decreased from 3.72 to 3.28 nm owing to the encapsulation of TDI groups. The physical morphology of nanocomposites was observed through scanning electron microscopy (SEM), transmission electron microscopy (TEM) and XRD, and their thermal performance was evaluated by differential scanning calorimetry (DSC). XRD and SEM studies confirmed that compared to PMMT, the secondary-modified montmorillonite exhibited a better dispersion in PET matrix. TGA and DSC results showed that the thermal stability of PET/TDI-PMMT was superior to PET/PMMT. TEM images of PET/TDI-PMMT indicated that the TDI-PMMT exhibited good dispersion and the TDI-PMMT silicate layers were in better exfoliated state. The interface spacing of all samples was enlarged because of the heating reaction of oligomers. In the meanwhile, the mechanical properties such as tensile strength, flexural strength and flexural modulus of PET/TDI-PMMT were higher than those of PET/PMMT.     

Preparation and investigation of the physical and chemical properties of clay-based polyacrylamide/Cr (III) hydrogels as a water shut-off agent in oil reservoirs

The effects of clay (montmorillonite and kaolinite) in the hydrogels were investigated on various properties such as syneresis and strength of thermal and salinity situations in one of the southern Iranian oil reservoirs. The X-ray diffraction (XRD) patterns exhibited a significant increase in interplanar spacing between the montmorillonite clay layers, varying from the initial value of 12.43 °A to 19.45 °A, which evidences the intercalation formation. It was revealed that even increasing of the interlayer spacing due to kaolinite modification had no effect on the clay compositions. Formation water was used to study the strength of the hydrogel in the presence of ions. The results indicated that 15 wt% increase of kaolinite clay (modified and non-modified) leads to 20% decrease of the hydrogels’ syneresis. The diffusion of polymer chains between the clay layers increased the elastic modulus (G′) of the prepared hydrogels with modified kaolinite and montmorillonite, where the maximum value of G’ was observed in 3 wt% of montmorillonite. Finally, the thermogravimetric analysis (TGA) indicated an increase in the thermal stability of the mentioned hydrogels.     

Preparation and characterization of PVA/OMMT composites

In this study, polyvinyl alcohol/organically modified montmorillonite (HDA/MMT; organoclay) composite was prepared for the intercalation processes. Firstly, the rheological behavior of aqueous montmorillonite dispersions was investigated as a function of solid content. Hexadecylamine (HDA) was added to the montmorillonite dispersion (2%, w/w) in different concentrations in the range of 5 × 10^?4 – 9 × 10^?3 mmol/L. The basal spacing of the organoclay (OMMT) was studied by X‐ray diffraction. The FTIR spectra are obtained from the modified montmorillonite products, which revealed the characteristic absorbencies after treatment with HDA. HDA/MMT/PVA composite, which was produced by the reaction of 1 wt % PVA solution with organoclay complex, is characterized by the rheology, electrokinetic, XRD, FTIR, and SEM techniques. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2315–2323, 2006     

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。     

Synthesis,Characterization, and Microbial Activity of Nanocomposites of Chitosan-Graft-Poly(4-vinyl pyridine) Copolymer/Organophilic Montmorillonite

Organophilic montmorillonite was synthesized by cationic exchange between Na⁺-MMT and N-octyl-N-vinyl-2-pyrrolidonium bromide. Nanocomposites of chitosan grafted with 4-vinyl pyridine and organophilic montmorillonite were prepared in acetic acid using ammonium persulfate as initiator. The molecular structure of the grafted copolymer was confirmed by FTIR. The degree of dispersion and the intercalation spacing of these nanocomposites were investigated using X-ray diffraction. The enhanced thermal stability of nanocomposites was verified by differential scanning calorimetry and thermogravimetric analysis. Preliminary results of the antibacterial and antifungal activities of the prepared nanocomposites have demonstrated significant antimicrobial activity of the nanocomposites compared with pure and grafted chitosan.