天然钙蒙脱土的钠化改型和有机化改性

用碳酸钠作为钠化剂对天然钙蒙脱土进行了钠化改型,用CTAC、CTAB、C18三种插层剂分别对钠蒙脱土进行了有机插层改性。对钠化改型前后的蒙脱土进行了XRD、FTIR分析,对有机改性前后的蒙脱土用XRD、SEM、FTIR和TG-DTA等进行了表征和分析。结果表明:钙蒙脱土经钠化改型后,层间距增大,结晶度变差,活性增强;CTAC、CTAB、C18三种改性剂都能使蒙脱土的晶层间距有较大提高,其中,尤以C18改性剂的有机化效果最为显著;蒙脱土有机改性前后外观变化十分显著;有机改性蒙脱土的结构水无明显变化,层间吸附水显著减少,疏水的有机插层剂主要进入蒙脱土层间,大量脱去层间吸附的水分子,对晶体结构本身并无影响。有机改性后,蒙脱土的吸附水与层间水的脱水温度与脱水量均显著降低,有机插层剂的大量插入,改变了原土的亲水性使之变为疏水,并提高了其热稳定性。     

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.     

机械化学法有机插层改性蒙脱土的研究

采用机械化学法对蒙脱土进行有机插层改性,研究了固含量、反应时间、醇水比、改性剂的加入量、研磨时间等因素的影响。结果表明,在体系固含量为35%、反应时间0.5h、醇水比为1:8、加入1.0CEC的改性剂可使其层间距从钠化后的1.2nm提高到约2.0nm,且片层结构规则;短时间的研磨有利于提高改性蒙脱土的层间有序性,延长时间则会破坏其片层结构。     

硅烷偶联剂复合改性蒙脱土制备NR/OMMT纳米复合材料

采用硅烷偶联剂和十六烷基三甲基溴化铵(CTAB)作为复合改性剂制备有机蒙脱土,使有机蒙脱土的结构发生了改变.其中采用硅烷偶联剂KH570与CTAB复合改性的效果较好,得到了插层效果较好的NR/OMMT纳米复合材料.     

超临界二氧化碳中季鏻盐插层改性蒙脱土的制备

为改善蒙脱土(MMT)的层间结构和表面形貌,采用了几种结构不同的季鏻盐在以超临界二氧化碳(scCO2)为媒介的环境中对钠基MMT进行有机插层改性,考察了改性剂加入量、改性剂种类和共溶剂对插层效果的影响,并采用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)和扫描电镜(SEM)对改性前后的样品进行了分析。结果表明:十四烷基三己基氯化鏻(TTPC)的插层效果较好,当改性剂在反应温度下呈液体状态时能直接对MMT进行插层改性,且当改性剂的阳离子加入量为阳离子交换容量(CEC)的0.4倍时即能取得一定的插层效果,而加入少量共溶剂则能促进改性剂对MMT的插层。     

有机改性蒙脱土对无卤阻燃PC/ABS合金的影响

研究不同有机改性剂对蒙脱土(MMT)的层间距和热稳定性的影响,以及有机蒙脱土复配磷酸酯阻燃剂对聚碳酸酯/丙烯腈-丁二烯-苯乙烯共聚物(PC/ABS)合金的热稳定性和阻燃性能的影响。结果表明,有机改性剂使蒙脱土的层间距变大,热稳定性能满足加工要求。有机改性蒙脱土在基体中的分散性变好,形成插层结构。氮气氛围下,蒙脱土会促进合金的降解,但不影响最终残炭含量。双酚A(二苯基磷酸酯)(BDP)改性蒙脱土使PC/ABS(80/20)合金的第二个热释放峰值分别降为PC/ABS的66%和PC/ABS/FR16的76%。     

载铜蒙脱土对聚氯乙烯阻燃性能的影响

通过离子交换反应将铜离子负载在无机层状蒙脱土上,采用十六烷基三甲基溴化铵对载铜蒙脱土进行有机改性,并将其作为阻燃剂添加到软质聚氯乙烯(PVC)材料中。利用X射线衍射对PVC/有机改性载铜蒙脱土的结构进行表征。结果表明,PVC分子链插层进入有机改性载铜蒙脱土层间形成插层型结构,且蒙脱土的层间距提高到3.69 nm。热重分析、极限氧指数、垂直燃烧和烟密度测试结果表明,有机改性载铜蒙脱土有效改善了PVC的热稳定性,大幅提高了其阻燃性能。有机改性载铜蒙脱土的用量仅为PVC用量的3%时,垂直燃烧即可达到V0级。     

载铜蒙脱土对聚氯乙烯材料阻燃性能的研究

通过离子交换反应将铜离子负载在无机层状蒙脱土上,采用十六烷基三甲基溴化铵对载铜蒙脱土进行有机改性,并将其作为阻燃剂添加到软质聚氯乙烯(PVC)材料中。利用X射线衍射对PVC/有机改性载铜蒙脱土的结构进行表征。结果表明,PVC分子链插层进入有机改性载铜蒙脱土层间形成插层型结构,且蒙脱土的层间距达到3.69 nm。热重分析、极限氧指数、垂直燃烧和烟密度测试结果表明,有机改性载铜蒙脱土有效改善了PVC的热稳定性,大幅提高了其阻燃性能。载铜蒙脱土的用量仅为PVC用量的3 %时,垂直燃烧即可达到V0级。     

季铵盐插层剂对高密度聚乙烯性能的影响

采用季铵盐阳离子作为插层剂与钠基蒙脱土层间的无机阳离子进行离子交换,制备系列有机化蒙脱土,利用红外光谱对蒙脱土的结构进行表征,结果表明,插层剂已进入蒙脱土的层间.同时将有机化蒙脱土与HDPE进行熔融插层,制备了纳米聚乙烯复合材料,研究了插层剂对其部分力学性能的影响.     

PVC-U/蒙脱土复合材料的制备与力学性能研究

采用聚氧乙烯-聚氧丙烯(EP)嵌段共聚物对钠基蒙脱土进行有机化处理改性,XRD测试结果表明嵌段共聚物插层进入了蒙脱土层间.用熔融共混法制备了聚氯乙烯/蒙脱土复合材料,并研究了钠基蒙脱土和EP改性的有机蒙脱土对复合材料力学性能的影响.研究结果表明,采用EP对MMT进行改性能够提高MMT与PVC之间的相容性,PVC-U/MMT-EP复合材料的力学性能得到明显提高,EP对MMT改性是制备有机改性蒙脱土的有效方法之一.     

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.     

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1.48 nm扩大到3.82 nm,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、¹H NMR和LC-MS证实合成的产物为二聚酸。     

Exfoliation of organically modified montmorillonite driven by molecular diffusion in maleated polypropylene

This work is focused on the factors influencing the intercalation of maleated polypropylene (PPMA) into organically modified montmorillonite (OMMT). Two kinds of PPMA were used to explore the optimal candidate for effective intercalation into OMMT. The grafting degree of maleic anhydride and the viscosity of PPMA have effects on the diffusion of polymer molecules. Moreover, the loading level of surfactant was varied to optimize the modification of montmorillonite because the appropriate loading level can provide a balance between interlayer distance and steric hindrance. The kind of surfactant changes the interaction between OMMT and PPMA, and accordingly the intercalation of PPMA is different, resulting in the discrepancy of the intercalation of PPMA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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。     

季铵盐改性蒙脱土的抗菌活性及抗菌机理

采用离子交换法将不同季钱盐插层到钠基蒙脱土中制备了改性蒙脱土.改性蒙脱土对革兰氏阳性菌(S.aereus)和革兰氏阴性菌(E coli)均有很强的抗菌作用,并且随着季铵盐在蒙脱土中的质量分数增加其抗菌活性增强.不同季铵盐改性蒙脱土的抗菌活性不同,其中双季铵盐改性蒙脱土的抗菌活性最好,对S.aereus和E coli的最小抑菌浓度分别为6.25 mg/L和12.5 mg/L.用扫描电镜对与细菌接触不同时间后的改性蒙脱土进行观察,结果表明:细菌先吸附到改性蒙脱土的表面,然后慢慢的变形死亡.同时,对在0.9%的生理盐水中浸泡不同时间后的改性蒙脱土进行X射线衍射和热重分析.结果表明:随着浸泡时间的增加,蒙脱土中的有机物质量分数及层间距均逐渐减少,说明季铵盐能从蒙脱土的层间解吸出来,并进入溶液中直接杀死细菌.因而,改性蒙脱土的抗菌活性是吸附与释放到溶液中的季铵盐离子协同作用的结果.     

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。     

Changes in the morphology of organoclays with HDTMA surfactant loading

The detailed understanding of the interlayer structure of organoclays is of importance in the design of organoclay based materials and their industrial applications. In this study, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been used to provide new insights into the interlayer structure and morphology of HDTMA⁺/montmorillonite organoclays. XRD patterns show that thermal treatment has an important effect on the stability of organoclays, reflected by significant changes in the basal spacing. TEM and SEM micrographs demonstrate that the organoclays with lower surfactant packing density are mainly composed of irregular layer stacking with a number of curved organoclay layers, while those with higher surfactant packing density are mainly composed of regularly intercalated and flat layers. Variations of the interlayer distances exist in all organoclays and are more pronounced in the organoclays with lower surfactant packing density. This study demonstrates that not only the arrangement model of surfactant but also the morphology of organoclay strongly depend on the surfactant packing density within the montmorillonite interlayer space.     

Effect of clay surface modification and organoclay purity on microstructure and thermal properties of poly(l-lactic acid)/vermiculite nanocomposites

Vermiculite (VMT) was successfully modified by cationic exchange of hexadecyltrimethyl ammonium ions, covalent grafting of glycidoxypropyl trimethoxy silane, and combining grafting and intercalation. The complete removal of excess surfactant from VMT resulted in a change in the interlayer structure and higher thermal stability of the organoclay mineral. The organosilane grafted on the clay mineral edges improved the thermal stability of the organoclay mineral. The organoclay minerals were melt compounded with poly(l-lactic acid) (PLLA), and the effect of the nanofiller concentration, type of modification and organoclay mineral purity on the nanostructure and thermal properties of nanocomposites was investigated. The removal of excess surfactant and organosilane functionalization enhanced the dispersion level of the organoclay mineral. PLLA degradation that occurred during nanocomposite processing depended on the clay mineral concentration, the extent of clean surface and the clay mineral dispersion state. The removal of excess surfactant and organosilane functionalization improved the thermal stability of nanocomposites.     

双子阳离子表面活性剂改性蒙脱土的制备与表征

合成了新型双子阳离子表面活性剂Gemini-16,并用其对钠基蒙脱土进行改性。红外光谱(FTIR)、热重(TGA)分析表明,Gemini-16已插层到蒙脱土片层间。X射线衍射(XRD)表明,改性后蒙脱土层间距从1.47 nm增加到3.48 nm。分散性实验表明,经Gemini-16改性的蒙脱土在液体石蜡中表现出很好的相容性和分散性,改性效果优于目前常用的CTAB处理效果,更有利于聚合物单体进入蒙脱土层间形成聚合物/蒙脱土纳米复合材料。     

表面活性剂调控制备钛层柱蒙脱石

以十六烷基三甲基溴化铵(CTAB)为表面活性剂,优化水热合成条件,调控制备了氧化钛层柱蒙脱石材料. 考察了实验过程中反应条件及CTAB用量对钛基蒙脱石层间距的影响,比较了钛基蒙脱石经500℃热处理前后层间纳米TiO2晶粒大小及形态的变化. 结果表明,CTAB对水合钛基柱撑剂在蒙脱石纳米层间域的"生长"过程起到了调控的作用. 应用拉曼光谱和XRD等对所得材料进行了结构分析,讨论了表面活性剂调控钛基柱撑蒙脱石的可能机理,为制备集吸附与光催化降解于一体的新型高效水处理材料提供了新途径.