马来酸酐改性蛭石的制备及表征英文张尧

硅酸盐学报· 850 ·2008年马来酸酐改性蛭石的制备及表征张尧1，韩炜1,2，李秋影1，吴驰飞1(1. 华东理工大学材料科学与工程学院，高分子合金研究室，上海 200237；2. 长江水利委员会长江科学院，武汉 430010)摘要：以有机小分子马来酸酐作为改性剂，利用球磨法在不同溶剂中对蛭石进行有机改性。

对有机改性的蛭石进行了X射线粉晶衍射、Fourier变换红外光谱仪和热重分析表征。

结果表明：在水溶液条件下，球磨能够使蛭石片层被马来酸酐分子剥离，蛭石的(001)面特征衍射峰消失。

在有机溶剂中球磨，蛭石不能够被马来酸酐剥离。

讨论了马来酸酐改性蛭石的机理。

研究了球磨时间对马来酸酐改性蛭石的影响。

关键词：蛭石；剥离；马来酸酐；改性机理；球磨中图分类号：P578.963；TB383 文献标识码：A 文章编号：0454–5648(2008)06–0850–04CHARACTERIZATION OF VERMICULITE MODIFIED BY MALEIC ANHYDRIDEZHANG Yao1，HAN Wei1,2，LI Qiuying1，WU Chifei1(1. Polymer Alloy Laboratory, School of Materials Science and Engineering, East China University of Science and Technology,Shanghai 200237; 2. Changjang River Scientific Research Institute, Wuhan 430010, China)Abstract: Vermiculite was modified by maleic anhydride through ball milling in different solvents. The microstructures and proper-ties of modified vermiculite were characterized by X-ray diffraction, Fourier infrared spectroscopy and thermal gravimetric analysis. Results indicate the vermiculite layer can be exfoliated by maleic anhydride only in water, and the characteristic diffraction peak of vermiculite disappears. However, the vermiculite layer cannot be exfoliated by maleic anhydride in organic solvent. The mechanism of vermiculite modification by maleic anhydride is discussed. The influence of ball milling time on modified vermiculite was investi-gated.Key words: vermiculite; exfoliated; maleic anhydride; modified mechanism; ball millingVermiculite is a layered silicate. Each layer of ver-miculite is made of two silicon-oxygen tetrahedrons and one magnesium-oxygen octahedron. The crystal structure of vermiculite and montmorillonite are quite similar, be-cause they both belong to the montmorillonite-vermiculite group of layered silicates. Based on the analysis of their mineralogical origin, vermiculite seems to be the inter-mediate product of phlogopite-biotite and montmorillo-nite. Compared with montmorillonite, vermiculite has many advantages, such as better crystallographic form, stability, cation interchangeability, temperature retention, light weight, frost resistance, antibiosis, and abundant sources.[1–5] But it is quite difficult to exchange cations with organic molecules because of its high interlayer charge density. Little has been reported about studies on intercalation of vermiculite.[6–8] Because these galleries of layered silicate are generally occupied by metallic cations such as K+, Na+, Ca2+, and Mg2+, usually, layered silicates are modified by exchanging the organic ammonium salts to form organoclays.[9] However, organic ammonium salts are only compatible with polymer matrixes without any chemical reaction. Therefore, in polymer/layer sili-cate nanocomposites prepared by these organoclays, la- yered silicate usually cannot be exfoliated, especially in polyolefine matrixes, and sometimes the mechanical properties of the prepared nanocomposites are even de-creased.[10] So besides the conventional ion exchanged method, research about modified clay prepared with new organic small molecules that have better compatibility or even can react with polymer matrix has become very important and significant.As far as we know, there have been no reports on the收稿日期：2007–07–04。

修改稿收到日期：2008–03–23。

基金项目：长江科学院中央级公益性科研院所基本科研业务费(YWF0729/CL02)资助项目。

第一作者：张尧(1982—)，男，博士研究生。

通讯作者：吴驰飞(1960—)，男，博士，教授。

Received date:2007–07–04. Approved date: 2008–03–23.First author: ZHANG Y ao (1982–), male, postgraduate student for doctor degree. E-mail: ninanzy@Correspondent author: WU Chifei (1960–), male, Doctor, professor.E-mail: wucf@第36卷第6期2008年6月硅酸盐学报JOURNAL OF THE CHINESE CERAMIC SOCIETYVol. 36，No. 6J u n e，2008张尧等：马来酸酐改性蛭石的制备及表征· 851 ·第36卷第6期modification of vermiculite with non-organic cations. As a continuation of our work on vermiculite modification and polymer/vermiculite nanocomposites,[11–13] we used maleic anhydride (MA) as a modification agent in the ball milling method to prepare organic vermiculite. The effect of preparation conditions such as solvent and ball milling time on the structure of organic vermiculite was studied and the mechanism of the exfoliation of organic vermiculite by MA was discussed.We use MA as modified agent through ball milling method to preparing organic vermiculite (OVMT). The effect of preparing conditions such as solvent, ball mil- ling time to the structure of OVMT was studied and the mechanism of the exfoliated of OVMT by MA was dis-cussed.1 Experiment1.1 Materials and preparation of organic ver-miculiteVermiculite (VMT) with a cation exchange capacity (CEC) value of 98.6mmol/100g was supplied by the Dongping Mining Structural Materials Plant, Shijiaz-huang, China. The composition (in mass, the same below) of the vermiculite was SiO2 41.3%, Al2O3 11.7%, MgO 25.2%, CaO 1.3%, FeO 1.5%, Fe2O3 3.4%, TiO2 1.3%, K2O 6.0%, P2O5 0.1%, H2O 3%, Na2O 1.9%, MnO 0.04%, TiO 5.0%, and burn loss 6.6%. The vermiculite was comminuted in an airflow shatter machine (model QS50, China), purified by sedimentation, dried, shattered and sifted through a 200mesh (<75µm) filter before use. Maleic anhydride, acetic acid and acetone were used as received without further purification.Organic vermiculite was prepared as follows: first, 5g MA was dissolved in 200mL different solvents (deio- nized water, acetic acid and acetone), and then 5g VMT with the above solution were milled by a ball mill (model QM–ISP 2, China) with different time. The rotation speed was 450 r/min. After milling, the compound was washed with deionized water several times, dried in a vacuum oven at 100℃, shattered and sifted out to provide sam-ples.1.2 CharacterizationX-ray diffraction (XRD) measurement was carried out on a diffractometer (Rigaku D/max, Japan) using Cu Kαradiation with a generator voltage of 40kV and a current of 200mA. The diffractogram was scanned in the 2θrange from 1.2° to 40° at a rate of 2°/min. Fourier transform infrared spectroscopy (FTIR) was carried out with a Nicolet 5SXC spectrometer on a KBr Matrix.The thermogravimetric (TG) measurements were taken si-multaneously with a thermal analysis SDTQ600 instru-ment in the temperature range from 20℃ to 1000℃under nitrogen. The rate of heating was 10℃/min. 2 Results and discussion2.1 XRD analysis of OVMT prepared in differentsolventsFigure 1 shows the XRD patterns of VMT and OVMT. The XRD patterns of OVMT samples prepared in diffe- rent solvents are very different. The characteristic peak of d(001) of the VMT appears at 5.9°, corresponding to a basal spacing of 1.48nm. The peak at 2θ=7°–9° corre-sponds to a mica group mineral. The sample of VMT is a vermiculite-hydrobiotite interstratification mineral.[14] In the XRD pattern of the OVMT sample prepared in deio- nized water (VMT–MA–water, 2h), the d(001) of VMT disappears. But in the XRD patterns of the OVMT sam-ples prepared in acetone (VMT–MA–acetone, 2h) and in acetic acid (VMT–MA–acid, 2h), the d(001) of VMT still exists. The disappearance of the d(001) of VMT indicates that the order structure of the VMT layer has been de-stroyed. The MA can interact with the VMT layer by the ball milling method in deionized water, so MA can cause the VMT layer to be exfoliated and dispersed. In two typical organic solvents of acetic acid and acetone, the interaction of MA and the VMT layer is minimal, so the structure of the VMT layer does not change, indicating that the solvent has a very important influence on the preparation of OVMT.Fig.1 XRD patterns of VMT and OVMT samples2.2 Mechanism of OVMT modified by MABased on the above results, the formation mechanism of OVMT is shown in Fig.2. It is well known[15–18] that pristine clay is hydrophilic and can form a stable suspen-sion in water, in which clay is dispersed as isolated sheets or small domains consisting of a few sheets. So in the experimentation with OVMT prepared in water, the VMT layer is dispersed as isolated sheets or small domains consisting of a few sheets and MA molecules are dissolved硅 酸 盐 学 报· 852 ·2008年Fig.2 Schematic representation of clay modificationin water, as shown in Fig.2. MA molecules and the VMT layer can interact with each other by ball milling. When the water is vaporized, if MA is absent, the VMT layer will agglomerate together again by electrostatic interac-tion. Because of the interaction of MA and the VMT layer, the order structure of the VMT layer is destroyed. The VMT layer is exfoliated and dispersed by MA.However, in organic solvent, the VMT layered clay cannot be dispersed as isolated sheets or small domains consisting of a few sheets. So, the MA molecules cannot react with VMT layers in organic solvent.2.3 FTIR analysis of organic vermiculite pre-pared in different solventsThe FTIR patterns of VMT and OVMT samples pre-pared in deionized water by ball milling for 2 h (MA– VMT–water, 2 h) are shown in Fig.3. In VMT, the 3 430 cm –1 peak is due to the —OH stretching vibration of the adsorption water, and the 1 640 cm –1 peak is due to the —OH deformation vibration of the adsorption water. The 1 001 cm –1 peak is attributed to the Si —O stretching vi-bration of VMT. Compared with VMT, three new peaks appear in the pattern of OVMT (MA–VMT–water, 2 h). The 2 920 cm –1 and 2 850 cm –1 peaks are due to the al-kane —CH stretching vibration. The characteristic peak at 1 700 cm –1 is due to the C =O vibration. These new peaks indicate the presence of MA and the interaction ofMA and the VMT layer.Fig.3 FTIR spectra of VMT and OVMT samples2.4 TG analysis of OVMT prepared in differentsolventsFigure 4 shows the TG curves of VMT and OVMT samples prepared in deionized water by ball milling for 2 h (MA–VMT–water, 2 h). The mass loss at 20–160 ℃ is due to the evaporation of interlayer water and adsorption water in VMT and the mass loss after 500 ℃ is due to the dehydroxylation of VMT. In contrast with VMT, a new mass loss appears at 160–500 ℃ in the pattern of OVMT (VMT–MA–Water, 2 h), which is caused by the mass loss of organic molecules. The mass loss at 160–500 ℃ is calculated to be little, only 4.11%, indi-cating a little MA can cause VMT layer exfoliation.Fig.4 TG curves of VMT and OVMT samples2.5 Influence of ball milling time on OVMTFigure 5 shows the XRD patterns of OVMT prepared in deionized water for different ball milling time. The d (001) of VMT become weak but still exist in the XRD patterns of OVMT when the ball milling time is less than2 h, and the peaks at 2θ=7°–9° become strong. This may be because a part of K +in the vermiculite- hydrobio- tite interstratification mineral is dissolved out by MA, and the bivalent cations in the VMT layer exchange with this K +, so the layer space decreases from 1.4 nm to 1.0 nm, and the layer structure of VMT changes张尧等：马来酸酐改性蛭石的制备及表征· 853 ·第36卷第6期Fig.5 XRD patterns of vermiculite and organic vermiculites to hydrobiotite.When the ball milling time is longer than two hours, the d(001) of VMT disappear with the increase of ball milling time, and simultaneously, the peaks at 2θ=7°–9° become weak. This phenomenon may be because the unstable hydrobiotite structure can be de-stroyed by the strong machine force.3 Conclusions(1) MA can be used to modify VMT by the ball mil- ling method in water; the layer of VMT is exfoliated by MA.(2) The layer of VMT cannot be exfoliated by MA in organic solvents such as acetic acid and acetone.(3) The increase of ball milling time is beneficial for the further exfoliation of the VMT layer.References:[1] WANG Pu, PAN Zhaolu, WENG Lingbao, et a1. Systematic Mineral-ogy (second volume) [M] (in Chinese). Beijing: Geological Press, 1984: 464–466.[2] LI Minhua, CHEN Yuhua. The application status and developmentprospects of vermiculite in non-traditional areas [J]. Non-Met Min (in Chinese), 1989 (5): 33–40.[3] JOHN A. Vermiculite: a review of the mineralogy and health effects ofverminculite exploitation [J]. Regul Toxicol Pharm, 1995, 21: 397– 405.[4] WANG Jingliang. The application prospect of vermiculite [J]. 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