Fe Montmorillonite Research Articles

Experimental and Modeling Studies on Sorption Behaviour of 133Ba(II) on Fe–Montmorillonite Clay Minerals

Fe type clay minerals, Fe–montmorillonite, are expected to form in the nuclear waste repositories over a span of few years owing to the interaction of corrosion products from overpack and/or canister with bentonite consisting of montmorillonite (Mt) as the major clay mineral. Therefore, it is important to understand the properties of altered clay minerals, Fe–Mt. In the present study, the sorption behaviour of 133Ba(II), one of the high-yield fission products of uranium-based fuels and analogue of 90Sr (t1/2 = 28.5 y), on Fe(II)–Mt and Fe(III)–Mt has been investigated. Retention behavior of Ba(II) on Fe–Mt has been studied at varying pH (3–9), ionic strength (0.001 M–1 M) and Ba(II) concentration (10−9–10−3 M) by batch sorption method. The distribution coefficient (Kd) of Ba(II) on Fe–Mt was found to be nearly independent of pH while it decreased with increasing ionic strength indicating ion exchange as the dominant Ba(II) sorption mode on Fe–Mt. Adsorption isotherm of Ba(II) exhibited linearity in the entire Ba(II) concentration range. A comparison of Ba(II) sorption behavior on Fe–Mt and Na–Mt has been made. The Fe released from both Fe(III)–Mt and Fe(II)–Mt was measured in all the sorption experiments and was found to be much less in the case of Fe(III)–Mt (≤ 1.7 ppm) when compared to Fe(II)–Mt (~ 25 ppm). The modeling of Ba(II) sorption profiles on Fe–Mt and Na–Mt has been carried out using FITEQL 4.0.

Flammability properties of intumescent flame retardant polylactic acid/layered silicate nanocomposites

Novel intumescent flame retardant polylactic acid (PLA) composites containing different melamine polyphosphate (MPP)/pentaerythritol (PER) and organicmodified montmorillonite (OMT) formulations have been prepared and studied. The synthetic Fe-montmorillonite (Fe-MMT) and natural Na-montmorillonite (Na-MMT) are chosen and modified by hexadecyltrimethylammonium bromide (CTAB). The flammability properties of PLA composites are investigated by UL-94 tests, limited oxygen index (LOI) and microscale combustion calorimetry (MCC) experiments. It’s found that the incorporation of organically modified layered silicate can further improve the flame retardancy of PLA composites, and Fe-OMT is more effective than Na-OMT. In addition, the effect of OMT on thermal degradation stability of PLA composites is analyzed using thermogravimetric analysis (TGA). The results show the addition of Fe-OMT decreases the onset decomposition temperature, but remarkably increases the char residue.

Sorption of Eu(III) on Fe–montmorillonite relevant to geological disposal of HLW

Abstract Montmorillonite (Mt) is the major clay mineral of bentonite, which is the candidate buffer material in the engineered barrier system for geological disposal of high level waste (HLW). The alteration of Mt due to its interaction with carbon steel (overpack) can produce Fe–Mt. In order to understand the basic properties of Fe–Mt, the sorption studies using Eu(III) are reported here. For this, Fe(III)–Mt was prepared by conventional cation exchange method using FeCl3 with Na–Mt. The obtained Fe(III)–Mt was then reduced to Fe(II)–Mt using ascorbic acid. Both the samples were characterized based on their X-ray diffraction, Fourier transform infrared spectra, cation exchange capacity and specific surface area. The batch sorption studies of Eu(III) were conducted for both Fe(III)–Mt and Fe(II)–Mt as a function of pH (3–10), ionic strength (0.001 M–1 M) and Eu(III) concentration (10−8–10−3 M). The distribution coefficient (Kd) was found to be higher for Fe(III)–Mt compared to Fe(II)–Mt and Na–Mt. The sudden increase in sorption in the pH range 4.5–6 and remaining constant beyond it indicates ion exchange mechanism at pH<4.5, with surface complexation mechanism dominating the sorption at pH>4.5. This is further corroborated by ionic strength dependent sorption data which shows decrease in sorption capacity of Fe–Mt with increasing ionic strength at low pH, but remaining more or less unchanged at higher pH. Eu(III) adsorption isotherm on Fe–Mt increased linearly with [Eu(III)] reaching saturation at 10−5 M and 10−4 M for Fe(III)–Mt and Fe(II)–Mt, respectively. The amount of iron released from Fe–Mt and Fe(II)/Fetotal during sorption were estimated to understand the effect on Eu(III) sorption behaviour by release of interlayer iron in Fe–Mt.

Green synthesis of a bifunctional Fe–montmorillonite composite during the Fenton degradation process and its enhanced adsorption and heterogeneous photo-Fenton catalytic properties

A novel Fe–MMT-I composite was synthesized during the degradation of rhodamine B (RhB) through Fenton's method, which could degrade RhB, reuse iron sludge and obtain high efficient bifunctional composite at the same time.

Improved flame-retardant properties of HIPS/ATH system by organo Fe-montmorillonite

High-impact polystyrene nanocomposites (HIPS) with aluminium trihydroxide (ATH) and organo-modified Fe-montmorillonite (Fe-OMT) were prepared by melting intercalation. The nanocomposite structures were characterized by X-ray diffraction and transmission electron microscopy. The results show that the intercalated and exfoliated nanocomposites were formed. Accordingly, the thermal stability and flame-retardant properties were evaluated by thermogravimetric analysis, limiting oxygen index, UL94 and the cone calorimeter test. The results indicated that the nanocomposites had excellent thermal stability and the char yield was also improved. When 4 wt% organo-modified Fe-MMT was added in the HIPS/ATH (46 wt%) composites, the nanocomposites were able to achieve UL94 V-0 grade. The heat release rate, total heat release, and mass loss rate of the nanocomposites were reduced. Furthermore, the addition of Fe-OMT could further improve the smoke suppression property of HIPS composites. The improved flame-retardancy caused by Fe-OMT in the HIPS/ATH matrix maybe due to a reinforced char layer which prevents the diffusion of the oxygen and decomposed organic volatiles in the flame during combustion.

Improved flame-retardant properties of HIPS/ATH system by organo Fe-montmorillonite

High-impact polystyrene nanocomposites (HIPS) with aluminium trihydroxide (ATH) and organo-modified Fe-montmorillonite (Fe-OMT) were prepared by melting intercalation. The nanocomposite structures were characterized by X-ray diffraction and transmission electron microscopy. The results show that the intercalated and exfoliated nanocomposites were formed. Accordingly, the thermal stability and flame-retardant properties were evaluated by thermogravimetric analysis, limiting oxygen index, UL94 and the cone calorimeter test. The results indicated that the nanocomposites had excellent thermal stability and the char yield was also improved. When 4 wt% organo-modified Fe-MMT was added in the HIPS/ATH (46 wt%) composites, the nanocomposites were able to achieve UL94 V-0 grade. The heat release rate, total heat release, and mass loss rate of the nanocomposites were reduced. Furthermore, the addition of Fe-OMT could further improve the smoke suppression property of HIPS composites. The improved flame-retardancy caused by Fe-OMT in the HIPS/ATH matrix maybe due to a reinforced char layer which prevents the diffusion of the oxygen and decomposed organic volatiles in the flame during combustion.

Efficiency of Fe–montmorillonite on the removal of Rhodamine B and hexavalent chromium from aqueous solution

Fe–montmorillonite (Fe–Mt) was prepared and tested for its potential application in the simultaneous removal of hexavalent chromium (Cr(VI)) and rhodamine B (RhB) from aqueous solution. The adsorption kinetics and capacities of Fe–Mt toward Cr(VI) and RhB were determined in relation to the initial contaminant concentration, pH of the solution and concentration of coexist contaminant. The adsorption kinetics of Cr(VI) or/and RhB in both single and simultaneous systems were investigated, which showed that an equilibrium time of a few hours was needed for the adsorption of Cr(VI) and RhB on Fe–Mt. The pseudo-second order model offers a better fit than pseudo-first order model for the Cr(VI) and RhB adsorption. Compared with the single adsorption systems, adsorption rates and quantities of Cr(VI) and RhB adsorbed on Fe–Mt were slightly enhanced in the simultaneous adsorption system. The most effective pH range for the removal of Cr(VI) and RhB was found to be 3.0–4.0. Cr(VI) adsorption isotherms were best represented by the two-site Langmuir model while RhB isotherms followed the Freundlich model. For both contaminants, the adsorption of one contaminant increases with increase in the initial concentration of the other one. Therefore, Fe–Mt could simultaneously remove Cr(VI) and RhB from water. The properties of Fe–Mt were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TG). The findings of this study provide novel information for the development of clay-based adsorbents toward dyes and heavy metals.

Thermal and combustion behavior of ethylene‐vinyl acetate/aluminum trihydroxide/Fe‐montmorillonite composites

AbstractThe flammability characterization and synergistic flame‐retardant effect of Fe‐montmorillonite (Fe‐OMT) in the ethylene‐vinyl acetate/aluminum hydroxide (EVA/ATH) compounds were studied using limiting oxygen index (LOI), UL‐94 test, cone calorimeter, microscale combustion calorimetry (MCC), and thermogravimetric analysis (TGA). The results showed that addition of Fe‐OMT increases the LOI value and improves the UL 94 rating. Cone calorimeter data indicate that the addition of Fe‐OMT greatly reduced the heat release rate and carbon monoxide production rate. Furthermore a compact char residue formed on the surface of the sample with a suitable of Fe‐OMT during the combustion. The MCC results indicate that addition of Fe‐OMT reduced the heat release rate and catalyzed the decomposition of EVA. The TGA data showed further evidence that Fe‐OMT can catalyze carbonization reactions. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

Kinetics of thermo-oxidative degradation of polypropylene/aluminum trihydroxide/organo Fe-montmorillonite nanocomposites

In the article, the thermal oxidative degradation kinetics of pure polypropylene/aluminum trihydroxide (PP/ATH) and PP/ATH/organo Fe-montmorillonite (Fe-OMT) nanocomposites were investigated using Kissinger, Friedman and Flynn–Wall–Ozawa methods. The results showed that thermal oxidative degradation of PP/ATH/Fe-OMT nanocomposites to PP/ATH were complex reaction: the whole process of thermal oxidative degradation were composed with the decomposition of ATH, the cracking and charring of the backbone chains of PP, and the oxidative degradation of char, which the curses of energy mutative with the process of thermal oxidative degradation. The control steps were different in each degradation stage. The activation energy was high in the original degradation stage. It was due to the molecular structure and may closely relate with onset temperature. In the intermediate process, the activation energy was low. In the last stage of the degradation, the activation energy was graveled because the carbon may be oxidized. In the whole process of thermal oxidative degradation, the activation energy of PP/ATH/Fe-OMT nanocomposite was higher than that of PP/ATH.

Catalytic activity of choline modified Fe(III) montmorillonite

A series of mixed-cation organoclays, containing both Fe 3+ and choline + cations, were prepared using montmorillonite and tested for catalytic activity in three Fe 3+-mediated reactions: the oxidative coupling of 2-naphthol, coupling of anthrone and a Lewis-acid catalysed indole conjugate addition. Clays with different Fe 3+:choline + ratios were required to achieve maximum catalytic activity in each reaction. For coupling of both 2-naphthol and anthrone, the most effective catalysts, as measured by the turnover frequency (TOF), were mixed Fe 3+/choline + clays of varying ratios, but the catalytic efficiency of Fe 3+ montmorillonite in the conjugate addition of indole with methyl vinyl ketone decreased with the addition of choline +. This result could potentially be explained by the effect of choline + decreasing the accessibility of Lewis acid domains. The results of this study provide proof that it is possible to tune mixed-cation clays with maximum catalytic activity in specific reaction types for specific substrates. Such mixed-cation organoclays offer advantages over traditional clay-based sorbents in environmental remediation applications, as they have the potential to bind organic contaminants selectively, via interaction with surface-exchanged organic cations, and neutralise organic molecules through catalytic exchange cations that are also present on the clay surface.

Decolorization of Acid Red 1 dye solution by Fenton-like process using Fe–Montmorillonite K10 catalyst

In this work, the decolorization of Acid Red 1 (AR1) dye was conducted using Fe(III) oxide immobilized on Montmorillonite K10 (Fe–MK10) catalyst in the presence of hydrogen peroxide (H 2O 2) in batch process. The effects of different parameters such as iron loading (Fe 3+) on Montmorillonite K10 (MK10), catalyst dosage, solution pH, initial concentration of H 2O 2 and AR1 and reaction temperature on the decolorization efficiency of the process were studied. The results indicated that by using 5.0 g L −1 catalyst dosage of 0.14 wt.% Fe–MK10 at pH 2.5 and 16 mM of H 2O 2, 99% of the 50 mg L −1 of AR1 was decolorized within 150 min. Leaching test indicated that the leached iron from the catalyst was less than 5 mg L −1.

Influences of organic-modified Fe-montmorillonite on structure, morphology and properties of polyacrylonitrile nanocomposite fibers

The Fe-montmorillonite (Fe-MMT) combined catalysis effects of Fe ion with barrier effects of silicate clays, was firstly synthesized by hydrothermal method, and then was modified by cetyltrimethyl ammonium bromide (CTAB). The organic-modified Fe-montmorillonite (Fe-OMT) was dispersed in the N, N-dimethyl formamide (DMF) and then compounded with polyacrylonitrile (PAN) solution which was dissolved in DMF. The composite solutions were electrospun to form PAN/Fe-OMT nanocomposite fibers. The influences of the Fe-OMT on the structure, morphology, thermal, flammability and mechanical properties of PAN nanocomposite fibers were respectively characterized by X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM), Scanning electron microscopy (SEM), Thermogravimetric analyses (TGA), Micro Combustion Calorimeter (MCC) and Electronic Single Yarn Strength Tester. It was found from XRD curves that there was not observable diffraction peak of silicate clay, indicating that the silicate clay layers were well dispersed within the PAN nanofibers. The HRTEM image indicated that the multilayer stacks of nanoclays could be found within the nanofibers and were aligned almost along the axis of the nanofibers. The SEM images showed that the diameters of nanocomposite fibers were decreased with the loading of the Fe-OMT. The TGA analyses revealed that the onset temperature of thermal degradation and charred residue at 700°C of PAN nanocomposite fibers were notably increased compared with the pure PAN nanofibers, contributing to the improved thermal stability properties. It was also observed from MCC analyses that the decreased peak of heat release rate (PHRR) of the PAN nanocomposite fibers reduced the flammability properties. The loadings of Fe-OMT increased the tensile strength of PAN nanocomposite fibers, but the elongation at break of PAN nanocomposite fibers was lower than that of the PAN nanofibers.

Partial Exchange of Fe(III) Montmorillonite with Hexadecyltrimethylammonium Cation Increases Catalytic Activity for Hydrophobic Substrates

Fe(III) montmorillonite clay that was partially exchanged with hexadecyltrimethylammonium (HDTMA(+)) cations achieved increased catalytic activity for the oxidative coupling of hydrophobic organic substrates. A series of mixed-cation organoclays were produced, where the organic cation content ranged from 6 to 50% relative to the cation-exchange capacity (CEC) of the clay, and were tested for catalytic activity using different Fe(III)-mediated oxidative coupling reactions. Enhanced catalytic activity by Fe(3+)/HDTMA(+) montmorillonite for coupling hydrophobic substrates was observed, with maximum catalytic activity in the oxidative coupling of 2-naphthol observed at 6% HDTMA(+) coverage. However, maximum catalytic activity with a more hydrophobic substrate, anthrone, was achieved with 50% HDTMA(+) coverage, indicating that matching levels of organic modification to substrate hydrophobicity improves catalytic activity. The organization of the organic cations at the clay surfaces proved to be heterogeneous, as determined by scanning transmission X-ray microscopy (STXM) and powder X-ray diffraction. Results from molecular dynamics simulations supported the heterogeneous nature of the catalysts but also pointed toward large regions within the interlayers that may be filled with nonreactive hydrated Fe oxides resulting from the organic cation treatment. The exchangeable Fe content of the organic treated clays, as determined by AAS and ICP measurements, was observed to be higher than expected relative to that of Fe-saturated clay, substantiating this hypothesis. These findings have implications for the development of substrate-specific clay catalysts, where the composition and configuration of exchangeable cations can be matched to a particular substrate or reaction.

Enhanced CO 2 trapping in water ice via atmospheric deposition with relevance to Mars

It has been suggested that inclusions of CO 2 or CO 2 clathrate hydrates may comprise a portion of the polar deposits on Mars. Here we present results from an experimental study in which CO 2 molecules were trapped in water ice deposited from CO 2/H 2O atmospheres at temperatures relevant for the polar regions of Mars. Fourier-Transform Infrared spectroscopy was used to monitor the phase of the condensed ice, and temperature programmed desorption was used to quantify the ratio of species in the generated ice films. Our results show that when H 2O ice is deposited at 140–165 K, CO 2 is trapped in large quantities, greater than expected based on lower temperature studies in amorphous ice. The trapping occurs at pressures well below the condensation point for pure CO 2 ice, and therefore this mechanism may allow for CO 2 deposition at the poles during warmer periods. The amount of trapped CO 2 varied from 3% to 16% by mass at 160 K, depending on the substrate studied. Substrates studied were a tetrahydrofuran (C 4H 8O) base clathrate and Fe–montmorillonite clay, an analog for Mars soil. Experimental evidence indicates that the ice structures are likely CO 2 clathrate hydrates. These results have implications for the CO 2 content, overall composition, and density of the polar deposits on Mars.

Structure, surface morphology, thermal and flammability characterizations of polyamide6/organic-modified Fe-montmorillonite nanocomposite fibers functionalized by sputter coating of silicon

In the present work, Fe-montmorillonite was synthesized by hydrothermal method, and then was modified by cetyltrimethyl ammonium bromide (CTAB). The polyamide6 (PA6) nanofibers and PA6/organic-modified Fe-montmorillonite (Fe-OMT) nanocomposite fibers were firstly prepared by a facile compounding process with electrospinning, and then coated by silicon nanoparticles (Si) using magnetron sputter technique. The High-resolution transmission electron microscopy (HRTEM) image indicated that the silicate clay layers were well dispersed within the nanocomposite fibers and aligned almost along the axis of the nanofibers. The influences of the Si sputter coating on structures, surface morphology, thermal and flammability properties of PA6 nanocomposite fibers were characterized by Scanning electron microscope (SEM), Energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Atomic force microscope (AFM), Thermogravimetric analyses (TGA) and Micro Combustion Calorimeter (MCC), respectively. The SEM images showed that the diameters of nanocomposite fibers were decreased with the loadings of the Fe-OMT, and the Si thin film with nanoparticles were well coated on the surface of homogeneous and cylindrical nanofibers. The EDX analyses confirmed the presences of the Fe-OMT and Si nanoparticles on the nanofibers. The XPS spectra reflected the chemical features of the deposited nanostructures. The AFM observations revealed a remarkable difference in the surface morphology of nanocomposite fibers after sputter coating. The TGA analyses indicated the barrier effects of silicate clay layers, catalysis effect of Fe 3+ and synergistic effects between the Fe-OMT and Si improved thermal stability properties of the coated nanocomposite fibers. It was found from the MCC tests that the peak of heat release rate (PHRR) of the coated nanocomposite fibers decreased significantly, contributing to the improved flame retardant properties.

Structures, thermal stability, and crystalline properties of polyamide6/organic-modified Fe-montmorillonite composite nanofibers by electrospinning

In the present work, Fe-montmorillonite (Fe-MMT) was synthesized by hydrothermal method, and then was modified by cetyltrimethyl ammonium bromide (CTAB). The polyamide6 (PA6)/organic-modified Fe-montmorillonite (Fe-OMT) composite nanofibers were prepared by facile compounding and electrospinning. Fe-OMT was first dispersed in N, N-dimethyl formamide and then compounded with PA6 which was dissolved in formic acid. The composite solutions were electrospun to form PA6/Fe-OMT composite nanofibers. The structure, morphology, thermal stability, and crystalline properties of the composite nanofibers were characterized by Fourier transfer infrared (FTIR) spectra, Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), High-resolution electron microscopy (HREM), Scanning electron microscopy (SEM), and Thermogravimetric analyses (TGA), respectively. It was found that the silicate clay layers were well exfoliated within the composite nanofibers and were oriented along the fiber axis. The SEM images indicated that the loading of Fe-OMT decreased the diameters of composite nanofibers. TGA analyses revealed that the thermal stability was notably improved in the presence of silicate clay. It was also observed from wide-angle XRD analyses that the presence of nanoclays improved the γ-form crystals and induced the formations of α-form crystals of the PA6, attributed to effective nucleating effects of silicate clay platelets.

Structure, morphology, thermal stability and carbonization mechanism studies of electrospun PA6/Fe-OMT nanocomposite fibers

In the present work, Fe-montmorillonite (Fe-MMT) was synthesized by hydrothermal method, and then was modified by cetyltrimethyl ammonium bromide (CTAB). The polyamide 6 (PA6)/organic-modified Fe-montmorillonite (Fe-OMT) nanocomposite fibers were prepared by a facile compounding and electrospinning. The catalyzing carbonization studies of the Fe-OMT based on PA6 nanocomposite fibers were performed. It was found from High-resolution electron microscopic (HREM) observations that the silicate clay layers were well dispersed within the nanocomposite fibers and was oriented along the fiber axis. The Scanning electron microscopic (SEM) images indicated that the nanofibers were randomly distributed to form the fibrous web and the Fe-OMT additives decreased the diameters of nanocomposite fibers. The Thermogravimetric analyses (TGA) revealed that the loading of the Fe-OMT led to the crosslinking of the PA6, promoted the charred residue yield and catalytic graphitization effect. The structure and morphology of the purified charred residue, characterized by XRD, HREM, Selected area electron diffraction (SAED) and Laser Raman spectroscopic (LR), approved further the presence of graphite sheets. The possible catalyzing carbonization mechanisms included: (1) catalyzing effect of the Fe 3+, which promoted the crosslinking of polymer, (2) Hofmann degradation of the Fe-OMT, whose degraded products had also positive role in promoting crosslinking reactions, (3) gas barrier properties of the nano-dispersed silicate clay layers stopped or reduced the releases of the pyrolytic products, which was dehydrogenated and aromatized to form graphite.

Influence of Fe‐MMT on the fire retarding behavior and mechanical property of (ethylene‐vinyl acetate copolymer/magnesium hydroxide) composite

AbstractIn this work, Fe‐montmorillonite (Fe‐MMT) is synthesized and used as a synergistic agent in ethylene vinyl acetate/magnesium hydroxide (EVA/MH) flame retardant formulations. The synergistic effect of Fe‐MMT with magnesium hydroxide (MH) as the halogen‐free flame retardant for ethylene vinyl acetate (EVA) is studied by thermogravimetric analysis (TGA), limiting the oxygen index (LOI), UL‐94, and cone calorimetry test. Compared with that of Na‐MMT, it indicates that the synergistic effects of Fe‐MMT enhance the LOI value of EVA/MH polymer and improve the thermal stability and reduce the heat release rate (HRR). The structure and morphology of nanocomposites are studied by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The mechanical properties of the EVA composites have also been studied here, indicating that the use of Fe‐MMT reduces the amount of inorganic fillers. MH hence enhances the mechanical properties of the EVA composite while keeping the UL‐94 V‐0 rating. Copyright © 2008 John Wiley & Sons, Ltd.

Influence of Fe‐MMT on crosslinking and thermal degradation in silicone rubber/clay nanocomposites

AbstractIn this article, silicone rubber (SR)/clay nanocomposites were synthesized by a melt‐intercalation process using synthetic Fe‐montmorillonite (Fe‐MMT) and natural Na‐MMT which were modified by cetyltrimethyl ammonium bromide (CTAB). This study has been designed to determine if the presence of structural iron in the matrix can result in radical trapping and then enhance thermal stability, affect the crosslinking degree and elongation. The SR/clay nanocomposites were characterized by X‐ray diffraction (XRD) patterns and transmission electron microscopy (TEM). Exfoliated and intercalated nanocomposites were obtained. Thermo gravimetric analysis (TGA) and mechanical performance were applied to test the properties of the SR/clay nanocomposites. The presence of iron significantly increased the onset temperature of thermal degradation in SR/Fe‐MMT nanocomposites. The thermal stability, gel fraction and mechanical property of SR/Fe‐MMT were different from the SR/Na‐MMT nanocomposites. So the iron not only in thermal degradation but in the vulcanization process acted as an antioxidant and radicals trap. Copyright © 2006 John Wiley & Sons, Ltd.

Synthesis and properties of poly(methyl methacrylate)/clay nanocomposites using natural montmorillonite and synthetic Fe‐montmorillonite by emulsion polymerization

AbstractIn this article, Fe‐montmorillonite (Fe‐MMT) was synthesized by hydrothermal method. For the first time, Fe‐MMT was modified by cetyltrimethyl ammonium bromide (CTAB), and poly(methyl methacrylate)(PMMA)/Fe‐MMT nanocomposites were synthesized by emulsion polymerization. Then poly(methyl methacrylate)(PMMA)/natural montmorillonite (Na‐MMT) and PMMA/Fe‐MMT nanocomposites were compared by Fourier transform infrared (FTIR) spectra, X‐ray diffraction (XRD) patterns, transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA). By XRD and TEM, it was found out that the morphology of PMMA/Fe‐MMT nanocomposites was different from that of the PMMA/Fe‐MMT nanocomposites when the content of two types of clay was same in the PMMA matrix. It was possible that the presence of iron may lead to some radical trapping, which enhances intragallery polymerization to be developed to improve layer dispersion in PMMA/Fe‐MMT systems. In TGA curves, the thermal stability and residue at 600°C of PMMA/Fe‐MMT nanocomposites were higher than those of PMMA/Na‐MMT nanocomposites. Those dissimilarities were probably caused by structural Fe ion in the lattice of Fe‐MMT. POLYM. COMPOS., 27:49–54, 2006. © 2005 Society of Plastics Engineers