MMT Sheets Research Articles

Synthesis and evaluation of MMT/TiO2 nanotube photocatalysts for enhanced degradation of organic dyes in wastewater

This study aims to synthesize a nanocomposite photocatalyst from naturally sourced clay (montmorillonite, MMT) and titanium dioxide nanotubes (TNTs) to efficiently degrade organic dyes in wastewater under UVC light. The TNTs were synthesized through the hydrothermal method and were randomly attached to both the surface and interlayer spaces of the MMT sheets. Pristine MMT was found to exhibit good adsorption properties, while the TNTs demonstrated strong photocatalytic activity. The combination of these materials in the MMT/TNT nanocomposite resulted in a material that exhibited both adsorption and photocatalytic properties. The dye degradation efficiency of the MMT/TNT nanocomposite reached 95%, which is significantly higher than that of pristine MMT (50%) and TNTs alone (60%). This enhanced performance can be attributed to the synergistic effect between the adsorption capacity of MMT and the photocatalytic activity of TNTs. The study highlights the potential of using naturally sourced materials like MMT in the development of advanced photocatalysts for environmental remediation. The MMT/TNT nanocomposite offers a sustainable and efficient solution for the removal of organic pollutants from wastewater. These findings provide a pathway for further development of high-performance nanocomposites that combine the dual functional properties of adsorption and photocatalysis, contributing to more efficient wastewater treatment technologies.

Layered Clay-Graphene Oxide Nanohybrids for the Reinforcement and Fire-Retardant Properties of Polyurea Matrix.

Nanostructures are more and more evolved through extensive research on their functionalities; thus, the aim of this study was to obtain layered clay–graphene oxide nanohybrids with application as reinforcing agents in polyurea nanocomposites with enhanced thermal–mechanical and fire-retardant properties. Montmorillonite (MMT) was combined with graphene oxide (GO) and amine functionalized graphene oxide (GOD) through a new cation exchange method; the complex nanostructures were analyzed through FTIR and XPS to assess ionic interactions between clay layers and GO sheets by C1s deconvolution and specific C sp3, respective/ly, C-O secondary peaks appearance. The thermal decomposition of nanohybrids showed a great influence of MMT layers in TGA, while the XRD patterns highlighted mutual MMT and GO sheets crystalline-structure disruption by the d (002) shift 2θ = 6.29° to lower values. Furthermore, the nanohybrids were embedded in the polyurea matrix, and the thermo-mechanical analysis gave information about the stiffness of MMT–GO nanocomposites, while GOD insertion within the MMT layers resulted in a 30 °C improvement in the Tg of hard domains, as shown in the DSC study. The micro CT analysis show good dispersion of inorganic structures within the polyurea, while the SEM fracture images revealed smooth surfaces. Cone calorimetry was used to evaluate fire-retardant properties through limiting the oxygen index, and MMT–GOD based nanocomposites showed a 35.4% value.

Effectiveness of photocatalysis of MMT-supported TiO2 and TiO2 nanotubes for rhodamine B degradation

The aim of this paper is to synthesize montmorillonite/TiO2-nanoparticles (MMT/TiO2 and montmorillonite/TiO2-nanotubes (MMT/TiO2-NTs) photocatalysts through a simple wet agitation method based on TiO2 nanoparticles and MMT. They are likely to accumulate the effect of adsorption and photodegradation. Then, the photocatalysts are applied to degrade the rhodamine B in dye effluents. The structural characterizations of photocatalysts are investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDX). The photocatalytic activities and effectiveness of photocatalysts are evaluated through rhodamine B degradation at different concentrations under dark and UV-C irradiation conditions. The results show that the synthesized TiO2-NTs have an average tube diameter of 5 nm and a tube length at least about 110 nm, which are intercalated into MMT sheets in MMT/TiO2-NTs photocatalyst. Meanwhile, TiO2 nanoparticles are immobilized on the surface of MMT sheets in the MMT/TiO2 photocatalyst. The photocatalytic effectiveness of rhodamine B degradation of TiO2-NTs shows a significantly enhance compared to that of TiO2 nanoparticles. However, photocatalytic performance of MMT/TiO2-NTs is lower than that of MMT/TiO2. The degradation effectiveness of MMT/TiO2 photocatalyst reaches to 100% for 3 ppm and 90% at 10 ppm of rhodamine B, while these values are 97.5% and 85.5%, respectively, recorded for MMT/TiO2-NTs.

2D-montmorillonite-dispersed g-C3N4/TiO2 2D/0Dnanocomposite for enhanced photo-induced H2 evolution from glycerol-water mixture

Montmorillonite (MMT) dispersed g-C3N4/TiO2 hybrid nanocomposite for enhanced photo-catalytic hydrogen production from glycerol-water mixture has been investigated. The newly designed composite photo-catalysts were fabricated through a sol-gel assisted hydrothermal method and were characterized by XRD, XPS, SEM, EDX, TEM, FTIR, UV–Vis, Raman and PL spectroscopy. Well-designed g-C3N4/MMT/TiO2 heterojunction composite was obtained with 2D MMT structure, which promoted both visible light absorption and hindered charges recombination rate. The modification of 2D/0D g-C3N4/TiO2 heterojunction with 2D MMT sheets enhances H2 production due to MMT works as a mediator for effective charges trapping and transportation within the composite structure. The g-C3N4/MMT/TiO2 photo-catalyst exhibits highest H2 production of 4425 ppm h−1 g−1 at pH 7.0, which was 2.12 times higher than the pure TiO2 (2085 ppm h−1 g−1). In addition, increasing catalyst loading promotes more H2 evolution and among the different sacrificial reagents, glycerol-water mixture gave highest H2 production due to the presence of α-hydrogen atoms attached to carbon atoms. The enhanced photo-catalytic efficiency can be attributed to synergistic effect of MMT with g-C3N4/TiO2 heterojunction composite, appropriate band structure and transportation of electrons–holes with their hindered recombination rate. These composite catalysts exhibited excellent photo-catalytic stability for H2 production in cyclic runs. Possible reaction mechanism for hydrogen production over g-C3N4/MMT/TiO2 composite has been explained based on the experimental results. The finding of this work would be fruitful for hydrogen production applications with all sustainable systems.

The assembly of a composite based on nano-sheet graphene oxide and montmorillonite

Graphene oxide (GO) nano-sheets were synthesized using a modified Hummers’ method from graphite powder. The Raman spectrum of GO displayed a D-band at 1359 cm−1 and a G-band at 1594 cm−1. The ID/IG value of GO was calculated to be 0.97, suggesting the formation of new sp2 clusters upon reduction. A method was designed to investigate the assembly of the GO/montmorillonite (MMT) composite. After the addition of GO, the typical peaks of montmorillonite in FT-IR spectra shifted, indicating the assembly between GO and MMT. The D-band and G-band reduced sharply in the GO/MMT composite. More importantly, the D-band (1344 cm−1) and G-band (1574 cm−1) shifted significantly and the ID/IG value of the GO/MMT composite was calculated to be 1.13, showing a change in the GO structure. In the addition of 0.04 wt% GO to MMT, the value of interlayer space (d) was up to 13.0 Å measured by XRD due to the insertion of GO into MMT. The evident increases in contents of carbon atoms (26.59%) and nitrogen atoms (3.44%) indicate that GO was successfully combined with MMT. The nano-pores and clay sheets were not observed in the SEM image of GO/clay, but obvious wrinkles, while flexible sheets were observed in the typical scanning electron microscopy images of GO. This further proves that GO was combining with clay. The TEM image shows that the GO nano-sheets were tiled on the surface of MMT sheets. This observation suggests that a stable assembly structure was formed between GO sheets and MMT sheets. The change in particle size of MMT with the addition of GO shows that interaction occurred between GO sheets and MMT sheets, which was further confirmed by the results of zeta potential. Adsorption and insertion were the main mechanisms to assemble GO and MMT.

A facile method of preparing sandwich layered TiO2 in between montmorillonite sheets and its enhanced UV-light photocatalytic activity

The ultrafine dispersing and subsequent self-assembling process of montmorillonite (MMt) micro layers were controlled by pH switch to build sandwich-layer structure of TiO2 intercalated MMt. Different pH controlling processes were carried out during hydrothermal synthesis, and the as-prepared samples were characterized by XRD, SEM, TEM, XPS, FTIR, UV–vis spectra, nitrogen adsorption/desorption analysis, and photocatalytic activities. The FTIR and XRD results reveal that TiO2 is chemically combined with MMt layers by hydrothermal process, which hinders the grain growth and anatase-to-rutile phase transition of loaded TiO2 and the transition temperature is approximately 900 °C. The micro-morphology analysis shows that TiO2 nanoparticles could be successfully intercalated into MMt layers by special pH controlling process, resulting in the expansion of interplanar spacing of MMt and increased interface action between TiO2 nanocrystals and MMt sheets. The size of TiO2 intercalated in the MMt is approximately 15 nm, which is much smaller than blank TiO2. Furthermore, comparing with ordinary surface loaded TiO2, the TiO2 nanoparticles sandwiched in MMt layers display much higher UV-light photocatalytic degradation activity and reliable recycling stability to methyl orange (MO), due to more Ti3+ active sites and larger porous volume caused by intercalation. Differed from previous TiO2-MMt, which has directional arrangement and narrowed interlayer spacing of (001) faces of MMt, such novel pH controlling process gives full play to the advantage of clay sheets to build layered limited TiO2, and solves traditional drawbacks of MMt supporting materials such as light barrier and limited mass transfer efficiency in composed photocatalysts.

Tri-ammonium end functional polyethylene: facile synthesis and application as an intercalation agent

Organo-modification of montmorillonite (MMT) is crucial for the promotion of fine dispersion of MMT into (often hydrophobic) polymer matrix. Ammonium terminated polymers are more efficient in modifying clay compared to small organic cations such as alkyl ammoniums or side functionalized polymers. Herein, tri-amino end functional polyethylene (PE-3N) with low molecular weight was first synthesized via efficient and robust epoxide ring-opening reaction by treating epoxide terminated PE with diethylenetriamine. The chemical structure of PE-3N was unambitiously characterized by chromatographic and spectral methods. By reacting with excessive HCl, PE-3N was subsequently converted to tri-ammonium end functional polyethylene (PE-3N+), which serves as an intercalation agent of MMT. By adjusting the weight ratio of PE-3N+ to pristine MMT (RP/M) applied in static melt intercalation process, correlations between the extent of exfoliation and RP/M were successfully established. XRD results revealed that complete exfoliation of MMT could be afforded when RP/M as low as 1, which is the lowest value ever reported where ammonium-terminated polymers applied as intercalation agents. SEM micrographs observed that MMT sheets were swollen by PE-3N+, affirming the successful modification of MMT. The obtained PE modified MMT may find application in preparing high-performance PE/MMT nanocomposite.

Preparation and characterization of anion-exchange membranes derived from poly(vinylbenzyl chloride-co-styrene) and intercalated montmorillonite

In this paper, three organic intercalating agents containing cations [hexadecyl trimethyl ammonium bromide (CTAB), poly(acrylamide-co-diallyldimethylammonium chloride), and quaternized polyethyleneimine] are used to prepare intercalated montmorillonites (MMT) by ion-exchange method. Then the modified MMTs are doped with vinylbenzyl chloride and styrene copolymer [poly(vinylbenzyl chloride-co-styrene)] for fabricating composite anion-exchange membranes (AEM). Fourier transform infrared, X-raydiffraction, thermogravimetric analysis, scanning electron microscopy, and Mastersizer laser particle size analyzer are employed to characterize the structure and morphology of MMTs and AEMs. The successful intercalation of MMTs is approved, and the MMT intercalated by CTAB shows an interlayer distance of 2.31 nm. The properties of the composite membranes including water uptake, mechanical property, and ionic conductivity are investigated. Among all the AEMs, the composite membrane containing MMT sheets with CTAB demonstrates better compositive performances. It presents an ionic conductivity of 2.09 × 10−2 S cm−1 at 80°C and good alkaline solution stability. Copyright © 2016 John Wiley & Sons, Ltd.

Poly(vinyl alcohol)/GO-MMT nanocomposites: Preparation, structure and properties

A facile, efficient and environment friendly method is established to prepare poly(vinyl alcohol) (PVA) based graphene oxide-montmorillonite (GO-MMT) nanocomposites in aqueous media. GO-MMT nanohybrid is obtained by the combination of GO and MMT in water without any reducing or stabilizing agents. The formation of GO-MMT nanohybrid is due to the hydrogen bonding and crosslinking effects. The sodium ions within MMT sheets act as crosslinkers between GO sheets and MMT platelets. The resultant nanocomposites are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and mechanical testing. Compared to that of pure PVA, PVA nanocomposites show enhanced thermal stabilities and mechanical properties, which results from strong interfacial adhesion of the nanoadditives in PVA matrix. The further increase in the tensile strength and modulus results from strong interaction between PVA chains and layered GO-MMT as well as good mechanical properties of GO-MMT hybrid, compared to PVA/GO and PVA/MMT nanocompsoites.

Synthesis and Characterization of Low-Generation Polyamidoamine (PAMAM) Dendrimer–Sodium Montmorillonite (Na-MMT) Clay Nanocomposites

Polymer-inorganic nanocomposites are a recently developed class of materials that have altered physical or chemical properties with respect to the pure polymer, inorganic host, or their micro- and macrocomposites. Lower generation (G0.0-2.0) polyamidoamine (PAMAM) dendrimer/sodium montmorillonite (Na-MMT) nanocomposites were synthesized in a solution-phase exfoliation adsorption reaction. These are the first reports of the G0.0/ and G1.0/Na-MMT nanocomposites and of a structurally-ordered G2.0/Na-MMT. The materials were characterized using powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). PAMAM characteristics at acidic and basic aqueous media were studied using capillary zone electrophoresis (CZE). Pseudospherical PAMAM dendrimers in aqueous medium attain a highly flattened conformation within the confined space between MMT sheets upon nanocomposite formation. The nanocomposite structure depends on the PAMAM generation and the starting dendrimer/organic composition. G0.0 always forms monolayer structures (d = 0.42 nm), while G2.0 forms monolayer structure, mixed phase, and bilayer structures (d = 0.84 nm) at lower, intermediate, and higher organic content, respectively, showing an interesting monolayer to bilayer transition. G1.0 showed an intermediate behavior, with monolayer to mixed-phase transition at the reactant ratios studied. This monolayer arrangement of PAMAM/clay nanocomposites is reported for the first time. Maximum organic contents of G0.0 monolayer and G2.0 bilayer nanocomposites were ∼7% and ∼14%, respectively. Gallery expansions were similar to those observed with linear polymer intercalates, but the packing fractions (0.31-0.32) were 2-3 times lower. At acidic pH, the nanocomposites forming only monolayer structures are obtained, indicating a stronger electrostatic attraction between MMT and protonated PAMAM, and these nanocomposites formed more slowly and were more ordered. Na(+) ions play a significant role in nanocomposite formation. At high pH, PAMAMs show high mobility, ζ potential, and surface charge densities due to Na(+) complexation in solution. FTIR data indicates that both Na-MMT and PAMAM structural units are preserved in the nanocomposites obtained.

Hybrid materials: Magnetite–Polyethylenimine–Montmorillonite, as magnetic adsorbents for Cr(VI) water treatment

Hybrid materials formed by the combination of a sodium rich Montmorillonite (MMT), with magnetite nanoparticles (40nm, Fe3O4 NPs) coated with Polyethylenimine polymer (PEI 800g/mol or PEI 25000g/mol) were prepared. The intercalation of the magnetite nanoparticles coated with PEI among MMT platelets was achieved by cationic exchange. The resulting materials presented a high degree of exfoliation of the MMT sheets and a good dispersion of Fe3O4 NPs on both the surface and among the layers of MMT. The presence of amine groups in the PEI structure not only aids the exfoliation of the MMT layers, but also gives to the hybrid material the necessary functionality to interact with heavy metals. These hybrid materials were used as magnetic sorbent for the removal of hexavalent chromium from water. The effect that pH, Cr(VI) concentration, and adsorbent material composition have on the Cr(VI) removal efficiency was studied. A complete characterization of the materials was performed. The hybrid materials showed a slight dependence of the removal efficiency with the pH in a wide range (1–9). A maximum amount of adsorption capacity of 8.8mg/g was determined by the Langmuir isotherm. Results show that these hybrid materials can be considered as potential magnetic adsorbent for the Cr(VI) removal from water in a wide range of pH.

The role of polymerizable organophilic clay during preparing polyethylene nanocomposite via filling polymerization

AbstractEffect of polymerizable montmorillonites (P‐MMTs) on the morphology of polyethylene/montmorillonites (PE/MMTs) nanocomposites during filling polymerization was studied. The microstructure analysis showed that the P‐MMTs were more exfoliatable than nonpolymerizable MMTs in the preparation of PE/MMTs nanocomposites. By examining the influence of the polymerization condition on the microstructure of the resultant nanocomposites, it was confirmed that the shear force formed by the mechanical stirring was the driving force of the exfoliation dispersion of MMT sheets during the filling polymerization. Comparatively, the shear force on MMT sheets might be increased due to strong interaction between PE chains linked to the surface of P‐MMTs and the solvents molecules, which is the reason that polymerizable clay is more exfoliatable than nonpolymerizable clay. The copolymerization between polymerizable modifier and ethylene was confirmed by NMR measurements. Furthermore, the morphology of the resultant nanocomposites was influenced by the concentration of the dispersed P‐MMTs. The degree of exfoliation of the resultant nanocomposites at a relatively low concentration was higher than that at a high concentration. This is because of the multiscale organization of the organoclay dispersed in the organic medium. High exfoliation degree of MMTs and improved interaction between PE matrix and P‐MMTs in PE/P‐MMTs nanocomposites led to significant improvements in mechanical properties and barrier properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Mechanism on flame retardancy of polystyrene/clay composites-The effect of surfactants and aggregate state of organoclay

Effects of organically modified montmorillonites (OMMTs) with different type and amount of modifiers on flame retardancy of polystyrene (PS) have been studied. The results from morphology analysis, gas chromatography–mass spectrometry and cone calorimeter have showed different mechanisms for the flame retardancy of PS/OMMTs composites, depending on surface property of OMMTs. One is the catalysis of acid sites formed on the surface of octadecylammonium modified MMT (c-MMT) via Hoffman decomposition on the carbonization of degradation products, which promotes the formation of clay-enriched char barrier. The other is related to chemical effect of inherent properties of MMT sheets on reactive intermediates during combustion, which work in PS/Na-MMT and PS/sodium dodecylsulfonate modified MMT (a-MMT) composites. Furthermore, the effect of the aggregate states of a-MMT on the flame retardancy of PS/a-MMT composites was studied. In the case of a-MMTs from spraying drying, a good protective layer with foam-like aggregate state of MMT sheet was formed in the residue, which results in low peak value of heat release rate of PS/a-MMT composites.

Microstructure and Deformation Behavior of Polyethylene/Montmorillonite Nanocomposites with Strong Interfacial Interaction

Deformation behavior of polyethylene/modified montmorillonites with polymerizable surfactant (PE/P-MMT) nanocomposite with strong interfacial interaction was studied by means of morphology observation and X-ray scattering measurements. The orientation of PE chains was accompanied by the orientation of well-dispersed MMT platelets due to the presence of strong interfacial interaction, and both of the orientations were parallel to the deformation direction. The high degree of orientation of MMT platelets and PE chains resulted from the synergistic movement of PE matrix and MMTs, which originated from the presence of a network-like structure. Meanwhile, the existence of MMT platelets with good mobility during deformation and strong interfacial interaction with PE matrix could further improve the break energy of material by restraining the initiation and growth of cavities during deformation. In contrast, PE/MMT nanocomposite with no strong interfacial interaction and poor dispersed state of MMT sheets showed the weaker orientation of both PE chains and MMT platelets, and a strong cavitation during deformation.

Synthesis and characterization of a novel covalently functionalized organoclay and its polypropylene nanocomposite

AbstractA covalently functionalized organoclay was synthesized successfully through a condensation reaction of SiOH groups on the edge of montmorillonite (MMT) with acryloyl chloride followed by modification with hexadecyltrimethylammonium bromide (CTAB) via an ion‐exchange reaction. Fourier transform infrared confirmed that CC groups had been grafted to MMT sheets. Wide‐angle X‐ray diffraction measurements showed that CTAB had intercalated into MMT interlayers. The content of bonded acryloyl chloride was 2.42 wt % in the functionalized organoclay according to thermogravimetric analysis. Polypropylene (PP) nanocomposites were prepared by melt mixing. Rheological measurements and morphology observations confirmed that PP nanocomposites containing the organoclay bearing CC groups exhibited improved interfacial interaction between PP chains and MMT sheets. Thus, the PP nanocomposites showed not only higher storage modulus and complex viscosity values at low frequencies but also enhanced mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

A Simple Method for Preparing Carbon Nanotubes/Clay Hybrids in Water

A simple novel method for preparing multiwalled carbon nanotubes/montmorillonite (MWNTs/MMT) hybrids has been established through mixing pristine MWNTs in MMT aqueous dispersion. The principle of this method is based on the formation of stable dispersion containing both MWNTs and MMT in water, which results from strong interaction between MWNTs and MMT platelets. Sedimentation experiments, measurements of ζ potential, and Raman spectra have been used to confirm the presence of strong interaction between MWNTs and MMT sheets. The morphology observation for the dried MWNTs/MMT hybrids shows that the obtained hybrids are homogeneous, in which MWNTs exist as the state of single nanotubes that are absorbed on the surface and edge of MMT sheets. In addition, poly(ethylene oxide) (PEO) nanocomposites containing both MWNTs and MMTs are prepared by using this method. An obvious synergistic effect of MMT sheets and MWNTs in improving mechanical properties of PEO matrix has been observed.

STRUCTURAL EVOLUTION AND COMPOSITION CHANGE IN THE SURFACE REGION OF POLYPROPYLENE/CLAY NANOCOMPOSITES ANNEALED AT HIGH TEMPERATURES

A model experiment was done to clear the formation mechanism of protective layers during combustion of polypropylene (PP)/organically modified montmorillonite (OMMT) nanocomposites. The investigation was focused on the effects of annealing temperature on the structural changes and protective layer formation. The decomposition of OMMT and degradation of PP/OMMT nanocomposites were characterized by means of thermogravimetric analysis (TGA). The structural evolution and composition change in the surface region of PP/OMMT nanocomposites during heating were monitored by means of X-ray photoelectron spectroscopy (XPS), ATR-FTIR and field emission scanning electron microscopy (FESEM). The results showed that the formation of the carbonaceous silicate barrier in the surface region of PP/OMMT nanocomposites resulted from the following three processes: (1) The formation of strong acid sites on the MMT sheets, which could promote the degradation of PP and the carbonization of its degradation products; (2) The gases and gas bubbles formed by decomposition of the surfactant and degradation of PP, which pushed the molten sample to the surface; (3) The degradation of PP and the carbonization of the degradation products, which led to accumulation of MMT sheets tightly linked by the char in the surface region.

Polyacrylate/(carboxymethylcellulose modified montmorillonite) superabsorbent nanocomposite: Preparation and water absorbency

AbstractMontmorillonite (MMT) was modified with carboxymethylcellulose (CMC). The X‐ray diffraction (XRD) and FTIR analyses showed that the CMC chains had intercalated into the MMT sheets, and the strong chemical interaction between the ether bonds from CMC and SiO bonds from MMT was the driving force for intercalation. Polyacrylate (PAA)/modified MMT superabsorbent nanocomposites were fabricated by effectively dispersing the modified MMT in acrylic acid solution and polymerizing the acid. The superabsorbent composites were characterized by XRD, TEM, and FTIR. The influence of modified MMT, weight ratio of CMC to MMT, and modified MMT content in the nanocomposites on the water absorbency was investigated. Results showed that the introduction of pure MMT could decrease the water absorbency of the gel, but adding modified MMT could not only effectively increase the water absorbency of the gel, but also improve its water retention ability. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Interaction of functional groups of gelatin and montmorillonite in nanocomposite

AbstractAs an amphoteric polyelectrolyte, gelatin could intercalate into the galleries of montmorillonite (MMT). In this paper, sodium laurate/MMT composites and sodium laurate/dehydroxylated MMT composites were introduced as low molecular simulation to investigate the interaction functional groups of gelatin and MMT. The composites were characterized by X‐ray diffraction (XRD), Fourier transform infrared spectra (FTIR), thermogravimetric analysis (TGA) and 13C nuclear magnetic resonance (13C NMR). Furthermore, the effect of interaction between gelatin and MMT on the mechanical properties of the composites was investigated. The results indicated that COO−, not COOH, in gelatin chains could interact strongly with the MMT sheets. The reactive sites on MMT were hydroxyl groups, which could interact with COO− in gelatin chains by forming hydrogen bonds. The gelatin/MMT composites prepared in alkalic media have better mechanical properties due to stronger interaction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1556–1561, 2006

Synthesis of Exfoliated Monomer Casting Polyamide 6/Na+‐Montmorillonite Nanocomposites by Anionic Ring Opening Polymerization

AbstractSummary: In this work, a novel method using water as a pre‐dispersant of pristine sodium montmorillonite (Na+‐MMT) and ε‐caprolactam (CL) monomer was developed for the preparation of exfoliated monomer casting polyamide 6 (MCPA6)/MMT nanocomposites via in situ anionic ring opening polymerization. The dispersion effect of MMT in the MCPA6 matrix was investigated by means of X‐ray diffraction (XRD), as well as transmission electronic microscopy (TEM). The results indicated that nanoscale dispersed MMT was successfully achieved in the MCPA6 matrix. Furthermore, the addition of a small amount of MMT dramatically improved the thermal stability of MCAP6. Analysis using differential scanning calorimetry (DSC) and XRD indicated that nanoscale dispersed MMT sheets acted as heterogeneous nucleation agents, which favored the formation of the γ‐crystalline form of the MCPA6 matrix.MMT dispersing sketch in the course of polymerization.magnified imageMMT dispersing sketch in the course of polymerization.