Interlayer Space Of Clay Research Articles

Immobilization of cobalt(III) Schiff base complexes onto Montmorillonite-K10: Synthesis, experimental and theoretical structural determination

The [Co(naphophen)(PPh3)(OH2)]ClO4 and [Co(naphophen)(PBu3)(OH2)]BF4 (where naphophen=bis(naphthaldehyde)1,2-phenylenediimine) complexes were synthesized and chracterized by FT-IR, UV–Vis, 1H NMR, 13C NMR spectroscopy and elemental analysis techniques. The coordination geometry of the synthesized complexes were determined by X-ray crystallography. Cobalt (III) complexes have six-coordinated pseudo-octahedral geometry in which the O(1), O(2), N(1) and N(2) atoms of the Schiff base forms the equatorial plane. These complexes showed a dimeric structure via hydrogen bonding between the phenolate oxygen and the hydrogens of the coordinated H2O molecule. The theoretical calculations were also performed to optimize the structure of the complexes in the gas phase to confirm the structures proposed by X-ray crystallography. In addition, UV–Visible and IR spectra of complexes were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification. The synthesized complexes were incorporated onto the Montmorillonite-K10 nanoclay via simple ion-exchange reaction. The structure and morphology of the obtained nanohybrids were identified by FT-IR, XRD, TGA/DTA, SEM and TEM techniques. Based on the XRD results of the new nanohybrid materials, the Schiff base complexes were intercalated in the interlayer spaces of clay. SEM and TEM micrographs of the clay/complex shows that the resulting hybrid nanomaterials has layer structures.

Effect of the dispersive method in the preparation of the polyurethane/hydrotalcite nanocomposites by in situ polymerization

The dispersions were prepared in the proportion of 1g LDH to every 100ml of 1,6-hexamethylenediisocyanate employing four different methodologies. The FTIR results of the dispersions confirmed the presence of monomer in the clay interlayer space, for all methods studied. The XRD analysis showed that the presence of isocyanate contributed to a small structural disorder. Any significant differences between the experimental procedures adopted were observed in TGA results, whereas visual analysis showed that methodology combining ultraturrax and ultrasound bath (TBT) was more effective for dispersion and incorporation of the monomer remaining stable for about a month.The dispersions studied were used in the synthesis of polyurethane nanocomposite. The in situ polymerization step had as objective favor the dispersion of nanofiller during the growth of the polymer chains. The polyurethane obtained was confirmed by the presence of characteristic bands of the urethane group in the FTIR spectrum. The diffraction patterns indicated that in situ polymerization contributed to the structural disorder of the nanocomposites. The strain sweep was carried out by rubber process analyzer (RPA), the lowest values of Payne effect (G0−G∞) were to TBT and T methodologies suggesting a lower filler-filler interaction.The results of the dynamic mechanical thermal analysis (DMTA) showed significant differences that were associated with the dispersion method adopted and also a stoichiometry imbalance due to the interactions of the isocyanate with the hydroxyl groups of the hydrotalcite and/or water molecules within interlayer space and/or air moisture. SEM micrographs revealed better dispersion in the clay polyurethane nanocomposites, whose nanofiller was previously dispersed in the isocyanate monomer.

Nature and formation of interlayer fillings in clay minerals in Albeluvisols from the Carpathian Foothills, Poland

The occurrence of interlayer fillings in clay minerals in the slightly acidic soils of humid temperate zone is a very common and characteristic feature. According to the research literature, the interlayer fillings may be composed of mineral and/or organic materials. The formation of mineral-interlayered clay minerals in soils is related to weathering, which leads to the liberation of cations from the crystalline structure of soil minerals and their subsequent sorption and fixation as a hydroxyl sheet within interlayer spaces of swelling clay minerals, or it may be due to the weathering of chlorite and partial removal of the hydroxyl sheet from interlayer spaces. The formation of organic interlayering within clays is related to interactions between organic and mineral colloids occurring in soil environment. The main aim of the present study was to determine the nature and formation of the interlayer fillings in clay minerals in four Albeluvisols from the Carpathian Foothills in southern Poland showing the occurrence of a fragipan and various degrees of bleaching due to periodic stagnation of water as well as ongoing land use (i.e. forest soils vs. arable soils). This was done using research results obtained from X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR and FTIR-ATR), and chemical analysis. The obtained results show that Albeluvisols from the Carpathian Foothills in Poland are characterized by the occurrence of clay minerals with interlayer fillings, which are the most developed in the upper soil horizons (A, AE, and E). The nature of interlayer fillings in clay minerals in the Albeluvisols studied is mainly organic; however, an additional presence of very small amounts of metal-hydroxy polymers in the interlayer space of clays cannot be completely excluded. Clay minerals with interlayer organic fillings found in the upper soil horizons are formed from swelling clays (smectite and vermiculite) due to the accumulation of organic matter in the interlayers during pedogenesis. The same pattern of clay mineral transformation (i.e. swelling clays into interlayered clays) is observed in Albeluvisols showing strong bleaching and slight bleaching and subject to different forms of land use (i.e. forest soils vs. arable soils). Most likely, this is related to quite similar physical and chemical properties of the soils as well as similar environmental conditions (except of ongoing land use). Quantity of organic matter does not play a crucial role in the formation of organic interlayered clays in soil environment. The most important is low pH (below 5.5) of soil solution and the presence of expandable clay minerals in soil material.

Reactive adsorption of pharmaceuticals on tin oxide pillared montmorillonite: Effect of visible light exposure

• Montmorillonite was pillared with tin oxide. • As increase in the surface area was found owing to the deposition of SnO 2 . • The pillared clay was used for adsorption of trimethoprim and sulfamethoxazole. • As increase in the adsorption was found compared to the initial clay. • Solar light decomposes trimethoprim and thus increases its adsorption in small pores. Montmorillonite (Mt) clay was pillared with SnO 2 and tested as an adsorbent for the removal pharmaceuticals trimethoprim (TMP) and sulfamethoxazole (SMX) frequently present in wastewaters. Adsorption process was carried out in dynamic conditions and the effects of light exposure were investigated. The initial and modified clays were characterized using XRD, FTIR, SEM, potentiometric titration, TA/MS and adsorption of nitrogen. The XRD analysis revealed an enlargement of the clay’s interlayer space as a consequence of SnO 2 particles intercalation into the clay interlayer spaces. A marked increase in the volume of mesopores was also noticed. It indicated the precipitation of tin species on the flake surface. These changes resulted in a five-fold increase in TMP adsorption. Upon exposure to light a 30% increase in TMP adsorption was found in comparison to the performance in the dark. The good performance of the modified clay was linked to specific acid–base and electrostatic interactions of TMP with the Lewis acid sites of SnO 2 . Since exposure to solar light resulted in the decomposition of some TMP adsorbed on the surface, those smaller molecules formed were able to relocate to small pores of higher adsorption energy, which were initially inaccessible for TMP. SMX was not adsorbed on the surface of the modified clay owing mainly to its acidic character.

Biopolymer nanocomposites based on poly(hydroxybutyrate-co -hydroxyvalerate) reinforced by a non-ionic organoclay

In this study, a nanocomposite based on a biodegradable polymer poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) reinforced by triethylene glycol mono-n-decyl ether (C10E3) non-ionic organoclay (C10E3-Mt) was prepared. The morphology and the thermal and mechanical properties of PHBV/C10E3-Mt were compared with those of PHBV nanocomposites prepared using commercial organically modified montmorillonite Cloisite® 30B (OMt) and raw montmorillonite (Mt). Nanocomposites with 3 wt% nanoparticles were obtained by melt processing. The high level of dispersion with improved interfacial interactions between OMt and polymer led to an increase in the thermal stability and modulus of PHBV. However, this nanocomposite presented a lower strain before fracture, typical of brittle behavior. The transmission electron microscopy and wide angle X-ray diffraction results revealed a significant increase in the interlayer spacing of clay for the PHBV/C10E3-Mt nanocomposite, which was favored by the wide expansion of the platelets of the starting non-ionic organoclay. This characteristic of C10E3-Mt, together with its hydrophobic behavior, allowed its easy incorporation in the PHBV matrix, thus improving the processing and maintaining a high modulus with increased material toughness. © 2014 Society of Chemical Industry

Towards Novel Multifunctional Pillared Nanostructures: Effective Intercalation of Adamantylamine in Graphene Oxide and Smectite Clays

Multifunctional pillared materials are synthesized by the intercalation of cage‐shaped adamantylamine (ADMA) molecules into the interlayer space of graphite oxide (GO) and aluminosilicate clays. The physicochemical and structural properties of these hybrids, determined by X‐ray diffraction (XRD), Fourier transform infrared (FTIR), Raman and X‐ray photoemission (XPS) spectroscopies and transmission electron microscopy (TEM) show that they can serve as tunable hydrophobic/hydrophilic and stereospecific nanotemplates. Thus, in ADMA‐pillared clay hybrids, the phyllomorphous clay provides a hydrophilic nanoenvironment where the local hydrophobicity is modulated by the presence of ADMA moieties. On the other hand, in the ADMA‐GO hybrid, both the aromatic rings of GO sheets and the ADMA molecules define a hydrophobic nanoenvironment where sp3‐oxo moieties (epoxy, hydroxyl and carboxyl groups), present on GO, modulate hydrophilicity. As test applications, these pillared nanostructures are capable of selective/stereospecific trapping of small chlorophenols or can act as cytotoxic agents.

Chitosan coated layered clay montmorillonite nanocomposites modulate oral delivery of paclitaxel in colonic cancer

Paclitaxel (PTX), an antineoplastic bioactive, its clinical applications were hampered by its poor biopharmaceutical properties. There is need of safe, therapeutically effective and patient compliant drug delivery system. Clay minerals play a very crucial role in modulating drug delivery. The study deals with the investigation of a chitosan (CS) coated interlayer gallery of Na+ clay montmorillonite (MMT) and cationic paclitaxel (PTX) as a new drug delivery device to overcome PTX toxicity and enhance its therapeutic efficacy. PTX was intercalated into an interlayer gallery of MMT by an ion exchange reaction. Effect of different reaction conditions like time, pH and initial drug concentration on intercalation were studied. Optimised PTX-MMT hybrid nanocomposites were coated with biopolymer CS to get PTX-MMT-CS nanocomposites and characterised. Optimum intercalation (57·75%) of PTX molecules within the interlayer space of MMT was achieved with the pH of 6 at 3 h for 120 mg of PTX. The X-ray diffraction, Fourier transform infra red spectra and thermal analysis indicated the PTX intercalated into the clay interlayer space and stabilized in the longitudinal monolayer by electrostatic interaction. The surface morphology showed smooth layered surface. Nanocomposites demonstrated a controlled release of PTX and 1·2 fold improvement in vitro anticancer activities towards human colon cancer COLO-205 cells. This new nanocomposite material is a potential drug delivery system for oral administration of the anti-tumoral drug PTX, an alternative to the present intravenous administration.

Catalytic degradation of orange G under microwave irradiation with a novel nanohybrid catalyst

Catalytic degradation of pollutants under simultaneous exposure to ultraviolet–visible and microwave irradiations ubiquitously in presence of semiconductor photcatalysts like TiO2 have been found highly efficient. TiO2 being the most prominent photocatalyst in the above process, poses environmental and health hazard due to its nano form. We therefore aim to develop an efficient catalyst for dye degradation by replacing the semiconductor photocatalyst with a polymer semiconductor-based nanohybrid and also ruling out exposure to UV irradiation. Nanohybrid of poly(1-naphthylamine) (PNA) with bentonite (Bent) clay was synthesized under microwave irradiation. Fourier transform infrared spectroscopy revealed emeraldine form of PNA in the nanohybrid while ultraviolet–visible spectra established the conducting state of bentonite/poly(1-naphthylamine) nanohybrid. Formation of vertical chains of PNA in the interlayer space of bentonite clay was established by X-ray diffraction and transmission electron microscopy showed core–shell structure of the bentonite/poly(1-naphthylamine) nanohybrid with size in the range of 140–200nm. Cyclic voltammetry studies showed that the nanohybrid was more electroactive than pure bentonite. Surface charge and surface area of the catalyst was determined to explain its catalytic activity. The nanohybrid catalyzed dye degradation under microwave irradiation at 30°C and showed 2.0–2.7 times higher catalytic efficiency as compared to pure bentonite. Liquid chromatographic–mass spectroscopic results showed that dye was degraded rapidly into intermediates of low m/z values: 285, 143, 119, 113 and 60. The catalyst was usable to six cycles.

Improved photostability of hydrophobic natural dye incorporated in organo-modified hydrotalcite

β-carotene and annatto extract are typical carotenoids used as safe colorants for foods. However, the instability against irradiation limits their wide use. The improvement of stability was investigated by the intercalation of dye into the interlayer space of the anion-exchangeable clay, hydrotalcite. A hydrophobic environment was constructed in the interlayer space of the hydrotalcite by its modification with anionic surfactants (dodecyl sulfate and dodecylbenzene sulfonate). The lipophilic β-carotene and annatto dye were successfully incorporated into the organo-modified hydrotalcite, and the incorporated dyes exhibited improved photostability under visible irradiation from a 100W halogen lamp (190klux) in the air. The effect of the stabilization on the anionic annatto dye was higher by the incorporation in the modified hydrotalcite than that in the modified cation exchangeable clay, suggesting that the polarity of the clay sheet had some influence on the stabilization of the incorporated dye. The stabilization effect of β-carotene was not so significant as that of the annatto dye, because sufficient intercalation of non-polar β-carotene might require stronger hydrophobic environment. The π–π interaction between the β-carotene and the benzene ring of dodecylbenzene sulfonate was found to contribute to the stability enhancement.

Morphology and Mechanical Property of Epoxy-Clay Nanocomposites Prepared by Ultrasonication

Epoxy-clay nanocomposites have been synthesized using organically modified montmorillonite nanoclay, Nanomer I.30E as nanoreinforcement in diglycidyl ether of bisphenol A (DGEBA) epoxy using ultrasonication. X-ray diffraction and TEM analysis showed that the interlayer spacing of clay increased as a result of sonication mixing. It was observed that the morphology of the resultant nanocomposites were dominated by disordered intercalated morphology with some ordered intercalated structure. Tensile tests results illustrated that while the addition of nanoclay increased the modulus of elasticity, noticeable reduction in strength and failure strain was observed. Fractographic analysis was curried out for the tensile fracture surfaces using SEM which illustrated that the roughness of the nanocomposites surface were high compared with the smooth surfaces of the pure epoxy indicating an improvement in the fracture toughness. It also demonstrated that during tensile loading for nanocomposites the cracks were initiated at either clay aggregates or microvoids which explained the reduction in strength for nanocomposites.

Ethylene glycol intercalation in smectites. Molecular dynamics simulation studies

Molecular dynamics simulations were performed in order to study the interactions of ethylene glycol (EG) with smectite. The simulations have also taken into account that EG–smectite complex contains, as a rule, some adsorbed water molecules. The simulations results show that in the two-layer glycolate the content of water is about 1.0 H2O per half of the smectite unit cell. For a typical smectite a clear thermodynamic preference for one- or two-layer structure of the complexes was observed. The calculated radial distribution functions and running coordination numbers indicate that the H2O and EG molecules compete for the coordination sites near the calcium ions in the clay interlayer spaces. The EG and H2O packing in the interlayer space is controlled by the differences in the total smectite layer charge, charge distribution, and the type of the interlayer cation, strongly affecting the basal spacing and the structure of the complex. Varying amounts of EG and water and the ratio EG/H2O are, however, the most important factors influencing the extent of the smectite expansion.A comparison of the two-layer structure obtained from MD simulations with previous models leads to the conclusion that the arrangement of EG molecules in the interlayer spaces, typically used in simulations of clay mineral X-ray diffractograms, can be modified. In contrast to the earlier Reynolds model (1965), the main difference is that the interlayer ions tend to change their positions depending on the specific distribution of the clay mineral charge. In the case of montmorillonite, Ca2+ ions are located in the middle of the interlayer space, while for beidellite they are located much closer to the clay mineral surface. Water molecules in this structure do not form distinct layers but are instead spread out with a tendency to be concentrated closer to the interlayer ions and to the smectite surface. One-layer structure of EG/water–smectite complex, characteristic of vermiculite is also proposed.

Influence of modifying agents of organoclay on properties of nanocomposites based on natural rubber

Sodium-montmorillonite (Na-MMT) nanoclay was modified with four different modifying agents, differing in alkyl chain lengths. The modified organoclay or modified Na-MMT was then compounded with natural rubber (NR) via melt mixing. The influence of alkyl chain length on the properties of organoclay and NR/organoclay nanocomposites was investigated. The longer alkyl chain lengths were more effective in intercalating and expanding the interlayer spacing of clay. Furthermore, the modification of organoclay accelerated the vulcanization reaction of NR, so that the rubber vulcanizates had an increased degree of crosslinking. The mechanical properties of NR were enhanced by the organoclay filling, and larger organoclays interlayer spacing increased the enhancement. This is due to increasing in the crosslinking density of nanocomposites and better dispersion of organoclay in the rubber matrix. A new technique, temperature scanning stress relaxation (TSSR), was used to characterize thermal-mechanical behavior of the composites. The initial stress correlated well with the mechanical properties of nanocomposites. In addition, stress relaxation was observed at the melting temperature of the agent used to modify the organoclay. The organoclays also enhanced the thermal stability, shifting the stress relaxation peaks to higher temperatures.

Atomistic Modeling of the Sorption Free Energy of Dioxins at Clay–Water Interfaces

We employed dispersion corrected DFT and classical methods to identify the factors controlling the adsorption and intercalation of dioxins at water–clay mineral interfaces including sodium and organo-montmorillonites (Na-, TMA-, and HDTMA-Mont) and pyrophyllite. To evaluate the intrinsic sorptive capacity of the clay minerals, the sorption free energies of dioxins at the clay {001} surfaces were calculated, and this showed that the hydrophobicity of the surface is a factor controlling the adsorption. The intercalation of dioxins from the external solvent into the interlayer space of clays was also evaluated, showing the importance of the presence of organic cations. We found that organoclays have sufficient hydrophobicity with large organic cations, and this coupled with the swelling properties of montmorillonite ensures effective adsorption from an aqueous environment. HDTMA-Mont is shown to have these features and that the dioxins were immobilized within the long alkyl chains of the counterions.

Controlling the growth of polycarbazole within the silicate galleries using peroxides via microwave-assisted green synthesis

The scientific challenges involved in the creation of organic–inorganic hybrid materials based on layered silicates with controlled morphological, optical and electronic properties have evolved considerable interest during the last few decades. The interlayer gap in the Bentonite clay provides an interesting, confined environment for the accommodation of the guest molecule at the nanoscale. Moreover, solid state reactions carried out using the reactants confined in clays, zeolites, silica, alumina or other matrices via microwave irradiation not only produce structures of controlled growth but bring down the handling costs due to simplification of experimental procedure which is important in terms of environmentally benign large scale industrial synthesis. This article highlights for the first time the effect of peroxides in controlling the properties of polycarbazole (PCz) within the Bentonite clay interlayer space in terms of morphology, spectral, and fluorescent properties synthesized through microwave-assisted solid-state intercalation. The orientation of the polymer within such restricted nanoscale environment is expected to be a significant solution for obtaining a better control of the molecular architecture.

Preparation of urea formaldehyde resin/layered silicate nanocomposites

PurposeThe purpose of the research was as follows. In situ modified urea formaldehyde resins were prepared from clay (montmorillonite) and organoclay in the presence of base catalyst. Different clay contents (1 wt%, 3 wt%, 6 wt%) were used to produce clay modified nanocomposite resins. These nanocomposites were characterized with FT‐IR, XRD as structural analysis and DSC as thermal analysis and their hardness was evaluated as mechanical analysis. The thermal results was compatible with hardness measurements and showed that using clay/organoclay added resin as a surface coating material provides significant improvement.Design/methodology/approachDuring synthesis of the resin, modification was carried out using urea/formaldehyde with molar ratio of 1/1.6, under basic medium with pH=10 and with temperature of 70°C by loading pristine and organomodified layered silicates.FindingsX‐ray diffraction (XRD) results indicate that the interlayer space of pristine clay was increased significantly by one step, seeing that one step processes are crucial for industrial applications.Research limitations/implicationsThe reaction mixture must be stirred continuously. Temperature should be controlled in order to prevent the thermal curing of urea formaldehyde resin.Practical implicationsThis study provides technical information for the synthesis of nanocomposite resins. The clay or organoclay modified resins may also promote the adhesive strength of coating and also inhibit corrosion effects to metal surfaces of the coated area.Social implicationsThis resin will be used for the coating material.Originality/valueAs Tg‐Tm region of some nanocomposites is enhanced, and by assessing the results of hardness measurements, it is concluded that these samples have further improved mechanical properties as a coating material than urea formaldehyde resin has.

Effects of exchanged ammonium cations on structure characteristics and CO2 adsorption capacities of bentonite clay

Different alkali and alkaline earth cation forms of bentonite clay were exchanged with protonated mono-, di- and triethanolamine compounds, to study the effect of the exchanged ammonium cations on the structure characteristics, thermal behavior, surface properties and CO2 adsorption capacities of bentonite clay. The revolution of the interlayer structure characteristics, thermal properties, the specific surface area and elemental analysis were characterized by XRD, FTIR, TGA, BET and CHNS techniques respectively, while the CO2 adsorption capacities were gravimetrically measured by using magnetic suspension balance (MSB) equipment. It was found that the intercalation of ammonium cations into the interlayer space of bentonite clay induced a step change in its basal spacing, depending on their molar mass and the interlayer molecular arrangement. The presence of the characteristic IR peaks of amine compounds in the spectra of bentonite clay adsorbents modified by amines was qualitatively supported by the incorporation of ammonium cations in the interlayer space of bentonite, while the presence of C, H and N elements using CHNS technique was quantitatively confirmed by the intercalation process of amine compounds. It was also found that the molar mass of amines has an inverse effect on the amount of the adsorbed water (intensity), its desorption temperature (position) and the specific surface area of the synthesized materials. The CO2 adsorption capacities on all the studied bentonite clay adsorbents modified by amines were found to increase between 2.68 and 3.15mmol/g, compared to 0.93mmol/g for untreated bentonite at the studied temperature and pressure. As expected, bentonite clay modified with di- and triethanolammonium cations showed lower CO2 adsorption capacities than that treated with monoethanolammonium cations, due to their low specific surface area.

Les complications neurologiques de l’avitaminose B12 (à propos de neuf cas)

Nanocomposites based on the intercalation of chitosan, a cationic natural polymer, in Na+-montmorillonite are bidimensional nanostructured materials provided of anionic exchange sites (–NH3+X−). This fact is due to the special arrangement of the biopolymer as a bilayer when the amount of intercalated chitosan is higher than the cationic exchange capacity (CEC) of the clay. Therefore, the objective of this work is the application of such biopolymer–clay nanocomposites in the development of electrochemical sensors for the potentiometric determination of anionic species.The high affinity between the chitosan and the montmorillonite clay substrate is the basis of the high stability of the intercalated biopolymer against desorption or degradation, and, in consequence, of the long-term stability of the developed sensors. The film-forming tendency of chitosan is reduced due to its interaction with the montmorillonite, leading to robust three-dimensional nanocomposites that exhibit both structural and functional properties. Such materials are combined with graphite particles and, thus, employed simultaneously as the active phase and the electronic collector of the developed electrochemical sensors. Due to the nature of their components, such devices are provided of low environmental impact. These bulk-modified electrodes exhibit numerous advantages as easy surface renewal, ruggedness and durability and, at the same time, the biopolymer–clay nanocomposites are a reservoir of the active phase. The resulting sensors are applied in the determination of several anions, showing a higher selectivity towards monovalent rather than to di- or trivalent anions and the best potentiometric response towards nitrate ions. This remarkable selectivity may be attributed to the special conformation of the biopolymer in the clay interlayer space.

Maghnite-H+, An Eco-catalyst layered (Algerian Montmorillonite) for Synthesis of Polyaniline/Maghnite Nanocomposites

The nanocomposites namely Polyaniline/Maghnite clay (PANI-Mag) composites were synthesized by solution polymerization of aniline in the presence of sulfuric acid and amount of potassium persulfate (PPS), with molar ratio of monomer to oxidant of 2:1, the aniline was polymerized and largely incorporated into the Maghnite,which was confirmed by FTIR ,HNMR spectra and UV-Vis spectroscopy shows some peaks shifts, which indicate the formation of some new bonds and support the intercalation of PANI chains into the interlayer spacing of Maghnite MMT clay. That, the morphology of the PANI-Mag composites changed according to the proportion of clay. The conductive emeraldine salt form of polyaniline PANI-ES is inserted into the layers of maghnite clay to produce the hybrid with high conductivity and solubility in various organic solvents. The resulting organic-inorganic hybrid material, PANI-Mag has been characterized by various physicochemical techniques.

Influence of “expanded clay” on the microstructure and fatigue crack growth behavior of carbon black filled NR composites

In this study, organo-montmorillonite (OMt) was treated with long alkyl chain containing docosanoic acid in order to obtain expanded organo-montmorillonite (EOMt) with increased interlayer distance. The X-ray diffraction (XRD) patterns confirmed the widening of the interlayer space of clay after intercalation of long alkyl chain docosanoic acid. The role of EOMt nanoparticles on the microstructure and fracture mechanical behavior of carbon black (CB) filled natural rubber (NR) composites was investigated. The microstructure of these clay filled NR/CB composites were revealed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Tear Fatigue Analysis (TFA) tests were carried out using pure-shear test specimen under cyclic conditions to explicate the crack growth behavior of CB filled NR in the presence of EOMt. A significant reduction in crack growth rate was noticed in the presence of only 5 phr of EOMt. The viscoelastic properties obtained from the dynamic mechanical analysis (DMA) for different CB filled NR–clay composites were utilized to estimate the tearing energy qualitatively using the ‘Persson–Brener’ equation. The reinforcement of rubber matrix was investigated by both the static and dynamic mechanical properties. A synergy in reinforcement between clay nanoparticles and CB was attested by the marked enhancement in both mechanical properties.

The Effect of Different Clay Dispersion Methods on the Properties of Polyurethane/Clay Nanocomposites

Polyurethane/clay (PU/clay) nanocomposites were synthesised using polymerisation and dispersion blending methods. The intercalation and exfoliation properties of the PU/clay nanocomposites were investigated by X-ray diffraction and transmission electron microscope. Clay intercalation of polymerised PU/nanocomposites was achieved and the interlayer spacing of clay was greatly enlarged from 17 Å to ~30 Å. Expansion in d-spacing was also observed for PU/clay nanocomposites prepared using dispersion methods. PU/clay nanocomposites prepared from dispersion of clay particles in the prepolymer matrix, followed by chain extension reaction, showed much high molecular weight and significant improvement in mechanical properties as compared with PU/clay nanocomposites produced using polymerisation or a simple high speed blending method in which clay was blended into the PU matrix. For PU/clay nanocomposites prepared using the blending method, high speed dispersion of 2 % clay in PU resulted in approximately a two-fold increase in the Young’s modulus. Further increase in the clay loading from 2 to 6 % made the corresponding nanocomposite polymer films more rigid and stiffer. This study shows that PU/clay nanocomposite properties are highly dependent on the preparation methods and provides useful guidelines for the future design and preparation of PU/clay nanocomposites.