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Modified Clay (modified + clay)

Distribution by Scientific Domains

Polymers and Materials Science	88%

Selected Abstracts

Optimization by response surface methodology (RSM) for toluene adsorption onto prepared acid activated clay

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2008
Abdelfattah Amari
Abstract Adsorption of toluene onto acid activated clay was carried out. Modified clay was prepared by acid attack (H2SO4) on raw material. Response surface methodology based on a 2-level, 4-variables central composite orthogonal design was used to evaluate the effects of important parameters on the adsorption of toluene on to activated clay. Temperature (53.8,96.2°C), contact time (0.57,6.93 h), mass ratio of liquid/solid (3.38,7.62) and strength of acid (7.75,57.24%) were chosen as process variables for the optimization. Of these parameters, temperature reaction and time had greater impact on toluene adsorption than did the other parameters. Analysis of variance (ANOVA) shows a good agreement between theoretical analysis and experimental data. The validity of model is verified by an experiment at the optimum conditions. The optimum conditions for the maximum adsorption of toluene onto activated clay are: temperature of 96.2°C, a contact time of 6.93 h, a liquid/solid ratio of 5.98 and strength of acid of 32.94%. Since the predicted values and the actual experimental value obtained for the maximum adsorption of toluene are within 95% confidence intervals, the final model is considered valid and has satisfactory predictive ability. L'adsorption du toluène sur l'argile activée par l'acide est réalisée. L'argile modifiée a été préparée par attaque acide (H2SO4) de la matière première. On a eu recours à la méthodologie de surface de réponse basée sur un plan d'expériences orthogonal composite centré à 2 niveaux et 4 variables afin d'évaluer les effets des paramètres importants pour l'adsorption du toluène sur l'argile activée. La température (53,8°C,96,2°C), le temps de contact (0,57,6,93 h), le rapport massique liquide/solide (3,38,7,62) et la force de l'acide (7,75,57,24%) ont été choisis comme variables de procédé pour l'optimisation. Parmi ces paramètres, le temps de contact et la température ont le plus grand impact sur l'adsorption du toluène. L'analyse de la variance (ANOVA) montre un bon accord avec l'analyse théorique et les données expérimentales. La validité du modèle est vérifiée par une expérience dans les conditions optimales. Les conditions optimales pour l'adsorption du toluène sur l'argile activée sont: la température de 96,2°C, le temps de contact de 6,93 h, le rapport liquide/solide de 5,98 et la force de l'acide de 32,94%. Étant donné que la valeur prédictée et la valeur expérimentale réelle obtenue par l'adsorption maximale du toluène se trouvent dans un intervalle de confiance de 95%, le modèle final est considéré comme valide et possède une capacité de prédiction satisfaisante. [source]

Rigid PVC/(layered silicate) nanocomposites produced through a novel melt-blending approach,

JOURNAL OF VINYL & ADDITIVE TECHNOLOGY, Issue 2 2009
Laurent M. Matuana
On the basis of the fusion behavior of poly(vinyl chloride) (PVC), the influence of compounding route on the properties of PVC/(layered silicate) nanocomposites was studied. Four different compounding addition sequences were examined during the melt compounding of PVC with montmorillonite (MMT) clay, including (a) a direct dry mixing of PVC and nanoclay, (b) an addition of nanoclay at compaction, (c) an addition of nanoclay at the onset of fusion, and (d) an addition of nanoclay at equilibrium torque. Both unmodified sodium montmorillonite (Na+ -MMT) and organically modified montmorillonite (Org.-MMT) clays were used, and the effect of the addition sequence of the clay during compounding on its dispersion in the matrix was evaluated by X-ray diffraction and transmission electron miscroscopy. The surface color change, dynamic mechanical analysis, and flexural and tensile properties of PVC/clay nanocomposites were also studied. The experimental results indicated that both the extent of property improvement and the dispersion of nanoparticles in PVC/(layered silicate) nanocomposites are strongly influenced by the degree of gelation achieved in PVC compounds during processing. The addition of nanoclay to PVC must be accomplished at the onset of fusion, when PVC particles are reduced in size, in order to produce nanocomposites with better nanodispersion and enhanced mechanical properties. Overall, rigid PVC nanocomposites with unmodified clay (Na+ -MMT) were more thermally stable and exhibited better mechanical properties than their counterparts with organically modified clay (Org.-MMT). J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers [source]

Influence of Layered Silicate on the Self-Crosslinking of Polychloroprene and Carboxylated Nitrile Rubber

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 2 2009
Amit Das
Abstract The effect of organically modified clay on the properties of self-crosslinkable carboxylated acrylonitrile-butadiene rubber (XNBR) and polychloroprene rubber (CR) blend is studied. Results of blends produced without crosslinking agents are compared with conventional sulphur cured compounds. Sulphur cured blends exhibit improved physical properties after the incorporation of organophilic-modified clay. In contrast, the self-crosslinked blends do not show any reinforcement after the incorporation of the organoclay. XRD spectra show an intercalation of polymer chain into the gallery gap of the clay in both cases. ATR-IR, DMA and SEM studies of these composites confirm that organoclay particles constrain the self-crosslinking mechanism. The influence of the organoclay on the crystallisation of CR is also shown. [source]

Preparation of Clay/PMMA Nanocomposites with Intercalated or Exfoliated Structure for Bone Cement Synthesis

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 6 2006
Jyh-Horng Wang
Abstract Summary: Clay/PMMA nanocomposites were prepared by melt blending of an organically modified MMT with PMMA under various process conditions. The MMT clay was initially cation exchanged with octadecylammonium to enhance its hydrophobicity and to expand the interlamellar space of the silicate plates. PMMA was then inserted into the inter-lamellar space of the modified clay by melt blending at an elevated temperature. The effects of blending temperature, blending time, and clay/PMMA compositions on the level of expansion and homogenization were investigated. Composites with intercalated and/or exfoliated clay structure were obtained depending upon the process conditions, as confirmed by XRD diffractometry. The thermal decomposition temperature (Td) and glass transition temperature (Tg) of the composites were determined, respectively, by TGA and DSC analyses. Marked improvements, up to 35,°C, of the thermal stability (Td) with respect to pure PMMA were achieved for many of the composite samples. The Tg of the composites, however, does not increase accordingly. Furthermore, a novel type of bone cement was synthesized by applying the clay/PMMA nanocomposites as a substitute for PMMA in a typical formulation. These bone cements demonstrated much higher impact strength and better cell compatibility than the surgical Simplex P cement. Therefore, the bone cements with clay/PMMA nanocomposites meet the requirement for the architectural design of orthopedic surgery. TEM images of an OA-clay/PMMA composite. [source]

Preparation of photodegradable polypropylene/clay composites based on nanoscaled TiO2 immobilized organoclay

POLYMER COMPOSITES, Issue 5 2009
Xiangfu Meng
Photodegradable polypropylene (PP) composites were prepared via melting blending using PP and titanium dioxide (TiO2) immobilized organically modified montmorillonite (organoclay). TiO2 immobilized organoclay (TiO2 -OMT) was synthesized by immobilizing anatase TiO2 nanoparticles on organically modified clay via sol,gel method. The structure and morphology of TiO2 -OMT were characterized by XRD and scanning electron microscope (SEM), which showed that anatase TiO2 nanoparticles with the size range of 8,12 nm were uniformly immobilized on the surface of organoclay layers. Diffuse reflection UV,vis spectra revealed TiO2 -OMT had similar absorbance characters to that of commercial photocatalyst, Degussa P25. The solid-phase photocatalytic degradation of PP/TiO2 -OMT composites was investigated by FTIR, DSC, GPC and SEM. The results indicated that TiO2 -OMT enhanced the photodegradation rate of PP under UV irradiation. This was due to that immobilization of TiO2 nanoparticles on organoclay effectively avoided the formation of aggregation, and thereby increased the interface between PP and TiO2 nanoparticles. After 300 h irradiation, the average molecular weight was reduced by two orders of magnitude. This work presented a promising method for preparation of environment-friendly polymer nanocomposites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers. [source]

Effect of bifunctional modifiers of the clay on the morphology of novolac cured epoxy resin/clay nanocomposites

POLYMER COMPOSITES, Issue 10 2008
Tsung-Yen Tsai
Montmorillonite type clay, (PK-802) is modified by the bifunctional modifiers (2-phenylimidazole/benzalkonium chloride, PI/BEN or 2-methylimidazole/benzalkonium chloride, MI/BEN) with different ratio, which contain a curing agent, BEN, and the promoters/accelerator (PI and MI). These two modifying agents are simultaneously intercalated into the gallery space of pure PK-802. The novolac cured epoxy nanocomposites are prepared with this modified clay by crosslinking polymerization reaction. Wide-angle X-ray diffraction is used to measure the resulting d -spacing of modified PK-802 and the nanocomposites. Thermo-gravimetric analysis is used to characterize the thermal properties of the nanocomposites. The morphology of the nanocomposites is investigated using transmission electron microscopy techniques. Well dispersion of clay into the novolac cured epoxy-clay nanocomposites resulted when simultaneously both the modifying agents with 5:5 mole ratios are used to modify the clay instead of using single modified agent. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source]

Use of a new natural clay to produce poly(methyl methacrylate)-based nanocomposites

POLYMER INTERNATIONAL, Issue 1 2010
Djahida Lerari
Abstract Nanocomposites of poly(methyl methacrylate) (PMMA) filled with 3 wt% of modified natural Algerian clay (AC; montmorillonite type) were prepared by either in situ polymerization of methyl methacrylate initiated by 2,2,-azobisisobutyronitrile or a melt-mixing process with preformed PMMA via twin-screw extrusion. The organo-modification of the AC montmorillonite was achieved by ion exchange of Na+ with octadecyldimethylhydroxyethylammonium bromide. Up to now, this AC montmorillonite has found applications only in the petroleum industry as a rheological additive for drilling muds and in water purification processes; its use as reinforcement in polymer matrices has not been reported yet. The modified clay was characterized using X-ray diffraction (XRD), which showed an important shift of the interlayer spacing after organo-modification. The degree of dispersion of the clay in the polymer matrix and the resulting morphology of nanocomposites were evaluated using XRD and transmission electron microscopy. The resulting intercalated PMMA nanocomposites were analysed using thermogravimetric analysis and differential scanning calorimetry. The glass transition temperature of the nanocomposites was not significantly influenced by the presence of the modified clay while the thermal stability was considerably improved compared to unfilled PMMA. This Algerian natural montmorillonite can serve as reinforcing nanofiller for polymer matrices and is of real interest for the fabrication of nanocomposite materials with improved properties. Copyright © 2009 Society of Chemical Industry [source]

Effects of organically modified clay loading on rate and extent of cure in an epoxy nanocomposite system

POLYMER INTERNATIONAL, Issue 11 2008
Sharon E Ingram
Abstract BACKGROUND: Cloisite 30B was added to diglycidyl ether of bisphenol F and cured with diaminodiphenylsulfone to investigate how the organoclay influenced the extent of cure. RESULTS: A substantial increase in the extent of cure was found with the addition of Cloisite 30B, when lower cure temperatures were employed. Cloisite 30B at 2 wt% resulted in a 40 °C increase in glass transition temperature and an increase in the magnitude of the bending modulus even though a high level of intercalated material was detected. CONCLUSIONS: It was observed that the addition of Cloisite 30B to the epoxy system increased the level of cure in the polymer, and was particularly prominent at low cure temperatures. Copyright © 2008 Society of Chemical Industry [source]

Properties of poly(ethylene terephthalate),poly(ethylene naphthalene 2,6-dicarboxylate) blends with montmorillonite clay

POLYMER INTERNATIONAL, Issue 12 2005
Antonio Sanchez-Solis
Abstract The production and properties of blends of poly(ethylene terephthalate) (PET) and poly(ethylene naphthalene 2,6-dicarboxylate) (PEN) with three modified clays are reported. Octadecylammonium chloride and maleic anhydride (MAH) are used to modify the surface of the montmorillonite,Na+ clay particles (clay,Na+) to produce clay,C18 and clay,MAH, respectively, before they are mixed with the PET/PEN system. The transesterification degree, hydrophobicity and the effect of the clays on the mechanical, rheological and thermal properties are analysed. The PET,PEN/clay,C18 system does not show any improvements in the mechanical properties, which is attributed to poor exfoliation. On the other hand, in the PET,PEN/clay,MAH blends, the modified clay restricts crystallization of the matrix, as evidenced in the low value of the crystallization enthalpy. The process-induced PET,PEN transesterification reaction is affected by the clay particles. Clay,C18 induces the largest proportion of naphthalate,ethylene,terephthalate (NET) blocks, as opposed to clay,Na+ which renders the lowest proportion. The clay readily incorporates in the bulk polymer, but receding contact-angle measurements reveal a small influence of the particles on the surface properties of the sample. The clay,Na+ blend shows a predominant solid-like behaviour, as evidenced by the magnitude of the storage modulus in the low-frequency range, which reflects a high entanglement density and a substantial degree of polymer,particle interactions. Copyright © 2005 Society of Chemical Industry [source]

Effect of termites on clay minerals in tropical soils: fungus-growing termites as weathering agents

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2002
P. Jouquet
Summary Termites of the subfamily Macrotermitinae play an important role in tropical ecosystems: they modify the soil's physical properties and thereby make food available for other organisms. Clay is important in the architecture of Macrotermitinae termite nests, and it has been postulated that termites could modify the mineralogical properties of some clays. We have tested this hypothesis of clay transformation by termites in the laboratory under controlled conditions, using Odontotermes nr. pauperans termite species, one of the main fungus-growing species at Lamto Research Station (Côte d'Ivoire). Soil handled by termites in nest building was saturated with SrCl2, glycol or KCl and afterwards heated at 250°C for X-ray diffraction analyses. Termite handling led to an increase in the expandable layers of the component clay minerals. Heating and saturation by potassium of modified clays did not close the newly formed expandable clay layers. However, differences occurred between parts of the constructions built by termites, and the clays can be ranked according to their degree of alteration in the following order: unhandled soils < galleries < chamber walls. Consequently, termites can be seen as weathering agents of clay minerals, as previously shown for micro-organisms and plants. [source]

Photopolymerization of clay/polyurethane nanocomposites induced by intercalated initiator

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007
Hailin Tan
Abstract An intercalated initiator was synthesized and used for preparation of clay/polyurethane nanocomposites by UV irradiation. Organoclays containing initiator groups were prepared by cationic exchange process which acted as both suitable intercalant and photoinitiator. These modified clays were then dispersed in the mixture of urethane acrylate and hexanediol diacrylate in different loading, then situ photopolymerized. Intercalated and exfoliated nanocomposite structure were evidenced by both X-ray diffraction spectroscopy and Transmission Electron Microscope. Thermal properties and morphologies of the resultant nanocomposites were also investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source]

Use of PP Grafted with Itaconic Acid as a New Compatibilizer for PP/Clay Nanocomposites

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2006
Edwin Moncada
Abstract Summary: Functionalized PP samples with different percentages of grafted IA, i.e., 0.7, 1 or 1.8 wt.-%, with similar molecular weights were used as compatibilizers in PP/clay nanocomposites. PP nanocomposites containing 1 wt.-% of organically modified clays, i.e., montmorillonite, natural hectorite and synthetic hectorite and 3 wt.-% of grafted PP with three different percentages of grafted IA as compatibilizers and two commercial PP samples of different molecular weights were prepared by melt blending. The nanocomposites were characterized by XRD, TEM and tensile mechanical measurements. It was found that the molecular weight of PP used as matrix as well as the percentage of grafted IA of the compatibilizer affected the degree of intercalation/exfoliation of the clay and consequently the mechanical properties of the nanocomposites. Values of 2,137 MPa for the modulus and 51 MPa for the tensile strength were obtained when natural hectorite was used and 2,117 and 40 MPa were obtained when montmorillonite was used. A comparative study was carried out, where PP grafted with maleic anhydride was used as the compatibilizer. Inferior mechanical properties were obtained for nanocomposites prepared by using this compatibilizer, where values of 1,607 MPa for the tensile modulus and 43 MPa for tensile strength were obtained. This result indicated that IA-grafted PP was far more efficient as compatibilizer for the formation of nanocomposites than commercially available maleic anhydride-grafted PP. Model showing interaction of the organically modified clay with grafted PP used as compatibilizer. [source]

Clay-PMMA Nanocomposites by Photoinitiated Radical Polymerization Using Intercalated Phenacyl Pyridinium Salt Initiators

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 9 2006
Alper Nese
Abstract Summary: In situ synthesis of poly(methyl methacrylate) (PMMA) nanocomposites by photopolymerization using organophilic montmorillonite (MMT) as the layered clay is reported. MMT clay was ion exchanged with N -phenacyl, N,N -dimethylanilinium hexafluoro phosphate (PDA) which acts as both suitable intercalant- and photo-initiator. These modified clays were then dispersed in methyl methacrylate (MMA) monomer in different loading degrees to carry out the in situ photopolymerization. Intercalation ability of the photoinitiator and exfoliated nanocomposite structure were evidenced by both X-ray diffraction (XRD) spectroscopy and transmission electron microscopy (TEM). Thermal properties and morphologies of the resultant nanocomposites were also studied. Schematic representation of clay-PMMA nanocomposites by photoinitiated radical polymerization. [source]

Effect of clay with different cation exchange capacity on the morphology and properties of poly(methyl methacrylate)/clay nanocomposites

POLYMER COMPOSITES, Issue 11 2009
Tsung-Yen Tsai
PMMA/clay nanocomposites were successfully prepared by in situ free-radical polymerization with the organic modified MMT-clay using methyl methacrylate monomer and benzoyl peroxide initiator. Two clays with different cation exchange capacity have been used to prepare and compare the several properties. The clays have been modified using Amphoterge K2 by ion exchange reaction to increase the compatibility between the clay and polymer matrices. The modified clays have been characterized by wide-angle X-ray diffraction pattern, Fourier transform infrared spectroscopy, and thermogravimetric analysis (TGA). The powdered X-ray diffraction and transmission electron microscopy techniques were employed to study the morphology of the PMMA/clay nanocomposites which indicate that the modified clays are dispersed in PMMA matrix to form both exfoliated and intercalated PMMA/modified clay nanocomposites. The thermomechanical properties were examined by TGA, differential scanning calorimetry, and dynamic mechanical analysis. Gas permeability analyzer shows the excellent gas barrier property of the nanocomposites, which is in good agreement with the morphology. The optical property was measured by UV,vis spectroscopy which shows that these materials have good optical clarity and UV resistance. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]

Functionalization of nanoclays with ionic liquids for polypropylene composites,

POLYMER COMPOSITES, Issue 5 2009
Jin Uk Ha
Cationic nanoclays were treated by ion exchange with various ionic liquids (ILs) containing cations and anions of different structure and/or molecular weight in order to investigate the effects of the IL structure and cation chain length on extent of clay dispersion, intercalation, and thermal stability. The modified clays containing imidazolium-, pyridinium-, and phosphonium-based cations were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. Although the thermal stability of pure ILs was mostly controlled by the type of the anion present, high temperature thermal stability of the modified clays, at the IL cation loadings achieved in this work, was not significantly dependent on type, structure, or size of the cation. The latter parameters, however, were of significant importance in controlling degree of dispersion of the nanoclays during melt compounding with polypropylene (PP). Basal spacing increased proportionally to the size and type of the intercalated cations and showed little change in the PP composites. Although commercial organoclays were shown to be less thermally stable than IL modified clays, they exhibited larger basal spacing and better dispersion characteristics in the polyolefin matrix; however, they increased to the same extent the thermal stability of the PP matrix as the phosphonium modified clays. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]

Effect of clay exfoliation and organic modification on morphological, dynamic mechanical, and thermal behavior of melt-compounded polyamide-6 nanocomposites

POLYMER COMPOSITES, Issue 2 2007
Smita Mohanty
Abstract Polyamide-6/clay nanocomposites were prepared employing melt bending or compounding technique followed by injection molding using different organically modified clays. X-ray diffraction and transmission electron microscopy were used to determine the molecular dispersion of the modified clays within the matrix polymer. Mechanical tests revealed an increase in tensile and flexural properties of the matrix polymer with the increase in clay loading from 0 to 5%. C30B/polyamide-6 nanocomposites exhibited optimum mechanical performance at 5% clay loading. Storage modulus of polyamide-6 also increased in the nanocomposites, indicating an increase in the stiffness of the matrix polymer with the addition of nanoclays. Furthermore, water absorption studies confirmed comparatively lesser tendency of water uptake in these nanocomposites. HDT of the virgin matrix increased substantially with the addition of organically modified clays. DSC measurements revealed both , and , transitions in the matrix polymer as well as in the nanocomposites. The crystallization temperature (Tc) exhibited an increase in case of C30B/polyamide-6 nanocomposites. Thermal stability of virgin polyamide-6 and the nanocomposites has been investigated employing thermogravimetric analysis. POLYM. COMPOS., 28:153,162, 2007. © 2007 Society of Plastics Engineers [source]