Incorporation Of Clay Research Articles

Rheological behaviour of acrylate/montmorillonite nanocomposite latexes and their application in leather finishing as binders

The paper describes the rheological behaviour of nanocomposite latexes based on butylacrylate–co-methylmethacrylate–co-acrylamide terpolymers including various commercial nanoclays obtained via in situ emulsion polymerization. Rotational, oscillatory, emulsion stability and thixotropy tests (recovery) were performed to evaluate the influence of clay incorporation, type of clay and also emulsifier content in the composition of these nanomaterials. It was observed that the viscosities of the nanocomposite latexes were increased by clay incorporation at low shear rates, while a shear thinning effect was observed at higher shear rates. Oscillatory tests indicated a dominant elastic behaviour and high physical stabilities for all the nanocomposites. The hydrophobic character of the clay and emulsifier content also influenced the viscosity and dynamic modulus of the emulsions.The nanocomposite latexes were tested for leather finishing as polymeric binders. Results showed that the finish performance of the leather surfaces was improved by clay incorporation. It was also concluded that for coating applications it is important to find a balance between the compatibility of the nanoclay type with the polymer and the emulsifier amount necessary for emulsion stabilization which both influence the rheology and the final performance of the coatings.

Nanoclay‐reinforced, polypropylene‐based wood–plastic composites

AbstractWood plastic composites (WPCs) are a new class of materials which combine the characteristics of plastic and wood. In appearance, they are similar to wood, but the low stiffness of plastics makes the composite modulus significantly lower than that of solid wood. Increasing the wood content in the WPCs can improve stiffness, but the rate of water absorption also goes up. Here, nanoclay was compounded with wood and plastic using a twin screw extruder to form a three‐component composite to improve the stiffness of WPCs. To overcome the previously observed reduction in strength and increase in the rate of water absorption, different compounding procedures were used. It was found that pre‐compounding wood flour with polymer followed by incorporation of clay in a second step resulted in an increase in stiffness, retention in strength, and a reduction in the rate of water absorption. Thus, adding nanoclays is an alternative for increasing properties instead of adding extra wood flour to a concentration in excess of 55 wt% as this involves processing difficulties. POLYM. ENG. SCI., 50:2013–2020, 2010. © 2010 Society of Plastics Engineers

Preparation and Characterization of an Alginate/Clay Nanocomposite for Optoelectronic Application

Sodium Alginate/bentonite clay composites of different compositions were prepared by solution casting method. The electrical properties (Conductivity, Dielectric constant) of the composites were investigated by standard methods with Impedance Analyzer. The electrical properties were found to improve with the incorporation of bentonite clay. The thermal, physical and mechanical properties of sodium alginate/bentonite clay composite were investigated by Thermo-Mechanical Analyzer (TMA), X-ray Deffraction (XRD), and Universal Testing Machine respectively. . Tensile Strength (TS) and Elongation at break (Eb) of 2% clay containing composite film were found to be 7.6 MPa and 55% respectively. The XRD demonstrates the enhancing crystallinity of sodium alginate/bentonite clay composite with the increasing clay content. TMA results showed a higher thermal stability in the composite. Water absorption properties of the sodium alginate/clay composite were studied and found to decrease with the increase of clay content. . The inter action between sodium alginate and bentonite clay were studied by Fourier transform infrared spectroscopy (FT-IR). All of the results indicate that the developed composite is promising for use in a wide variety of optoelectronic applications.

Preparation of fire-resistant poly(styrene-co-acrylonitrile) foams using supercritical CO2 technology

This work deals with the preparation and characterization of fire-resistant poly(styrene-co-acrylonitrile) (SAN) foams containing (organo)clays and/or melamine polyphosphate (MPP) as fire retardants using supercritical CO2 as the foaming agent. The additives dispersion was first characterized with X-ray and transmission electron microscopy (TEM) analyses. Their presence clearly affected the cellular morphology, as observed by scanning electron microscopy (SEM). Then, the peak of heat release rate (PHRR) and total heat evolved (THE) were determined with a cone calorimetry test, performed on each foamed sample as a function of the foam density. Incorporation of clay (3 and 5 wt%) in the exfoliated state into the SAN foam clearly led to a significant decrease of PHRR, while intercalated and aggregated clay had a lower effect. Similar results were obtained with 10 and 20 wt% of MPP. The best results were obtained when exfoliated clay and MPP were combined, with a PHRR drop as large as 75%, thanks to the synergistic action of both additives. The magnitude of PHRR drop, related to the fire resistance, was found to be in direct relationship with the cohesiveness of the protective carbonaceous layer formed at the sample surface during combustion. Clay and MPP, when added together, are thus believed to favour the formation of a highly cohesive protective layer able to act as an efficient shield against the flame, despite the fact that the sample is originally composed of ∼90% of voids.

Controlled release of thiram from neem-alginate-clay based delivery systems to manage environmental and health hazards

The release of pesticides from the controlled release formulations is the best strategy to reduce the agro-environmental pollution. The present study deals with the synthesis of pesticide delivery devices based on neem leaf powder (NLP) and kaolin and bentonite. The beads of different compositions were prepared by varying the amount of clays. These beads were characterized by FTIR, SEMs, EDAX, TGA and swelling study. Formulation characteristics like entrapment efficiency, bead size, percentage equilibrium swelling of the beads and diffusion mechanism for the release of thiram have been evaluated. The incorporation of clays in beads has controlled the release of thiram from the formulations. The release occurred through non-Fickian diffusion mechanism.

Synthesis and Characterization of Aliphatic-aromatic Random Copolyester/clay Nano-biocomposites

Aliphatic-aromatic biodegradable random copolyester, poly (butylene sebacate-co-butylene isophthalate) (PBSeI) was synthesized by a two step direct melt polycondensation method. This copolyester was characterized by solubility studies, viscosity measurements, infrared, 1H-NMR, 13C-NMR and thermal data. However, to be a real alternative to classical synthetic polymers and find applications, the thermal properties of biodegradable polymers have to be improved. Synthesis of nano-biocomposites, which are obtained by incorporation of nanofillers into a biomatrix, is an interesting way to create polymers with characteristic properties. In the present study, the nano-biocomposites were synthesized by dispersing different weight percentages (1, 3 and 5%) of organo-modified montmorillonite clay (OMMT) into the biodegradable polyester matrix by the solvent intercalation method. Structural characterization and thermal analysis were carried out to better understand, the relationship between the structuring of the nanofillers and the properties of nano-biocomposites. The X-ray diffraction patterns obtained for the systems confirmed the nanodispersion of the OMMT-clay in the polyester networks. The scanning electron microscopy and high resolution transmission electron microscopy analyses showed that there was no phase separation between the two components which confirmed the compatibility of polyester with the organo-modified clay system. The results show that clay incorporation improved the thermal properties of PBSeI due to the exfoliated structure of the nanocomposites formed, and thus may increase the applicability of this biodegradable polymer in different fields.

Fluorescence Resonance Energy Transfer between organic dyes adsorbed onto nano-clay and Langmuir–Blodgett (LB) films

In this communication we investigate two dyes N, N′-dioctadecyl thiacyanine perchlorate (NK) and octadecyl rhodamine B chloride (RhB) in Langmuir and Langmuir–Blodgett (LB) films with or with out a synthetic clay laponite. Observed changes in isotherms of RhB in absence and presence of nano-clay platelets indicate the incorporation of clay platelets onto RhB-clay hybrid films. AFM images confirm the incorporation of clay into hybrid films. FRET is observed in clay dispersion and LB films with and without clay. Efficiency of energy transfer is maximum in LB films with clay.

Influence of Clay Addition on Physical Properties and Wettability of Peat-growing Media

The role of clay incorporation on the physical properties and wettability of peat-growing media was assessed from water retention curves and from contact angle and water drop penetration time measurements, respectively. Two peat substrates presenting different degrees of decomposition (weakly and highly decomposed Sphagnum peat) were used and mixed with clay in the form of powder with a peat:clay ratio of 90:10 (by vol.). Results indicated relatively little change in water retention resulting from clay incorporation in the peat-growing media tested. On the other hand, they showed a significant improvement of the wettability of both substrates in the driest conditions when peat-growing media presented a pronounced hydrophobic character, whereas the wettability of materials was not changed in the wettest conditions when they were largely hydrophilic. The influence of the degree of peat decomposition was also observed with somewhat higher wettability for the weakly decomposed peat:clay mixture than for the highly decomposed peat:clay mixture. Because the hydrophobic character of highly decomposed peat is more pronounced and appears at a higher water content than weakly decomposed peat, the effect of clay addition also appears at higher water contents for highly decomposed peat. Incorporating clay into peat-growing media should be considered for its ability to improve the wettability of growing media with a hydrophobic character (i.e., to improve the ability of the growing media to be rewetted) rather than only its ability to influence the water retention characteristics of the growing media.

Microcellular Foaming of Polypropylene/Clay Nanocomposites with Supercritical Carbon Dioxide

The solid-state foaming of two series of polypropylene (PP)/clay nanocomposites based on two different types of organoclays were studied. The wide-angle X-ray diffraction results showed that a supercritical carbon dioxide (scCO 2) saturation process could lead to the further exfoliation of clay when the initial interlayer spacing was larger enough. It was found that the incorporation of clays exerted significant impacts on cell nucleation and growth and the effect of clays was determined by their dispersion state. However, the influence of clay on the foaming of the PP/clay nanocomposites became marginal at a higher saturation pressure and a lower foaming temperature.

Morphology, biodegradability, mechanical, and thermal properties of nanocomposite films based on PLA and plasticized PLA

AbstractIn this study, melt intercalation method is applied to prepare poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG)‐plasticized PLA nanocomposite films including 0, 3, and 5% organoclay (Cloisite 30B) using a laboratory scale compounder, which is connected to a microcast film device. To evaluate the nanomorphology and the dispersion state of the clays, X‐ray diffraction (XRD) and transmission electron microscopy (TEM) are conducted. Tensile tests are performed to characterize the mechanical behavior of the films. Biodegradation rate is determined by degradation tests in composting medium. Differential scanning calorimeter (DSC) is applied to observe the thermal behavior of the films. XRD and TEM show that the exfoliation predominantly occurrs in plasticized PLA nanocomposites, whereas unexfoliated agglomerates together with exfoliated clays are observed in the nonplasticized PLA. Tensile tests indicate that the addition of 3% clay to the neat‐PLA does not affect the strength; however, it enhances the modulus of the nanocomposites in comparison to neat‐PLA. Incorporation of 3% clay to the plasticized PLA improves the modulus with respect to PLA/PEG; on the other hand, the strain at break value is lowered ∼ 40%. The increase in the rate of biodegradation in composting medium is found as in the order of PLA > PLA/PEG > 3% Clay/PLA/PEG > 5% Clay/PLA/PEG > 3% Clay/PLA. DSC analysis shows that the addition of 3% clay to the neat PLA results in an increase in Tg. The addition of 20% PEG as a plasticizer to the neat‐PLA decreases Tg about 30°C, however incorporation of clays increases Tg by 4°C for the plasticized PLA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

The influence of organophilic clay on field electron emission uniformity and lifetime of screen printed carbon nanotube film

The effect of adding clay, modified by a silane coupling agent, into the carbon nanotube (CNT) paste on the field electron emission and a lifetime of screen printed CNT film was studied. The composition of organophilic clay and CNTs was characterized by a combination of X-ray diffraction, and scanning electron microscopy. The incorporation of clay improved the dispersivity, adhesiveness, and conductive networking of paste, therewith enhancing the field emission's uniformity and stability. The improvement of this gas barrier on the CNT film by clay loading prevents emission degradation.

A Study of Dynamic Mechanical and Thermal Behavior of Starch/Poly(vinylalcohol) Based Films

Starch/Poly(vinylalcohol) blends in two different ratios (60:40 and 50:50) were prepared with glycerol as a plasticizer. Films were cast by a solution casting method. One set of films were filled with 10 wt% of bentonite clay and another set of films were crosslinked with epichlorohydrin in an alkaline medium. The prepared film samples were characterized with dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). The presence of clay and crosslinking with epichlorohydrin was found to have considerable effect on the dynamic mechanical properties and thermal stability of the films. Intercomponent H-bonding between starch, Poly(vinylalcohol) and glycerol enhanced the thermal stability of the films. But incorporation of clay and crosslinking with epichlorohydrin enhanced the steric crowding and lowered the thermal stability of the films.

Chitosan/clay films' properties as affected by biopolymer and clay micro/nanoparticles' concentrations

Blends of chitosan (from Cuban lobster) and clay micro/nanoparticles were prepared by dispersion of the clay particles in the film matrix and the films obtained were characterized in terms of water solubility, water vapor, oxygen and carbon dioxide permeability, optical, mechanical and thermal properties using an Instron universal testing machine, differential scanning calorimetry, thermogravimetric analyses and scanning electron microscopy ( SEM). The water vapor barrier properties of the films were significantly improved by incorporation of clay in their composition, while the water solubility decreased as the clay concentration increased (for a constant chitosan concentration). The tensile strength of chitosan/clay films increased significantly with increasing chitosan and clay concentrations, while the values of elongation decreased slightly for high values of chitosan concentration. T m increased with the increase of chitosan concentration, but the changes in T m with the addition of clay were not significant. Polynomial models were fitted to the experimental data in order to facilitate future design of chitosan/clay film systems.

Studies on aliphatic -aromatic random copolyester- based nano-biocomposite materials

Aliphatic-aromatic biodegradable random copolyester, poly (butylene succinate-co-butylene isophthalate) PBSI was synthesised by a two step direct melt polycondensation method. This copolyester was characterised by solubility, viscosity measurements, IR, 1 H NMR, 13 C NMR and thermal studies. But, to be a real alternative to classical synthetic polymers and find applications, biodegradable polymer properties have to be enhanced. Synthesis of nano-biocomposites, which are obtained by incorporation of nanofillers into a biomatrix, is an interesting way to achieve the polymers with characteristic property. In present study, the nano- biocomposites were synthesised by dispersing different weight percentage (1, 3 and 5 %) of organo modified montmorillonite clay (OMMT) into the biodegradable polyester matrix by solvent intercalation method. The structural characterisation and thermal analysis have been carried out to understand better the relationship between the nanofillers structuring and the properties of nano-biocomposites. The X-ray diffraction patterns obtained for the systems confirmed the nanodispersion of OMMT-clay in the polyester networks. The results show that the clay incorporation and the obtained structures enhanced the thermal properties of PBSI, and thus may increase the applicability of this biodegradable polymer in different fields.

Studies on aliphatic -aromatic random copolyester- based nano-biocomposite materials

Aliphatic-aromatic biodegradable random copolyester, poly (butylene succinate-co-butylene isophthalate) PBSI was synthesised by a two step direct melt polycondensation method. This copolyester was characterised by solubility, viscosity measurements, IR, 1 H NMR, 13C NMR and thermal studies. But, to be a real alternative to classical synthetic polymers and find applications, biodegradable polymer properties have to be enhanced. Synthesis of nano–biocomposites, which are obtained by incorporation of nanofillers into a biomatrix, is an interesting way to achieve the polymers with characteristic property. In present study, the nano- biocomposites were synthesised by dispersing different weight percentage (1, 3 and 5 %) of organo modified montmorillonite clay (OMMT) into the biodegradable polyester matrix by solvent intercalation method. The structural characterisation and thermal analysis have been carried out to understand better the relationship between the nanofillers structuring and the properties of nano-biocomposites. The X-ray diffraction patterns obtained for the systems confirmed the nanodispersion of OMMT-clay in the polyester networks. The results show that the clay incorporation and the obtained structures enhanced the thermal properties of PBSI, and thus may increase the applicability of this biodegradable polymer in different fields. Keywords: Nano- biocomposites, biodegradable, montmorillonite clay, aliphatic-aromatic random copolyesters.

Processing techniques for bio-based unsaturated-polyester/clay nanocomposites: Tensile properties, efficiency, and limits

Bio-based clay/polymer nanocomposites using blends of styrene-based unsaturated polyester and epoxidized methyl soyate were manufactured using solvent-based processing techniques. Four methods were evaluated to assess limitations related to solvent removal and incorporation of high clay and bio-resin content. Nanocomposite characterization was performed using electron microscopy and tensile tests. Solvent type, bio-resin addition sequence, and sonication energy were the key parameters governing processing efficiency and composite quality. Processes with bio-resin added after solvent removal show promise for the incorporation of high bio-resin and nanoclay contents. Use of acetone as a solvent with bio-resin added after solvent removal led to nanocomposites with good nanoclay dispersion and exfoliation, and high tensile modulus. Direct sonication in the base resin diluted with styrene led to enhanced and balanced gains in stiffness and toughness.

Bio-based Polyurethane-clay Nanocomposite Foams: Systheses and Properties

AbstractStarting from a bio-based polyol through modification of soybean oil, BIOH™ X-210, two series of bio-based polyurethanes-clay nanocomposite foams have been prepared. The effects of organically-modified clay types and loadings on foam morphology, cell structure, and the mechanical and thermal properties of these bio-based polyurethanes-clay nanocomposite foams have been studied with optical microscopy, compression test, thermal conductivity, DMA and TGA characterization. Density of nanocomposite foams decreases with the increase of clay loadings, while reduced 10% compressive stress and yield stress keep constant up to 2.5% clay loading in polyol. The friability of rigid polyurethane-clay nanocomposite foams is high than that of foam without clay, and the friability for nanofoams from Cloisite® 10A is higher than that from 30B at the same clay loadings. The incorporation of clay nanoplatelets decreases the cell size in nanocomposite foams, meanwhile increases the cell density; which would be helpful in terms of improving thermal insulation properties. All the nanocomposite foams were characterized by increased closed cell content compared with the control foam from X-210 without clay, suggesting the potential to improve thermal insulation of rigid polyurethane foams by utilizing organically modified clay. Incorporation of clay into rigid polyurethane foams results in the increase in glass transition temperature: the Tg increased from 186 to 197 to 204 °C when 30B concentration in X-210 increased from 0 to 0.5 to 2.5%, respectively. Even though the thermal conductivity of nanocomposite foams from 30B is lower than or equal to that of rigid polyurethane control foam from X-210, thermal conductivity of nanocomposite foams from 10A is higher than that of control at all 10A concentrations. The reason for this abnormal phenomenon is not clear at this moment; investigation on this is on progress.

Epoxy Nanocomposites Based on High Temperature Pyridinium-Modified Clays

Polymer/clay nanocomposites are generally fabricated by thermal curing or melt compounding at elevated temperatures, however the thermal stability of common alkyl ammonium treated clays is poor and decomposition occurs inevitably during high temperature processing. In this study, we modified clays with an aromatic pyridinium salt. Thermogravimetric analysis (TGA) showed that the onset degradation temperature (Td(onset)) and maximum decomposition temperature (Td(max)) of the pyridinium treatment clays was up to 310 and 457 degrees C respectively implying high thermal stability. The thermal decomposition behaviour of the pyridinium modified clays was discussed. A series of epoxy/clay nanocomposites were synthesized using a diglycidyl ether of bisphenol A (DGEBA) epoxy and diethyltoluene diamine (DETDA). The morphology of epoxy/clay nanocomposites was characterized with wide angle X-ray diffraction (WAXD) and transmission electron microscope (TEM), and intercalated structures were observed. The storage modulus of epoxy was increased but glass transition temperature was decreased with clay incorporation. The effects of clays on glass transition temperature (Tg) of epoxy were also discussed.

Structure and properties of poly(ethylene oxide)‐organo clay nanocomposite prepared via melt mixing

AbstractPoly(ethylene oxide) (PEO)/organo clay nanocomposites were prepared by melt‐mixing using a laboratory kneader followed by compression molding. The nanocomposites were characterized by X‐ray diffraction, atomic force microscopy, and scanning electron microscopy. Their crystallization behavior in hot stage was investigated by polarized optical microscopy (POM). A decrease in size and regularity were observed as a result of incorporation of clay into the PEO matrix. The dynamic viscoelastic behavior of PEO/organo clay nanocomposites was assessed using a strain‐controlled parallel plate rheometer. The effects of clay concentration and the processing temperature on the rheological properties of the nanocomposites were extensively studied. A significant increase in the viscosity and storage modulus of the nanocomposites was found with the increasing clay content. The flow activation energy decreased with the incorporation of clay. The reinforcing effect of the organoclay was determined in dynamic mechanical analysis and tensile testing. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers

Preparation and characterization of polyethylene (PE)/clay nanocomposites by in situ polymerization with vanadium-based intercalation catalyst

Complete exfoliation of clay during vanadium-based Zigler-Natta polymerization of ethylene has been successfully carried out by using clay and MgCl2 hybrid supports. MgCl2 offers catalyst loading sites, and the vanadium catalyst is avoided directly anchoring in the surface of the clay, so intercalation catalyst clay/MgCl2/VOCl3displays high activity for ethylene polymerization. Exfoliated PE/clay nanocomposites are confirmed by X-ray diffraction (XRD), and transmission electron microscopy (TEM). Strong interaction between the dispersed clay particles and the polymer matrices provides good thermal and mechanical properties. Compared with pure PE, all these nanocomposites show enhancement of the melting temperature (Tm) and the thermal decomposition temperatures. Additionally, the incorporation of clay into the PE matrix significantly improves the mechanical properties of these nanocomposites. The increased tensile strength has been observed in the range of 3.4 to 7.9 MPa. The tensile moduli of the PE/clay nanocomposite are 23.4%-45.3% higher than that of the pure PE.