Clay Nanocomposites Research Articles

Erratum to: Vinyl Modified Cloisite 30B Clay as an Efficient Filler for the Synthesis of Poly(styrene-co-butyl acrylate)/Clay Nanocomposite by Emulsion Polymerization

Erratum to: Vinyl Modified Cloisite 30B Clay as an Efficient Filler for the Synthesis of Poly(styrene-co-butyl acrylate)/Clay Nanocomposite by Emulsion Polymerization

Cotton waste and nanoclay‐based phenolic novolac epoxy composites and evaluation of their properties

AbstractIn this study, two types of biobased epoxy composites were prepared by using only alkali‐treated cotton waste (CtW), or with the nanoclay (NC) in the form of hybrid reinforcement. Phenol novolac‐type epoxy resin (EPN) was used as a matrix. Untreated (CtW) and alkali‐treated (NaOH‐CtW) particles were characterized by scanning electron microscopy (SEM)/energy‐dispersive X‐ray spectroscopy (EDX). The average size for NC was determined as 3838 nm. Composites were prepared at 10–50 wt% NaOH‐CtW and 20 wt% NaOH‐CtW/(1–2–3–4–5) wt% NC ratios. The morphology of the composites was investigated using SEM. The composites' properties were determined by applying thermogravimetric analysis (TGA), and various tests (tensile, hardness, water sorption, and surface contact angle measurement). The tensile strength of pure EPN was 96.6 MPa, while it changed in the range of 74–98 and 81–106 MPa for NaOH‐CtW and hybrid composites, respectively. All hybrid composites exhibited higher Young's modulus values (7.7–8.9 GPa). Thermal values of hybrid composites were found higher and their char percentages varied in the range of 28.9–30.3%. NaOH‐CtW increased the water sorption of the epoxy matrix from 0.59% up to 6% by 50 wt%. In contrast, a decrease in water sorption of NC composites was observed.

Evaluation of mechanical and tribological properties of nano clay reinforced Kevlar/Sisal polyester composites

AbstractDue to the material's balance of mechanical and ecological features, hybrid composites have become a hot topic among researchers. Hybridization is a helpful process for improving the strength and performance of composite materials. Hybrid composites were created in this study by reinforcing Kevlar(K)/Sisal(S) in Polyester using a hand lay‐up method with various wt% (2,4,6 wt%) of Nano clay (NC) reinforcements. Mechanical experiments were performed on hybrid composite laminates to establish their tensile and flexural properties, and SEM was used to characterize the fractured samples. The fabricated specimens were also subjected to erosion tests, conducted at ambient temperature with an elongated silica sand erodent striking at 148 m/s at impingement angles of 30, 60, and 90°. In comparison to 0–4 wt% NC reinforcement, the tensile strength increased by 18% for the polyester/KSSK composites. Flexural strength is highest at 2 wt%, while polyester/KSSK reinforced NC composites have a 28% improvement in flexural strength compared to 0–2 wt%. The erosion wear resistance of 2 wt% NC reinforced KSSK/polyester was excellent in the normal direction, with minor wear at a 90° impingement angle. This conclusion supports the suggested new laminates' suitability for engineering materials in the aviation and automobile industry.

Polystyrene-Sepiolite Clay Nanocomposites with Enhanced Mechanical and Thermal Properties.

Polystyrene (PS)/sepiolite clay nanocomposites were prepared via the melt extrusion technique using vinyl tri-ethoxy silane (VTES) as the compatibilizer and cross-linking agent. Mechanical, thermal, and flame-retardant properties of the newly developed polystyrene-based nanocomposites were determined. Surface morphology was investigated using scanning electron microscopy (SEM), examining the distribution of the filler in various compositions of fabricated composites. Structural analysis of the samples was carried out using the Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. Thermal stability was determined by thermal gravimetric analysis (TGA), showing a maximum 30.2 wt.% increase in residue by adding sepiolite clay. The results obtained from the dynamic mechanical analyzer (DMA) in terms of the storage modulus, loss modulus and damping factor exhibited better stress transfer rate and effective interfacial adhesion between the filler and the matrix. The higher filler loaded sample showed greater flame retardancy by decreasing the burning rate up to 48%.

Improving the Thermal Behavior and Flame-Retardant Properties of Poly(o-anisidine)/MMT Nanocomposites Incorporated with Poly(o-anisidine) and Clay Nanofiller.

The synthesis of MMT and poly(o-anisidine) (MMT/POA) clay nanocomposites was carried out by using the chemical oxidative polymerization of POA and MMT clay with POA, respectively. By maintaining the constant concentration of POA, different percentage loads of MMT clay were used to determine the effect of MMT clay on the properties of POA. The interaction between POA and MMT clay was investigated by FTIR spectroscopy, and, to reveal the complete compactness and homogeneous distribution of MMT clay in POA, were assessed by using scanning-electron-microscope (SEM) analysis. The UV–visible spectrum was studied for the optical and absorbance properties of MMT/POA ceramic nanocomposites. Furthermore, the horizontal burning test (HBT) demonstrated that clay nanofillers inhibit POA combustion.

Nanoclay biopolymer composites: Synthesis, characterization and nitrogen release under controlled conditions

As the production sector of N fertilizer challenged by energy crisis of the world and consumption sector is challenged by the environmental impacts, there is an urgent need to improve the nitrogen use efficiency for the sustainable growth of agriculture sector. The controlled release/ slow-release N fertilizers are smart choices to serve this purpose. So, this manuscript aims to synthesise nano clay bio-polymer composites (NCBPC) and using it for controlled N release. Nano clay bio-polymer composites were prepared by aqueous copolymerization of acrylic acid with acrylamide in presence of bentonite nano clay and starch as a partial replacement for synthetic polymers. Maize and wheat flour (maida) were used as starch source at 20 and 30% replacement level to synthesise different NCBPC products. The resulting products were characterized using FTIR and SEM which revealed the participation of bentonite and starch in the polymerization reaction at the nano level. The incubation study in soil disclosed the slow-release of nitrogen by these materials. Therefore, bentonite clay with cereal grain flours may be used for the synthesis of nano clay bio-polymer composites for slow-release of nitrogen.

Nanoclay biopolymer composites: Synthesis, characterization and nitrogen release under controlled conditions

As the production sector of N fertilizer challenged by energy crisis of the world and consumption sector is challenged by the environmental impacts, there is an urgent need to improve the nitrogen use efficiency for the sustainable growth of agriculture sector. The controlled release/ slow-release N fertilizers are smart choices to serve this purpose. So, this manuscript aims to synthesise nano clay bio-polymer composites (NCBPC) and using it for controlled N release. Nano clay bio-polymer composites were prepared by aqueous copolymerization of acrylic acid with acrylamide in presence of bentonite nano clay and starch as a partial replacement for synthetic polymers. Maize and wheat flour (maida) were used as starch source at 20 and 30% replacement level to synthesise different NCBPC products. The resulting products were characterized using FTIR and SEM which revealed the participation of bentonite and starch in the polymerization reaction at the nano level. The incubation study in soil disclosed the slow-release of nitrogen by these materials. Therefore, bentonite clay with cereal grain flours may be used for the synthesis of nano clay bio-polymer composites for slow-release of nitrogen.

Progressive Intercalation and Exfoliation of Clay in Polyaniline–Montmorillonite Clay Nanocomposites and Implication to Nanocomposite Impedance

Conducting polymers, such as polyaniline (PANi) and polypyrrole (PPy), and their nanocomposites, are desired in a wide range of applications, including supercapacitors, lithium ion battery, chemical sensors, biosensors, barrier thin films, and coatings, because of their interesting electrical and electrochemical properties. It is well known that the properties of polymer nanocomposites depend on their chemical structure, as well as their microstructure, yet scientists and engineers have not fully understood how to properly control the structure of polymer nanocomposites. In this study, it is shown that the structure of polyaniline–montmorillonite clay nanocomposites (PACN) can be controlled by varying the ammonium persulfate (APS, oxidant) concentration. The structure of polyaniline and Cloisite 20A clay are, therefore, profoundly affected during the synthesis of PACN nanocomposites. The thickness of polyaniline crystal decreased with increasing oxidant concentration. Fourier transform infrared spectroscopy (FTIR) was used to determine the oxidation state of PANi. The structure of the nanocomposites was studied by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), wide-angle X-ray diffraction (WAXD), wide-angle X-ray scattering (WAXS), and small-angle X-ray scattering (SAXS). Electrochemical impedance spectroscopy (EIS) analysis of polyimide nanocomposite coatings containing PACN with varying levels of intercalation and exfoliation indicate that the coating impedance decreased with exposure time for some coating systems. It is shown that polyimide–PACN nanocomposite coating containing highly intercalated clay was more durable and maintained constant impedance after 20 weeks of exposure in a corrosive medium.

Co-Precipitation Synthesis of Clay-Magnetite Nanocomposite for Adsorptive Removal of Synthetic Dye in Wastewater of Benang Bintik Batik

Clay is a natural material that has been widely applied as a low-cost adsorbent for removing various contaminants from wastewater. To improve its characteristics and activity, natural clay from Central Kalimantan was activated by acid and calcination treatments, then synthesized with magnetite (Fe3O4) in nanocomposite by co-precipitation method. The obtained nanocomposite was further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, nitrogen adsorption, vibrating sample magnetometry, and transmission electron microscopy methods. The results showed that co-precipitation method has been successfully produced clay-magnetite nanocomposite from activated clay with specific surface area, saturation magnetization, and particle size were 37.458 m2/g, 24.910 emu/g, and 50 nm, respectively. The obtained natural clay, activated clay, and clay-magnetite nanocomposite were then evaluated for adsorptive removal of naphthol blue black (NBB) synthetic dye from wastewater generated by an industry of Benang Bintik batik in Central Kalimantan using a batch system. The results showed that optimum pH for adsorptive removal process from these adsorbents were 2, while the optimum contact times of natural clay, activated clay, and clay-magnetite nanocomposite were 90, 60, and 60 minutes, respectively. The clay-magnetite nanocomposite also showed a much better removal efficiency (99.58%) than activated clay (86.28%) and natural clay (68.27%). The utilization of clay-magnetite nanocomposite as adsorbent not only can increase its removal efficiency against NBB dye, but also can facilitate the separation of the adsorbent solid phase from wastewater using an external magnetic field after the adsorptive removal process.

Synthesis and Characterization of Copolymers and Nanocomposites from Limonene, Styrene and Organomodified-Clay Using Ultrasonic Assisted Method.

In the present work, we report a simple synthesis method for preparation of copolymers and nanocomposites from limonene and styrene using clay as a catalyst. The copolymerization reaction is carried out by using a proton exchanged clay as a catalyst called Mag-H+. The effect of temperature, reaction time and amount of catalyst were studied, and the obtained copolymer structure (lim-co-sty) is characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H-NMR) and differential scanning calorimetry (DSC). The molecular weight of the obtained copolymer is determined by gel permeation chromatography (GPC) and is about 4500 g·mol−1. The (lim-co-sty/Mag 1%, 3%, 7% and 10% by weight of clay) nanocomposites were prepared through polymer/clay mixture in solution method using ultrasonic irradiation, in the presence of Mag-CTA+ as green nano-reinforcing filler. The Mag-CTA+ is organophilic silicate clay prepared through a direct exchange process, using cetyltrimethylammonuim bromide (CTAB). The prepared lim-co-sty/Mag nanocomposites have been extensively characterized by FT-IR spectroscopy, X-ray diffraction (XRD), scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM). TEM analysis confirms the results obtained by XRD and clearly show that the obtained nanocomposites are partially exfoliated for the lower amount of clay (1% and 3% wt) and intercalated for higher amounts of clay (7% and 10% wt). Moreover, thermogravimetric analysis (TGA) indicated an enhancement of thermal stability of nanocomposites compared with the pure copolymer.

Design and development of montmorillonite-sodium alginate microbeads for oral sustained delivery of cefaclor

Drug administration via oral route is most suitable for drug delivery to patients. But this route is associated with several drawbacks such as high frequency of administration as well as gastric discomfort. To avoid these problems attempt was made to develop the sustained release system by using nanocomposite clay (MMT) and polymer (Na-Al) based microbeads for oral administration of CFR. The formulations were optimized and validated by using Box–Behnken design with 3 different levels of MMT, Na-Al and CaCl2 wherein the %EE and % drug release at 8 h were considered as dependent responses. The developed formulation was characterized by FT-IR, DSC as well as XRD. The optimized formulation was evaluated for % yield, swelling behavior, particle size, drug release and surface morphology by FESEM. The developed formulation showed physical interaction due to surface adsorption and intercalation of drug with that of MMT. The optimized formulation showed high yield, %EE and swelling behavior due to high amount of MMT and Na-Al. The particle size of the microbeads was below 500 µm and drug release takes place in sustained manner up to 12 h. Polymeric cross-linking and MMT stalking were observed in FESEM study indicated distinctive system. Drug release follow the non-fickian diffusion pattern coupled with matrix release as indicated by Korsemeyer-Peppas (n) value 0.72.

Influence of organically modified clays on the barrier properties of bromo butyl rubber composites for tyre inner liner application

ABSTRACT The barrier and mechanical properties are the primary requirement of a rubber for tyre inner liner application that can be fulfilled by incorporation of organically modified clay (OMC) into rubber matrix. In this work, functional rubber composites with an improved gas barrier performance were prepared using bromobutyl rubber (BIIR) and natural rubber (NR) as the elastomer phases, and OMC and carbon black (CB) as the functional fillers by employing standard solid-state mixing and vulcanization methods. CB was partially replaced by OMC to achieve adequate barrier and mechanical properties. OMC modified composite showed ~35% improvement in the barrier properties as compared to the control compound (60 phr carbon black, 10 phr NR and 90 phr of BIIR loaded rubber compound). The dispersion of the nano clays were investigated by transmission electron microscopic (TEM), scanning electron microscopic (SEM) and X-ray diffraction (XRD) studies. The XRD study revealed that higher d- spacing and crystalinity of the nano clay composites ease the exfoliation tendency. The mechanical properties of the clay filled nano composites, such as hardness tensile strength, modulus and air barrier properties were superior to the control compound. The developed BIIR/nanoclay composites with improved barrier properties prepared by conventional mixing method in line with common industrial practice can be used in rubber products such as tire inner liner.

Review of Clay-Based Nanocomposites as Adsorbents for the Removal of Heavy Metals

Due to rapid industrialization, urbanization, and surge in modern human activities, water contamination is a major threat to humanity globally. Contaminants ranging from organic compounds, dyes, to inorganic heavy metals have been of major concern in recent years. This necessitates the development of affordable water remediation technologies to improve water quality. There is a growing interest in nanotechnology recently because of its application in eco-friendly, cost-effective, and durable material production. This study presents a review of recent nanocomposite technologies based on clay, applied in the removal of heavy metals from wastewater, and highlights the shortcomings of existing methods. Recently published reports, articles, and papers on clay-based nanocomposites for the removal of heavy metals have been reviewed. Currently, the most common methods utilized in the removal of heavy metals are reverse osmosis, electrodialysis, ion exchange, and activated carbon. These methods, however, suffer major shortcomings such as inefficiency when trace amounts of contaminant are involved, uneconomical costs of operation and maintenance, and production of contaminated sludge. The abundance of clay on the Earth’s surface and the ease of modification to improve adsorption capabilities have made it a viable candidate for the synthesis of nanocomposites. Organoclay nanocomposites such as polyacrylamide-bentonite, polyaniline-montmorillonite, and β-cyclodextrin-bentonite have been synthesized for the selective removal of various heavy metals such as Cu2+, Co2+, among others. Bacterial clay nanocomposites such as E. coli kaolinite nanocomposites have also been successfully synthesized and applied in the removal of heavy metals. Low-cost nanocomposites of clay using biopolymers like chitosan and cellulose are especially in demand due to the cumulative abundance of these materials in the environment. A comparative analysis of different synthetic processes to efficiently remove heavy metal contaminants with clay-based nanocomposite adsorbents is made.

Current synthesis and characterization techniques for clay-based polymer nano-composites and its biomedical applications: A review

Clays and its composites have received considerable attention recently due to their low cost, wide availability and low environmental impact. The development of various preparation processes and applications of innovative polymer–nanoclay composites has been aided by recent breakthroughs in material technologies. Novel polymer–nanoclay composites with better qualities have been effectively adopted in a variety of fields, including aerospace, car, construction, petroleum, biomedical, and wastewater treatment, owing to innovative production processes. Due to their superior qualities, such as increased density, strength, relatively large surface areas, high elastic modulus, flame retardancy, and thermomechanical/optoelectronic/magnetic capabilities, these composites are acknowledged as potential advanced materials. Hence the present paper reviews the advances in synthesis and preparation of clay-polymer nanocomposites. In addition, this study also focuses on the various techniques used for clay-polymer nanocomposites characterization e.g. scanning electron microscope (SEM), transmission electron microscope (TEM), thermo-gravimetric analysis (TGA) and differential colorimetric analysis (DSC), x-ray diffraction (XRD) analysis, Nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopic (FTIR) characterization. These advanced physico-mechanical and chemical characterization techniques would be effective in understanding the most appropriate application of clay polymer nanocomposites. In addition, the application of clay polymer nanocomposites in biomedical sector is also discussed in brief.

Chemical modification of clay nanocomposites for the improvement of the catalytic properties of Lipase A from Candida antarctica

Kaolin is a mineral composed of hydrated aluminum silicates, clayey and with high bioavailability. The choice of this mineral as immobilization matrix took into account these aspects mentioned above and its high surface area conducive to enzymatic immobilization, containing many OH- binding groups on its surface. Subsequently, the kaolin was functionalized with carboxymethylcellulose and polyethyleneimine (K-CMC-BPEI) and activated with Glutaraldehyde (K-CMC-BPEI-GLU) as a support to immobilize CAL-A. The K-CMC-BPEI-GLU@CAL-A was characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry (TGA), and Scanning Electron Microscopy (SEM). K-CMC-BPEI-GLU@CAL-A, in the temperature range of 50–80 ºC, has a half-life 2–3 times longer than soluble CAL-A, that is, the immobilization process conferred greater stability thermal to the biocatalyst. Furthermore, docking studies showed that the immobilization of CAL-A on the support surface was favorable, since CAL-A has binding affinity to the protein-anchored ligand, estimated at −4.3 to −3.7 kcal/mol. Experiments were performed to verify the catalytic potential of K-CMC-BPEI-GLU@CAL-A at a kinetic resolution of rac-1-(triisopropylsilyl) penta-1,4-diyn-3-ol (1) in an organic medium via an acylation reaction. All experiments yielded the product ((R)-1-Ac) with an excellent enantiomeric excess (ee >99%) and enantioselectivity (E > 200).

Synthesis and characterization of silver doped magnetic clay nanocomposite for environmental applications through effective RhB degradation

Synthesis and characterization of silver doped magnetic clay nanocomposite for environmental applications through effective RhB degradation

AFM Characterization of Halloysite Clay Nanocomposites' Superficial Properties: Current State-of-the-Art and Perspectives.

Natural halloysite clay nanotubes (HNTs) are versatile inorganic reinforcing materials for creating hybrid composites. Upon doping HNTs with polymers, coating, or loading them with bioactive molecules, the production of novel nanocomposites is possible, having specific features for several applications. To investigate HNTs composites nanostructures, AFM is a very powerful tool since it allows for performing nano-topographic and morpho-mechanical measurements in any environment (air or liquid) without treatment of samples, like electron microscopes require. In this review, we aimed to provide an overview of recent AFM investigations of HNTs and HNT nanocomposites for unveiling hidden characteristics inside them envisaging future perspectives for AFM as a smart device in nanomaterials characterization.

Experimental study on fabrication, biocompatibility and mechanical characterization of polyhydroxybutyrate-ball clay bionanocomposites for bone tissue engineering

The poly (3-hydroxybutyrate) (PHB)/ball clay nanocomposites (B1-B10) were synthesized using solvent casting method with different weight percentage of ball clay in PHB matrix. Scanning electron microscope (SEM) showed maximum root mean square roughness (188.73 μm) for 10% ball clay loading. Fourier transforms infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) showed establishment of intercalated structure and formation of hydrogen bond between ball clay and PHB matrix. Contact angle values (67.3 - 51.3°) exhibited that the nanocomposites (B1-B10) are more hydrophilic than neat PHB (70.30°). Thermogravimetric (TGA) and differential scanning calorimetry (DSC) revealed maximum Tmax (278 °C) and Tm (175 °C) for the nanocomposite B10 (PHB/PEG/ball clay: 80%/10%/10%). Maximum tensile strength (38.21 ± 0.15 MPa) and Young’s modulus (1.74 ± 0.016 GPa) was observed for B10 nanocomposite. The values of protein adsorption, platelet adhesion, PT, APTT and complement activation for B10 nanocomposites were 165 ± 2 μg/cm2, 72 ± 3 × 109 platelets/cm2, 23 ± 1 s, 44 ± 2 s, 102 ± 2 mg/dL and 631 ± 3 mg/dL, respectively. Hydroxyapatite formation was also observed for nanocomposite (B10) in in vitro simulated body fluid (SBF) study. Finally, the nanocomposite (B10) showed no harmful effect on MG-63 cells, indicating that they are physiologically safe.

Mechanical and Moisture Barrier Properties of Epoxy-Nanoclay and Hybrid Epoxy-Nanoclay Glass Fibre Composites: A Review.

Epoxy clay nanocomposites have been proven to have improved mechanical, thermal and physical properties over pristine matrix. Thus, the fields of application of epoxy–clay nanocomposites along with their hybrid glass/carbon fibre reinforced composites have grown tremendously during the last few decades. The present review paper covers the research work performed on epoxy clay nanocomposites. It includes the influence of the processing techniques and parameters on the morphology of the nanocomposite, the methods of characterization and the effects of adding nanoclay on the mechanical and physical properties of composite. The improvements in the liquid barrier properties brought about by the addition of nanoclay platelets to epoxy resin are discussed. The variation of physical and mechanical properties with nanoclay type and content are reviewed along with the effects of moisture uptake on these properties. The advances in the development, characterization and applications of hybrid glass fibre reinforced epoxy–clay nanocomposites are discussed. Findings of the research work on the influence of nanoclay addition and exposure to water laden atmospheres on the behaviour of the hybrid glass fibre epoxy–nanoclay composites are presented. Finally, the potential health and environmental issues related to nanomaterials and their hybrid composites are reviewed.

Moisture absorption and spectroscopic studies of epoxy clay nanocomposite

Epoxy resins are prone to serious moisture absorption inspite of their inherent advantages, which can be mitigated by the incorporation of montmorillonite nanoclay that provide tortuous path to flow of moisture. Moisture absorption studies of epoxy clay nanocomposites is carried out, to analyse the effect of nanoclay content, immersion media and immersion temperature. Nanocomposites prepared in 0.5, 1 and 1.5 wt% using magnetic stirring and ultrasonication and neat epoxy specimen were immersed in distilled water and artificial seawater maintained at 28 and 38 °C till saturation. Fick’s and Langmuir’s models were applied to calculate the kinetic parameters from the water absorption graphs. Atomic force microscopy (AFM), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope with energy dispersive X-ray (SEM–EDX) characterizations were performed. Diffusivity is least for nanocomposite containing 0.5 wt% nanoclay at both temperatures in both medium. However, it is least when the medium is distilled water. As the temperature of immersion medium increases, the diffusivity also increases. Saturation moisture uptake increased with increase in nanoclay content, because of the residual hydrophilic nature of nanoclay. AFM and XRD analysis revealed better dispersion and exfoliated structure of nanoclay respectively at 0.5 wt% loading. FTIR spectroscopy was applied to identify the chemical bonds that helped in proposing the reaction mechanism of the nanocomposite synthesis. Spectra comparison of dry and wet specimens complimented the moisture absorption data by showing lower infrared transmittance in wet specimens. With Increase in nanoclay content, the transmittance decreased corresponding to increase in saturation moisture uptake for distilled water immersed specimens. SEM–EDX analysis distinguished between the cations entered from the artificial seawater and cations that were still present in the nanoclay.