Nanoclay Content Research Articles

8-Hydroxyquinoline/nanoclay epoxy nanocomposite as a smart coating for early corrosion detection

ABSTRACT The effect of different concentrations of nanoclay incorporated in the epoxy coating containing 8-hydroxyquinoline (8-HQ) on early corrosion detection, electrochemical and optical properties of the applied coating was investigated. The 8-HQ and nanoclay composite samples were characterised by UV–Vis spectroscopy, FE-SEM, EDS, XRD, EIS, fluorescence spectroscopy and microscopy. Then, the optimised coating containing 8-HQ and nanoclay was applied on the Ti–Ni conversion coated steel for further analysis. Adhesion measurements indicated that the adhesion strength of the 8-HQ + Nano + TiNiCC was 4.6 ± 0.45 MPa with dominant cohesion failure. Based on the EIS measurement, the polarisation resistance of Ti–Ni modified steel coated with 0.1 wt-% 8-HQ and 2 wt-% nanoclay composite was about 1.5 × 1010 ohm.cm2 even after 4 weeks immersion in 3.5 wt-% NaCl solution. During the same period as a result of fluorescence microscopic study, the fluorescent spot appeared as a result of Fe2+/Fe3+ ions production at anodic regions.

Effect of Nanoclay Addition on the Morphology, Fiber Size Distribution and Pore Size of Electrospun Polyvinylpyrrolidone (PVP) Composite Fibers for Air Filter Applications

The fabrication of Polyvinylpyrrolidone (PVP) electrospun layers for air filter applications is the target of this study. Solutions of 10% PVP containing 0, 3, 10 and 25 wt% nanoclay were used to fabricate electrospun fibers. Scanning electron microscopy showed that the fibers’ roughness increased by increasing the nanoclay content, and it was maximum at the nanoclay concentration of 25 wt%. Concurrently, nanoclay decreased the pore size considerably and increased the range of the fibers’ size distribution up to 100%. In addition, as the nanoclay concentration increased, the frequency distribution decreased abruptly for the larger fiber sizes and increased dramatically for the small fiber sizes. This phenomenon was correlated to the effect of nanoclay concentration on the conductivity of the solution. The solution’s conductivity increased from 1.7 ± 0.05 µS/cm for the PVP solution without nanoclay to 62.7 ± 0.19 µS/cm for the solution containing 25 wt% nanoclay and destabilized the electrospun jet, increasing the range of fiber size distribution. Therefore, the PVP solution containing 25 wt% nanoclay has potential characteristics suitable for air-filter applications, owing to its rougher fibers and combination of fine and thicker fibers.

Physical and mechanical evaluation of dental resin composite after modification with two different types of Montmorillonite nanoclay

Evaluation of degree of conversion (DC), flexural properties, micro-hardness and color change (ΔE00) of dental resin composite after modification with two types of organo-modified Montmorillonite (MMT) nanoclay; an experimentally synthesized polymethyl-methacrylate modified MMT nanoclay (PMMA/MMT), and a commercially available one (Cloisite20A). MMT was synthesized by sol-gel technique, organo-modified with polymethyl-methacrylate and characterized using EDX, XRD and FTIR. PMMA/MMT and Cloisite20A nanoclay were added to flowable resin composite in 0.5, 1 and 1.5 wt% concentrations. Unmodified resin composite was used as control group. DC was assessed by FTIR, flexural properties were tested by three-point bending test using a universal testing machine, micro-hardness was analyzed by Vickers micro-hardness tester and color change (ΔE00) was evaluated using a reflective spectrophotometer. SEM and elemental mapping assessment were performed to evaluate nanoclay distribution in resin composite. Data were analyzed using One-way ANOVA followed by Tukey's post hoc test, in addition to Two-way ANOVA (p≤0.05). Weibull analysis was used to analyze flexural strength results. Characterization results revealed successful preparation of PMMA/MMT. DC results showed insignificant difference up to 1wt% of nanoclay concentration. Addition of 0.5wt% of PMMA/MMT significantly increased flexural properties, while addition of 1.5wt% of PMMA/MMT significantly decreased flexural properties. Micro-hardness results revealed a significant increase in PMMA/MMT groups in all tested concentrations. ΔE00 results showed that color change was clinically acceptable on adding 0.5wt% nanoclay. PMMA/MMT in 0.5wt% is a promising nanofiller for resin composite that significantly enhanced flexural strength and micro-hardness without compromising DC and color.

An experimental investigation on the low-velocity impact performance of the CFRP filled with nanoclay

In this study, the effect of the commercial nanoclay Cloisite® 20A on the impact response of the carbon fiber reinforced polymers was investigated using a low-velocity drop-weight impact machine under three impact energy levels of 10 J, 15 J, and 20 J. Contrary to other studies and for more improvement of the properties, clay nanoparticles were dispersed in the resin through solution blending methodology, and laminate samples were fabricated by vacuum infusion process. The optimal percentage of nanoclay was determined by tensile and flexural tests on the epoxy samples containing various nanoclay contents (0.2-0.8 wt.%). For a deeper understanding of the damaged nanocomposites, force-time, force-displacement, and energy-time responses were analyzed. Finally, the influence of nanoclay incorporation by solution blending method and the impact-induced damages were explored by measuring the permanent indentation, radiographic analysis, optical and field emission scanning electron microscopy. Addition of 0.2 wt.% Cloisite® 20A led to a significant increase in the maximum impact force (up to 25.7%), a reduction of the absorbed energy (up to −50.25%), and a decrease in the maximum displacement (up to −29.08%). Moreover, the permanent indentation and the delamination area were significantly decremented compared to the other studies using direct dispersion to disperse nanoclay in the resin matrix. Furthermore, it was revealed that the addition of nanoclay resulted in the transition of the failure mode of carbon fiber reinforced polymer during low-velocity impact from delamination to matrix cracking.

Physical and biological properties of electrospun poly(d,l-lactide)/nanoclay and poly(d,l-lactide)/nanosilica nanofibrous scaffold for bone tissue engineering.

Electrospun scaffolds exhibiting high physical performances with the ability to support cell attachment and proliferation are attracting more and more scientific interest for tissue engineering applications. The inclusion of inorganic nanoparticles such as nanosilica and nanoclay into electrospun biopolymeric matrices can meet these challenging requirements. The silica and clay incorporation into polymeric nanofibers has been reported to enhance and improve the mechanical properties as well as the osteogenic properties of the scaffolds. In this work, for the first time, the physical and biological properties of polylactic acid (PLA) electrospun mats filled with different concentrations of nanosilica and nanoclay were evaluated and compared. The inclusion of the particles was evaluated through morphological investigations and Fourier transform infrared spectroscopy. The morphology of nanofibers was differently affected by the amount and kind of fillers and it was correlated to the viscosity of the polymeric suspensions. The wettability of the scaffolds, evaluated through wet contact angle measurements, slightly increased for both the nanocomposites. The crystallinity of the systems was investigated by differential scanning calorimetry highlighting the nucleating action of both nanosilica and nanoclay on PLA. Scaffolds were mechanically characterized with tensile tests to evaluate the reinforcing action of the fillers. Finally, cell culture assays with pre‐osteoblastic cells were conducted on a selected composite scaffold in order to compare the cell proliferation and morphology with that of neat PLA scaffolds. Based on the results, we can convince that nanosilica and nanoclay can be both considered great potential fillers for electrospun systems engineered for bone tissue regeneration.

Investigating the preparation and characterization of nano-clay modified asphalts

In order to extend the lifespan of flexible pavements materials, a binder quality requests to be modified. The aim of the present research is to assess the physical features of original and modified asphalts with nanoclay materials. These features including; softening point values, penetration grades, viscosity values, penetration index values, and ductility. Three percentages of nanoclay contents (3, 5, and 7) % by of the asphalt weight were blended by a shear blender set at (4000) rpm., and mixing time set about 45 min. at 140 °C. Physical tests results showed that adding nanoclay material as a modifier was beneficial in enhancing the asphalts features. For example, viscosity values and softening point values increase when increase in the nanoclay content. Consequently, the mixing temperatures and compaction temperatures of the modified asphalts increase with increase the nanoclay content to reach (170 °C). While the penetration and ductility values decrease when increase the modifier content. Regarding the penetration index of the modified asphalts, it is enhanced by increase in the nanoclay proportions. Hence, the modified asphalt with 7% of nanoclay produces the greater value of penetration index accordingly, it has a positive influence on the rutting resistance.

Improving the Dyeability of Polypropylene Fibers Using Nanoclay and Plasma Treatment

In this study, polypropylene (PP) and polypropylene/nanoclay composite multifilament yarns with different nanoclay contents were prepared by melt spinning. The knitted fabrics were then made from these yarns and subjected to oxygen plasma treatment for 5 min. The samples were dyed with a disperse dye and an acid dye and the color strength, color coordinates, and fastness properties of the dyed samples were compared. The effect of plasma treatment on the surface chemistry and morphology of the samples was evaluated using Fourier-transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) analyses, respectively. FTIR analysis confirmed the introduction of oxygen-containing groups on the surface of the plasma-treated samples. AFM images confirmed etching of the fibers, and the surface roughness of the fibers increased significantly after plasma treatment. The incorporation of nanoclay in the multifilament yarns improved the dyeability of the polypropylene/nanoclay composite fibers with disperse and acid dyes. The optimum amount of the nanoclay for obtaining the highest color strength was 2 wt% and 1 wt%, for dyeing with the disperse and acid dye, respectively. Plasma treatment enhanced the dyeability and fastness properties of the fibers. The highest K/S values obtained on plasma-treated PP/nanoclay samples were 1.27 and 10.88 for acid and disperse dyes, respectively. The fastness properties of the samples dyed with the acid dye were generally lower than those of dyed with the disperse dye. The highest washing, dry rubbing, and light fastness properties were obtained on plasma-treated and disperse-dyed PP/nanoclay (2 %) sample, which were 4–5, 3, and 5, respectively.

Preparation and characterization of nanoclay loaded polyacrylonitrile hollow fiber membranes

New Polyacrylonitrile (PAN) nanoclay hollow fiber membranes were successfully fabricated through the dry-jet wet spinning process. The effects of adding the nanoclay on the hollow fiber mechanical properties and permeation performance and dye removal from water were investigated. Direct red 80, Direct orange 26 and Direct brown 2 dyes were used for dye removal experiments. Field emission scanning electron microscopy (FESEM) was used to analyze the cross-sectional and surface morphology and porosity. X-ray diffraction (XRD) has been used to compare crystalline structure of the fabricated hollow fiber membranes. The results showed that permeation is increased by adding nanoclay to the spinning dope. In addition, hollow fibers spun with lower nanoclay content showed lower hydraulic permeability and higher dye removal efficiency. Tensile strength increased from 1.09 to 2.06 with 3 wt% nanoclay loading.

Hybrid Layered Silicate/Calcium Carbonate Reinforced High-density Polyethylene Nanocomposites: Systematic Morphological Evaluation through Rheological Properties and Response Surface Method

High-density polyethylene (HDPE) based hybrid nanocomposites comprising varying concentrations of layered nanoclay (NC) and spherical nano calcium carbonate (nCaCO3) were prepared by a two-step melt compounding process in the presence of polyethylene grafted maleic anhydride (PE-g-MA) as the compatibilizer. Regarding multiple material variables (the NC, nCaCO3 and compatibilizer contents) participated in fabrication of the nanocomposites, response surface methodology (RSM) was utilized to find the correlation between the material variables, morphology and viscoelastic responses in the melt state. Intercalation of the layered silicates was investigated by X-ray diffraction (XRD) technique, and morphological characterization of the nanosized calcium carbonates was carried out by scanning electron microscope (SEM). The findings indicated that higher contents of the PE-g-MA facilitated the intercalation process and increased the interlayer distance. Interestingly, incorporation of the second nanoparticle, nano calcium carbonate, resulted in viscosity increment which is an influential factor on applied stresses during the melt mixing and subsequently, dispersion state of the nanoclay layers. The interplay between the designated material parameters was also discussed by means of interaction plots.

Electrical properties of polymer blend composites based on Silicone rubber/EPDM/clay for high voltage insulators

Silicone rubber (SR) and ethylene-propylene-diene monomer (EPDM) are widely-used polymers as housing for high voltage insulators. In this work, SR/EPDM/clay nanocomposites were obtained by two-roll mill mixing for outdoor polymeric insulators. Morphology, dielectric properties, dielectric breakdown strength (DBS), and surface and volume resistivity of different weight contents of nanoclay (Cloisite 15A) incorporated in SR, EPDM, and SR/EPDM hybrid nanocomposites were characterized. In addition, the distribution of breakdown voltages was fit to the distribution of Weibull and estimated the scale and shape parameters. The polar groups of the clay particles enhanced the polarization capability of the nanocomposites. Moreover, DBS results showed an enhancement of the dielectric strength proportional to clay content. Finally, the surface and volume resistance of all nanocomposites decreases but maintains very high electrical resistance. The experimental data presented in this study will be useful for designing and manufacturing the outdoor insulators.

Apparent and plastic viscosities prediction of water-based drilling fluid using response surface methodology

Apparent and plastic viscosities are two of the significant rheological properties of drilling fluid. Monitoring the apparent and plastic viscosities during drilling operations is essential to prevent various drilling problems and achieve successful drilling operations. Due to the constraints associated with experimental measurements, a reliable prediction is regarded as an excellent alternative for quick assessment of the apparent and plastic viscosities. There were many attempts taken to develop models to predict the apparent and plastic viscosities. However, the published models' main problems are their lack of accuracy and limitation of the parameters included. Therefore, this work presents new statistical-based empirical correlations for the prediction of apparent and plastic viscosities. The developed correlations relate the apparent viscosity and plastic viscosity to some variables, viz. bentonite, nanoclay concentration, nanosilica concentration, and temperature. Published data were utilized, and Response Surface Methodology (RSM) was used to obtain the mathematical relation between the variables and responses and describe the variables' interactions. ANOVA then validated the correlations, F-statistics test, fit statistics, and Pareto chart standardised effects. The validation has shown that the RSM models were more robust with high accuracy. The influence of the independent variables on the apparent and plastic viscosities of the drilling fluids was established in response surface plots (3D), and the interaction between variables in the system was found statistically significant. The results show that the RSM model's performance is accurate, reliable, and can, hence, be used for precise prediction of apparent and plastic viscosities.

Effect of silane concentration on the properties of crosslinked linear low density polyethylene‐montmorillonite nanocomposite

AbstractIn this study, linear low density polyethylene (LLDPE) was grafted and crosslinked by reactive extrusion melt compounding using different silane concentration with and without the presence of montmorillonite (MMT) nanoclay. The effects of different silane concentration and the addition of nanoclay filler on the degree of crosslinking, mechanical, thermal, rheological, and morphological properties were investigated and reported. Gel content results for all crosslinked samples were found to increase with increasing silane concentration. Tensile strength and Young's modulus of crosslinked LLDPE samples increased with increasing silane concentration compared to neat LLDPE; while the crosslinked LLDPE samples containing nanoclay have achieved higher tensile strength and Young's modulus, indicating strong interfacial interaction between silane grafted LLDPE matrix and nanoclay. However, the decrease of elongation at break for all crosslinked samples were observed compared to neat LLDPE. A reduction in the degree of crystallinity for crosslinked samples, particularly crosslinked samples containing nanoclay, was shown by thermal analysis results; whereas the melting temperature did not change significantly with increased silane concentration and subsequent addition of nanoclay. Thermogravimetric analysis results have revealed significant thermal stability improvement for neat LLDPE with increased silane concentration. Furthermore, crosslinked samples containing nanoclay have achieved better thermal stability compared to crosslinked samples without nanoclay. At lower frequency, it was found that viscosity, and storage modulus of neat LLDPE increased with increased silane concentration due to crosslinking and further addition of nanoclay into crosslinked LLDPE. The transmission electron microscopy results confirmed the intercalated structure of the nanocomposite for the crosslinked samples containing nanoclay.

Triaxial Mechanical Properties and Micromechanism of Calcareous Sand Modified by Nanoclay and Cement

Calcareous sand is developed by the fracture of marine biological skeleton under the impact of seawater. Calcareous sand is not transported in the process of deposition. Therefore, calcareous sand retains the characteristics of marine biological skeleton, low strength, and porous. In order to study the effect of nanoclay and cement on the modification of calcareous sand, a series of tests were carried out on the modified cement calcareous sand (CCS) with different content of nanoclay. In this study, the triaxial mechanical properties and failure modes of nanoclay and cement composite modified calcareous sand (NCCS) were studied through the triaxial UU test. Then, SEM tests were carried out on CCS and NCCS samples, and the micromechanism of nanoclay and cement composite modified Nanhai calcareous sand was analyzed. The results showed that (1) the shear properties of CCS could be improved by adding nanoclay. The optimum admixture ratio of nanoclay was 8%, and its peak stress was 23%-39% higher than that of CCS. (2) The peak stress and strain of NCCS showed a linear correlation. (3) Compared with CCS, the internal friction angle and cohesion of NCCS were increased by 5.2% and 52%, respectively. (4) Nanoclay could improve the compactness and structure of cement calcareous sand, and the macroscopic performance is the improvement of peak stress and cohesion.

Influence of the Nanoclay Concentration and Oil Viscosity on the Rheological and Tribological Properties of Nanoclay-Based Ecolubricants

This manuscript describes a rheological and tribological study carried out on eco-friendly lubricants. These ecolubricants were made up of nanoclays as dispersed phase (a layered nanosilicate (montmorillonite Cloisite 15A) and a fiber-like nanoclay (sepiolite Pangel B20)) and vegetable-based oil as continuous phase (castor oil (CO), high oleic sunflower oil (HOSO) and their mixtures). A series of nanoclay-based ecolubricants were prepared by varying both nanoclay concentration and base oil, and thus, its viscosity. Friction and wear behaviors were assessed by using a ball-on-three plates tribometer cell. The results showed that the fiber-like sepiolite Pangel B20 yielded an important reduction in the wear scar diameter, thus revealing its potential as anti-wear and load-carrying additive in ecolubricant formulations, while Cloisite 15A proved to have friction improving properties. These anti-wear and friction reducing properties were found to be influenced by both nanoclay concentration and oil viscosity.

Optimization of Topography and Surface Properties of Polyacrylonitrile-Based Electrospun Scaffolds via Nonoclay Concentrations and its Effect on Osteogenic Differentiation of Human Mesenchymal Stem Cells.

Nowadays, mesenchymal stem cells (MSCs) are the most widely used cell sources for bone regenerative medicine. Electrospun polyacrylonitrile (PAN)-based scaffolds play an important role in bone tissue engineering due to their good mechanical properties, which could be enhanced by the presence of nanoparticles such as nanoclay. This study evaluated the in-vitro effect of different concentrations of nanoclay in surface characteristic properties of PAN-based electrospun nanofiber scaffolds and the osteogenic differentiation ability of adipose-derived mesenchymal stem cells (AD-MSCs). After electrospinning nanofibers, their structure were assessed through some characterization tests. Then AD-MSCs isolation and characterization were done, and the cell attachment and the biocompatibility were determined. Finally, osteogenic differentiation-related markers, genes, and proteins were studied. Clay-PAN25% electrospun nanofiber scaffold could support attachment, proliferation, and osteogenic differentiation of AD-MSCs better than other groups. Also, nanoclay could enhance the properties of PAN-based scaffolds, such as fiber diameter, topography, surface charge, hydrophilicity, roughness, and degradation, as well as osteogenic differentiation of cells. As a result, Clay-PAN25% with the highest concentration of nanoclay was found as a promising biodegradable and cost-effective scaffold for osteogenic differentiation of AD-MSCs.

Consolidation Behavior and Compression Prediction Model of Coastal Cement Soil Modified by Nanoclay

Coastal cement soil modified by nanoclay (NCS) has particular research significance as a modification approach to improve the high compressibility of coastal cement soil (CCS). At curing ages of 7 days and 28 days, consolidation and SEM tests were performed on 6 groups of NCS samples with a nanoclay content between 0% and 10% and 6 groups of CCS samples with a cement content between 10 and 20%, and a compression prediction model was established based on the test results. Test results show that (1) there is a linear interval for the improvement effect of the increment of cement content on the compression of CCS samples. In this test, the cement content in this interval is between 12% and 18%. CCS with a cement content of 18% is preferred. (2) The improvement effect on the compression of the sample is better with a nanoclay content of 4% and 8%, but poor with a content of 2%. At a consolidation pressure between 100 kPa and 800 kPa, NCS with a nanoclay content of 4% is preferred. (3) Adhesion is better with a nanoclay content of 4%, and the filling effect is better with a content of 8%. (4) The cosine‐power function‐exponential model is established, and the measured data are fitted, and a prediction model for the compression amount of CCS and NCS is established.

Microstructural and Finite Element Analysis - Assisted Nanomechanical Characterization of Maize Starch Nanocomposite Films

Biocomposite films were prepared using normal maize starch plasticized with glycerol and water and sodium montmorillonite clay particles employing the solution mixing procedure. Scanning electron microscopy (SEM), X-ray diffraction (XRD), three-dimensional profilometry and tensile along with nanoindentation tests assisted with a Finite Element Analysis (FEA) were used for the assessment of starch-based films with various percentages of nanoclay particles. XRD analysis revealed intercalation of the test specimens while their morphology was ascertained using SEM/EDX. The FEA results were compared with the experimental measurements from nanoindentation and tensile tests. A satisfactory correlation was obtained between the experimental measurements and the computational models, demonstrating FEA-assisted nanoindentation as a useful technique for assessment, showing the effect of the different nanoclay concentrations on the mechanical properties.

A study on coating with nanoclay on the production of flame retardant cotton fabrics

In this study, flame retardant properties of 100% cotton fabrics were tried to be improved by using commercial nanoclay (Cloisite 20A) which is a clay based montmorillonite. Flame retardancy and thermal decomposition behavior of the samples were characterized by the vertical burning test, limiting oxygen index (LOI), and thermogravimetric analysis (TGA). The surface morphology of untreated and treated fabric was examined using a scanning electron microscope (SEM). Fourier-transform infrared spectroscopy (FTIR) analysis was carried out for Cloisite 20A, untreated and coated fabrics. The results of the tests showed that the coating treatment even at low nanoclay concentration is enough to have a considerable flame retardant effect. This result was attributed to the barrier effect of the nanoclay.

Improving moisture and fracture resistance of warm mix asphalt containing RAP and nanoclay additive

Using warm mix asphalt (WMA) and reclaimed asphalt pavement (RAP) has both significant environmental and financial benefits for countries; however, fracture resistance of RAP in subzero temperatures and moisture susceptibility of WMA has been a setback for utilizing these technologies broadly in the field. Since the fracture behavior of WMA and RAP has not been studied simultaneously, this study undertakes to assess the performance of WMA mixtures incorporating various content of RAP materials with the addition of nano clay as additive. In order to meet this objective, fracture toughness of semi-circular bend (SCB) specimens made by different RAP ratio (0, 20, 30 and 40%) and nano clay content (0 and 3%) was studied in two subzero temperatures (−10 and −20 °C) under pure mode I, pure mode II, and two distinct mixed-modes (I/II). Moreover, indirect tensile strength (ITS) and AASHTO T283 tests were conducted to assess the influence of RAP and nano clay on moisture damage of WMA. The results show that the use of both RAP and nano clay has beneficial impacts on WMA mixtures in terms of fracture and moisture resistance. Moreover, the fracture resistance of samples rose with decreasing temperatures, and WMA mixtures are more prone to crack at mode mixities. Overall, the simultaneous use of WMA, RAP, and nano clay seems as an environmentally-friendly mixture that promises a better efficiency compared to conventional WMA.

Potato starch-based films: Effects of glycerol and montmorillonite nanoclay concentration

The films can be obtained from renewable resources such as polysaccharides, proteins, and lipids. Potato starch is a polysaccharide found in abundance, low cost, biodegradable, edible, and can be obtained from agro-industrial waste. In the present study, biodegradable films were obtained from potato starch mixed with montmorillonite nanoclay (MMT) as crosslinking agent and glycerin as a plasticizer; and thus characterize properties such as: permeability to water vapor, solubility, thickness, functional groups by FTIR, analysis of the morphology by scanning electron microscopy (SEM), and mechanical properties. 9 mixtures combining different proportions of glycerol (1, 1.5 and 2 ml) with montmorillonite nanoclay (MMT) (0, 0.03 and 0.05 g) were prepared.