Clay Nanoparticles Research Articles

Polymethyl Methacrylate/Polypropylene Blends Loaded with Graphene and Clay: Morphology, Mechanical Properties and Thermal Stability

In the research described here immiscible polymer blends based on amorphous poly(methyl methacrylate) (PMMA) and semi-crystalline polypropylene (PP) were produced via a melt-mixing method. The effects of the addition of graphene and clay nanoparticles on the compatibility and properties of the blends were investigated. Scanning electron microscopy results showed that the neat blends at all compositions were severely phase separated and a droplet-in-matrix morphology was attained. Introduction of graphene and clay caused the compatibility of the blends to be highly enhanced and, thus, a finer and more uniform morphology was obtained for the nanocomposites. Based on the morphology results, it was found that graphene had more affinity toward the PP phase and clay was more compatible with PMMA. This hypothesis was further proved via mechanical analysis and thermogravimetric analysis (TGA) results. The toughness of the neat blends was increased upon increasing the PP content; however, it was reduced for all the nanocomposites relative to the blend of the same polymer composition. The thermal stability of the blend at a composition of 70/30 PMMA/PP was improved via addition of clay and graphene. The first stage of degradation (PMMA) was shifted to higher temperatures once clay was added to the system while the second stage of degradation (PP) was impeded upon addition of graphene.

Development of a multifunctional nanocomposite system for protection, consolidation and microbial growth prevention of porous stones: A case study for the conservation of tuff

In this work, innovative, sustainable, multifunctional surface treatments for tuff protection that combine water-repellency, consolidating function and long-lasting antimicrobial activity were developed and tested. In particular, different water-based formulations were prepared by adding to a commercial polysiloxane treatment a biocide against biodeterioration, or clay nanoparticles to strengthen the tuff or their combination where the biocide was partially loaded into the nanoclay to join protective, consolidant and long-lasting biocide activity. The last formulation showed the best overall performances, since the constituents synergically improve its water-repellency and aggregative effectiveness without changing the color. Moreover, all surface treatments showed promising antimicrobial activity.

Effect of Nano-Clay Particles and Heat Treating on Pure and Fretting Fatigue Properties of Piston Aluminum Alloy under Stress-Controlled Cyclic Bending Loading

Effect of Nano-Clay Particles and Heat Treating on Pure and Fretting Fatigue Properties of Piston Aluminum Alloy under Stress-Controlled Cyclic Bending Loading

Green Synthesis of Soy Protein Nanocomposites: Effects of Cross-Linking and Clay Nanoparticles on the Mechanical Performance.

A green synthesis scheme was adopted for preparation of soy-protein-based clay nanocomposites, in which soy protein isolates (SPIs) were utilized as the biodegradable resin and clay nanoparticles (CNPs) were used as the nanoreinforcing phase. Cross-linking of the SPIs was realized through an aqueous reaction scheme with oxidized sugars (e.g., glucose and sucrose as the typical constituents of soy flours) as the cross-linkers. Toughening effects of the cross-linkers, process parameters, and CNPs on the mechanical properties (e.g., tensile strength, stiffness, strain at break, and toughness) of the resulting SPI-based clay nanocomposites were examined by micromechanical tensile testing. The cross-linking and toughening mechanisms of the SPI-based nanocomposites were evaluated by Fourier transform infrared spectroscopy, sol–gel and color characterization, scanning differential calorimetry, and transmission electron microscopy. Thermal stability of the cross-linked SPIs was evaluated by thermogravimetric analysis. Experimental results show that cross-linking can noticeably improve both the tensile strength and tensile modulus of the resulting SPI films, and a small quantity of CNPs can obviously alter the mechanical properties of the resulting clay nanocomposite films. The present study indicates that defatted soy flours can be directly utilized for developing low-cost, SPI-based nanocomposites without the need for external plasticizers, and the entire synthesis is completely green without involvement of any petroleum-based organic solvents, polymers, and metallic catalysts. Such biodegradable SPI-based green nanocomposites have the potential to substitute fossil-based plastics and polymer composites for use in various industrial products and house utilities.

Increased shelf life of Oncorhynchus mykiss (Rainbow trout) through Cu-Clay nanocomposites.

The online version contains supplementary material available at 10.1007/s10068-022-01031-0.

Nonlinear static and dynamic performance of CNT reinforced and nanoclay modified laminated nanocomposite plate

Under static and dynamic loading circumstances, the mechanically and thermo-initiated nonlinear static and dynamic assessment of the bending response of single-walled carbon nanotubes’ (CNTs’) fibers with a nanoclay particle reinforced polymer hybrid laminated composite plate is investigated. To evaluate the effective elastic characteristics of the CNTs’ fibers on the nanoclay particle modified polymer hybrid laminated plate, a modified Halpin–Tsai method is applied in an orthotropic way. The theory of higher-order shear deformation and complete kinematics (nonlinear) are used to develop the fundamental nonlinear dynamic formulation. A user-interactive finite element method-based MATLAB program solves the governing equations for nonlinear dynamic systems utilizing Newmark’s period integration and the Newton–Raphson method. The effects of variation in the quantity of CNTs’ fibers and particles of nanoclay, presence of interphases around CNTs’ fibers and nanoclay particles, variation in phases of the CNTs’ fibers on the nanoclay particle modified polymer hybrid laminated plate, and variation in plies of the laminated hybrid plate under clamped and simply supported conditions on the transverse central deflection response are explored in depth.

Improvement of the corrosion performance of AA2024 alloy by a duplex PEO/clay modified sol-gel nanocomposite coating

Due to the intrinsic porosity of the layers formed by the plasma electrolytic oxidation (PEO) process, the application of silane-based coatings as an eco-friendly layer is a promising way to diminish penetration of the corrosive species into the PEO coating by pores sealing. In this study, to enhance the corrosion protection of AA2024, the performance of the duplex system achieved by adding different concentrations in sodium montmorillonite (Na-MMT) dispersed into the silane coating was assessed. In this study, a hybrid sol-gel layer (30% V/V) obtained from tetraethoxysilane (TEOS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) sol-gel solution was applied on AA2024 previously covered by an optimized PEO layer using a solution containing sodium silicate and potassium hydroxide solution as electrolyte. Electrochemical impedance spectroscopy (EIS) revealed the significant impact of the sol-gel/clay nanocomposite layer on the corrosion protection performance of the PEO layer on the AA2024 substrate in a 0.1 M NaCl solution. Regarding, the low-frequency impedance of different coating systems upon five weeks exposure to the aggressive solution reported the sealing ability of the sol-gel coatings in which the silane coating modified with 1000 ppm of clay nanoparticles had the maximum corrosion resistance among them (i.e., higher than 107 after 5 weeks immersion). The flake-like structure of sodium montmorillonite not only enhanced the barrier performance, but also FT-IR outcomes reflected the reticulation of the silane network through the interaction of nanoparticles with SiOH groups of the silane layer.

Adsorptive behaviour of rutile phased titania nanoparticles supported on acid-modified kaolinite clay for the removal of selected heavy metal ions from mining wastewater

This study investigated the removal of metal ions pollutants in mining wastewater such as Mn (II), Fe (III), Pb (II) and Cu (II) ions by acid-activated kaolinite clay (AAC) and titanium (IV) oxide (TiO2) nanoparticles supported on the AAC (TiO2–AAC). TiO2 nanoparticles were synthesised using titanium salt precursor with leaves extract of Parkia biglobossa and impregnated on the AAC to develop TiO2-AAC as a nanoadsorbent. The AAC and TiO2–AAC nanocomposites were characterized using different analytical techniques. Actual concentrations of selected heavy metals in mining wastewater was determined prior and after treatment using the prepared adsorbents in batch adsorptive studies with atomic absorption spectrophometer. The characterisation studies confirmed that a rutile phase TiO2 was doped the on acid-activated kaolinite clay. Morphology analysis shows that the developed adsorbents were homogeneously dispersed and porous. The results of the surface area further revealed that the AAC, TiO2 and TiO2–AAC has 14.15, 10.23 and 32.98 m2/g, respectively. The percentage removal of heavy metals followed the order of TiO2–AAC > AAC due to the higher surface area and enhanced surface functionality of the former than the latter. The adsorption capacity increased from 86.13 to 91.99% (Fe (III)), 83.12 to 89.37% (Mn (II)), 68.48 to 81.95% (Cu (II)) and 29.49 to 32.39% (Pb (II)) from AAC to TiO2–AAC. The kinetic and isotherm models were best fitted by pseudo-second-order kinetics and Langmuir model. Whilst the thermodynamic investigation found that, the adsorption process was endothermic, spontaneous and chemisorption controlled. Conclusively, the TiO2–AAC nanocomposite exhibited better performance than AAC alone.

Mechanical properties of reinforced polymer concrete with three types of resin systems

The mechanical properties of polymer concrete (PC) with three types of resin systems were investigated. First, the effect of 0.5 wt% to 3 wt% basalt fibre on the mechanical properties of a quaternary epoxy-based PC was investigated experimentally and the best weight percentage of basalt fibre was obtained. The results showed that adding basalt fibre to the PC caused an enhancement of 10% in compressive strength, 10% in flexural strength, 35% in the splitting tensile strength and 315% in impact strength. In the next step, the effect of nanoclay particles on the mechanical properties of basalt-fibre-reinforced PC was analysed experimentally. Nanoclays increased the compressive strength up to 7%, flexural strength up to 27% and impact strength up to 260% but decreased the tensile strength of the PC. Field-emission scanning electron microscopy was performed to study the fracture surface and morphology of various concrete specimens. In the last step, the effect of two different resin systems (rigid polyurethane and rigid polyurethane foam) on the mechanical properties of the reinforced PC was investigated. The epoxy PC was found to have a higher specific strength than the polyurethane and ultra-lightweight polyurethane foam PC.

Effects of combined alkali treatment and clay nanoparticle infusion on thermo-mechanical response of kenaf/PLA biocomposites

Fibre-reinforced biocomposites have inherently low thermo-mechanical properties and hence require some treatments or modifications during the fabrication process in order to enhance these properties. In this work, a combination of alkalization and nanoparticle infusion was used in enhancing thermo-mechanical properties of kenaf fibre-reinforced polylactic acid biocomposites. The biocomposites were made using sodium hydroxide (NaOH) treated kenaf nonwoven mats and polylactic acid infused with clay nanoparticles. Fabrication of the biocomposites was done using the prepreg method and curing at high temperature. Investigation of the thermo-mechanical properties were performed using a thermogravimetric analyser (TGA) and dynamic mechanical analyser (DMA). Results showed that a combination of alkalization and nanoparticle infusion improves the thermal stability of the biocomposites, loss modulus and damping. However, alkalization and nanoparticle infusion decreased the glass transition temperature of the biocomposites. The study shows that combined treatment of biocomposites with sodium hydroxide and clay nanoparticles significantly improves their performance properties. Therefore, this expands the application capabilities of natural fibre reinforced biocomposites. Best results were obtained by a combination of NaOH treatment and infusion with 5 wt% clay nanoparticles.

NEW RESULTS OF FRACTAL FRACTIONAL MODEL OF DRILLING NANOLIQUIDS WITH CLAY NANOPARTICLES

In recent years, a new idea of the fractal fractional derivative has been introduced. However, it is not used for the free convection flow drilling nanoliquid with clay nanoparticles. In this paper, we have deliberated this new approach of the fractal fractional derivative with a power-law kernel for heat transfer in a drilling nanofluid with clay nanoparticle in a vertical channel. Water is taken as the base fluid. The flow of the fluid is between two fixed vertical parallel plates such that one of them is constantly heated. The resulting problem is modeled with a fractal fractional derivative operator with a power-law kernel. As the exact solution to this problem is not possible, therefore, the Crank–Nicolson Finite Difference Scheme (CNFDS) is used for numerical solutions. This idea for the fractal fractional fluid problem is used here for the first time in the literature. Results are portrayed in the various graphs using Maple-15 software. The importance of both fractal and fractional parameters is discussed in detail. Results showed that the fractal fractional parameter gives a more general solution of the velocity and temperature for the fixed fractional operators. Therefore, a mutual approach of fractal fractional clarifies the memory of the function better than fractional only.

Improving mechanical behaviour of collapsible soils by grouting clay nanoparticles

The primary geotechnical concern of collapsible soils such as loess is their hydromechanical instability. Upon wetting, metastable aggregates disintegrate, leading soil to collapse under the applied load or self-weight. In situ chemical stabilisation, such as grouting, is a favoured option to improve soil mechanical behaviour; however, the low permeability of loess limits the application of permeation grouting in such deposits. Here a new approach is presented based on the injection of dilute suspensions of montmorillonite clay nanoparticles to improve mechanical behaviour of low permeable loess. In addition to clay, the grouting behaviour of an ordinary cement material was evaluated as a typically favoured soil stabiliser. Reconstituted specimens were also prepared by mixing dry clay or cement particles with soil at similar contents and curing time to compare with the grouting method. SEM images were also taken from the cured samples to visualize the soil fabric. Results revealed that clay suspensions feature a high-mobility in the soil medium as well as a remarkable performance in reducing the collapse potential due to: (1) clay effective particle size (∼0.25μm) that facilitates its mobility in soil, and (2) formation of evaporation-driven solid bridges that reinforce the interparticle bonds during post grouting drying. Results encourage the application of clay nanoparticles over cement for an economical and eco-friendly grouting approach to improve the mechanical behaviour of low permeable collapsible soils.

Angiogenesis Promotion by Combined Administration of DFO and Vein Endothelial Cells Using Injectable, Biodegradable, Nanocomposite Hydrogel Scaffolds.

Desferrioxamine (DFO) upregulates HIF-1α and stimulates expression of vascular endothelial growth factor (VEGF), thereby accelerating neovascularization. As DFO acts primarily upon surrounding vein endothelial cells to stimulate angiogenesis, the angiogenic efficacy of DFO could be reduced in severely injured tissues lacking a sufficient number of vein endothelial cells. We hypothesized that combined administration of DFO and vein endothelial cells is a promising tissue engineering approach for promoting neovascularization. In this study, we evaluated the applicability of this approach using injectable, biocompatible, biodegradable nanocomposite gels consisting of poly(dl-lactide-co-glycolide)-b-polyethylene glycol-b-poly(dl-lactide-co-glycolide) (PLGA-PEG-PLGA) copolymers and clay nanoparticle LAPONITE. The nanocomposites exhibited irreversible thermo-gelation in the presence of DFO, and the mechanical strength was strongly affected by the amount of DFO. The storage moduli of the gels increased with increasing amount of DFO. These results indicate that the interaction between DFO and LAPONITE works as physical cross-linking points and facilitates the formation of the gel network. The nanocomposite gels achieved sustained slow release of DFO due to interactions between DFO and LAPONITE. Human umbilical vein endothelial cells (HUVECs) cultured on DFO-loaded nanocomposite gels exhibited a higher degree of vascular tube formation than cells cultured on nanocomposite gels without DFO. Moreover, the number of branching points and the diameter of the blood vessels regenerated in the gels significantly increased with increasing DFO amount, indicating that DFO released from the gels facilitates vascular tube-forming capacity. As a proof of concept, we demonstrate that the combined administration of DFO and vein endothelial cells using nanocomposite gels promotes greater angiogenesis than DFO administration alone using the same gels by in vivo experiments, confirming the validity of our hypothesis. Considering the multiple advantages of nanocomposite gels with regard to potential vascularization capacity, certain biocompatibility, biodegradability, and injectable cell- and drug-delivery capacity, we concluded that the nanocomposite gels have potential utility as scaffolding biomaterials for vascularization in tissue engineering applications.

Layered Biomimetic Composites from MXenes with Sequential Bridging.

Layer-by-layer (LbL) assembly is a widely used technique for the self-assembly of layered nanocomposites from clay sheets, carbon nanotubes, graphene oxide, nanoparticles, and other materials. Other approaches for fabricating layered nanocomposites include vacuum-assisted filtration and blade coating. They are simpler than LbL assembly, but they all introduce voids into the layered structure, thereby reducing the performance of the resulting nanocomposites. A team from Beihang University evaluated the void structure in Ti3 C2 Tx MXene composites and found that the fundamental problem with voids can be solved by the sequential nanoscale bonding of MXEne platelets with sodium carboxymethyl cellulose combined with covalent bridging with borate ions, thereby opening a new path to self-assemble two-dimensional platelets into continuous high-performance layered nanocomposites.

Layered Biomimetic Composites from MXenes with Sequential Bridging

AbstractLayer‐by‐layer (LbL) assembly is a widely used technique for the self‐assembly of layered nanocomposites from clay sheets, carbon nanotubes, graphene oxide, nanoparticles, and other materials. Other approaches for fabricating layered nanocomposites include vacuum‐assisted filtration and blade coating. They are simpler than LbL assembly, but they all introduce voids into the layered structure, thereby reducing the performance of the resulting nanocomposites. A team from Beihang University evaluated the void structure in Ti3C2Tx MXene composites and found that the fundamental problem with voids can be solved by the sequential nanoscale bonding of MXEne platelets with sodium carboxymethyl cellulose combined with covalent bridging with borate ions, thereby opening a new path to self‐assemble two‐dimensional platelets into continuous high‐performance layered nanocomposites.

Ethylene scavenging film based on corn starch-gum acacia impregnated with sepiolite clay and its effect on quality of fresh broccoli florets

Ethylene scavenging film based on corn starch (CS) and gum acacia (GA) nanocomposite film impregnated with sepiolite (SP) was fabricated by the casting method and characterized. FTIR, TGA, XRD, SEM, mechanical, water vapor barrier, and ethylene scavenging properties of CS/GA films with and without SP were carried out. The addition of SP in the CS/GA films showed improved elongation and lowered water vapor permeability in comparison to the control film. Interfacial interaction between the CS/GA and SP was observed in FTIR. The SEM images showed that SP clay nanoparticles were evenly distributed in the CS/GA film matrix. Increasing the SP into CS/GA films improves tensile strength, water vapor permeability, crystallinity, and thermal stability. The CS/GA/SP film showed ethylene scavenging properties increasing with SP. Based on mechanical, water barrier permeability, and ethylene scavenging properties, CS/GA film impregnated with 20% SP was optimal and was selected for broccoli florets packaging. Broccoli packaged in a CS/GA/SP20 film and stored at 23 °C for 6 d showed a reduction in loss of weight, color, and total soluble solids of broccoli florets. CS/GA/SP nano biocomposites films show great potential in the area of active packaging due to their good mechanical, barrier, and ethylene scavenging properties.

Experimental study of the effect of clay nanoparticles on the strength of hybrid sandwich panels under quasi-static loading

The aim of this study is to investigate the effect of clay nanoparticles on the strength of a hybrid sandwich structure with polyurethane foam core with two different densities. The sandwich structure is made of E-glass woven fabric and basalt fiber. Different percentages of clay nanoparticles are 0.0%, 0.1%, 0.3% and 0.5%, respectively. Furthermore, polyurethane foam with two densities of 40 and 140 (kg/m3) was used for the core of the sandwich structure. By force-displacement diagram obtained from quasi-static impact, the experimental studies of the effect of clay nanoparticles and polyurethane foam with different densities in this type of structure were performed. In addition, crashworthiness features including crush force efficiency and energy absorption capability were discussed. Finally, images of the damage surface and the cut view were taken and the results were reported in order to scrutinize the damage in the hybrid structure. The results indicate that with the increase of clay nanoparticles in the resin of the hybrid structure, the performance of the structure against the indenter effect is improved and displays good resistance. Furthermore, the strength of the structure is enhanced by increasing the density of polyurethane foam. Holistically, polyurethane foam prevents the spread of damage in all structures. In samples with foam with a density of 40 (kg/m3), the hybrid structure with 0.0% Nano absorbs more energy and in samples with foam with a density of 140 (kg/m3), has less energy absorption.

Investigating the mechanical performance of nano additives reinforced high-performance concrete

It is known that nanomaterials have been broadly employed worldwide as reinforcements for the production of high-strength and high mechanical performance concrete-based structures.Hereinafter, high-performance concrete (HPC) modified with three types of additives were synthesized: exfoliated nano clay (NC), nano-silica (NS), and hybrid particles [silica fume (SF) & limestone (LS)]. The compressive, splitting tensile and flexural strengths, were investigated at 28 days of hydration.The exfoliated NC was simply prepared via exfoliating the thermally activated ordinary clay with the aid of organic ammonium chloride. The results revealed that all types of the employed additives provided an augmentation in the mechanical properties of the hardened concrete mixes especially the mixes with a cement content of 350 kg/m3. Furthermore, the addition of 6% NC has improved the compressive strength of concrete with 350 kg/m3 by 17.06%, the splitting tensile strength by 7.32%, and the flexural strength by 13.21%. Furthermore, the compressive, splitting tensile and flexural strengths of the same concrete were enhanced by 9.57%, 12.1%, and 32.87% respectively, by adding 3% NS. Finally, incorporating (7.5% SF + 2.5% LS) led to an increase in the compressive, splitting tensile and flexural strengths of concrete by 10%, 2.64%, and 51.14%, correspondingly.

Induced orientation of magnetic bentonite nanoparticles to produce low-density polyethylene nanocomposites

Clay-polymer nanocomposites have considerable importance in various areas of engineering; however, the addition of hydrophilic clays into hydrophobic polymer matrices is a challenge due to the low affinity between them, causing performance problems. Thus, the aim of this work was developing a method to improve dispersion and generate a high aligned morphology in clay-polymer nanocomposites. For this, clay nanoparticles with magnetic properties were produced and incorporated (3 wt% and 5 wt%) in low-density polyethylene matrices. The effect of the alignment on the thermal and thermo-mechanical properties of polymer was evaluated. The use of an external magnetic field during the molding process led to an efficient alignment of the nanoparticles, where the magnetic clay nanoparticles lined up along the magnetic field lines. The presence of nanoparticles had a crucial impact on the thermal properties of the nanocomposites with increments up to 40 °C in the initial degradation temperature of the polymeric matrix by forming physical barriers distributed across the samples. The alignment of nanoparticles also resulted in increments of up to 43% in the storage modulus of the polymer as a result of improved adsorption of mechanical energy. The results indicated a very promising methodology with potential application in the production of new polymeric materials with high barrier properties to liquids and gases and thin films with magnetic shielding properties.

Compatibilization of PLA grafted maleic anhydrate through blending of thermoplastic starch (TPS) and nanoclay nanocomposites for the reduction of gas permeability

ABSTRACT Here, the effects of compatibilization and clay nanoparticles on the gas permeability of nanocomposites of poly-lactic acid (PLA)/thermoplastic starch (TPS)/nanoclay were discussed. TPS and compatibilized PLA/TPS were tailored in the first step. The starch with D-sorbitol as a plasticizer was mingled through the internal mixer. Afterward, the maleination method was utilized on PLA to ameliorate the compatibilization of PLA and TPS. In this regard, maleic anhydrate (MA) has been grafted on PLA in the presence of L101 as a peroxide initiator via melt mixing to obtain PLA-g-MA. The optimum content of PLA-g-MA was about 4 phr, confirmed by DMTA and SEM. Noteworthy, the presence of PLA-g-MA has moderately improved the oxygen barrier. Then, the nanocomposites of PLA and TPS containing 1% of Cloisite-30B as well as the optimum compatibilizer (4phr), were produced by melt mixing in the masterbatch module leading to the formation of an extraordinary well-dispersed structure according to XRD patterns. The mixing order controlled the localization of nanosheets. It was concluded that the inclusion of 1% nanoclay in the PLA phase reduces the oxygen permeability by 55% compared to the pristine blend due to the tortuosity effect of nanosheets that are appropriately dispersed in the matrix.