Nano Clay Research Articles

Improvement of the corrosion resistance of acrylic electrocoating in the presence of acid-modified montmorillonite nano clay

This study presents a novel approach to enhance the corrosion resistance of acrylic electrocoating by incorporating acid-modified montmorillonite nano clay particles at varying concentrations (0.0–0.5 wt%) into the coating matrix. The nanostructure and laminar shape of the nano clay particles were confirmed by field emission scanning electron microscopy (FE-SEM). XRD and FE-SEM/EDS analyses revealed successful modification of the nano clay and its uniform dispersion in the electrocoating film. The effect of the nano clay on the rheology of the coating was also investigated using rheometric methods. The anti-corrosion properties of the nanocomposite coatings were evaluated using salt spray and electrochemical impedance spectroscopy (EIS). The EIS results showed that the nanocomposite electrocoating containing 0.3 wt% of acid-modified montmorillonite nano clay exhibited remarkable improvement in anti-corrosion properties and corrosion resistance, with an impedance value of up to 10 Gohm after 21 days of immersion in NaCl 3.5 wt%.

Self-healing interpenetrating network hydrogel based on GelMA/alginate/nano-clay

Today, tissue engineering strategies need the improvement of advanced hydrogels with biological and mechanical properties similar to natural cartilage for joint regeneration. In this study, an interpenetrating network (IPN) hydrogel composed of gelatin methacrylate (GelMA)/alginate (Algin)/nano-clay (NC) with self-healing ability was developed with particular consideration to balancing of the mechanical properties and biocompatibility of bioink material. Subsequently, the properties of the synthesized nanocomposite IPN, including the chemical structure, rheological behavior, physical properties (i.e. porosity and swelling), mechanical properties, biocompatibility, and self-healing performance were evaluated to investigate the potential application of the developed hydrogel for cartilage tissue engineering (CTE). The synthesized hydrogels showed highly porous structures with dissimilar pore sizes. The results revealed that the NC incorporation improved the properties of GelMA/Algin IPN, such as porosity, and mechanical strength (reached 170 ± 3.5 kPa), while the NC incorporation decreased the degradation (63.8 %) along with retaining biocompatibility. Therefore, the developed hydrogel showed a promising potential for the treatment of tissue defects in cartilage.

The technological properties of particleboards manufactured with nano additive melamine-formaldehyde adhesive

In the present study, the effect of nano additives in different ratios added to melamine formaldehyde adhesives on the properties of particleboards was investigated. In this respect, two different nanoclays [organo-modified nanoclays (OMC) and unmodified nanoclays (NC)] and graphene nanoplatelet (GNP) were added to the adhesive at the rate of 1%, 2% and 4%. Along with the physical (thickness swelling and water absorption), mechanical properties (modulus of rupture, modulus of elasticity and internal bond strength), accelerated weathering and fire resistance tests (Limiting oxygen index-LOI) of the board were carried out. According to the results, while there was no significant change in the water absorption values with the use of nano additives, a decrease occurred in the thickness swelling values with the use of GNP. The mechanical properties increased with the use of nano additives. The highest values were obtained from the board groups using 1% GNP. The loss of mechanical resistance values after the accelerated weathering test was reduced with the use of 1% nanoclay and up to 2% GNP. According to LOI test results, the use of 1% and 2% nano additives increased the fire resistance of the boards., The agglomerations were determined in places with the increase in the nano additive ratio in the SEM images.

Cover Image, Volume 140, Issue 24

This image by Nithinart C. Juntadech illustrates cellulose acetate (CA)/nanoclay (NC)-based hollow fiber composite membranes with higher strength, porosity, and permeance prepared using wet spinning process. They were plausibly used for the separation of gaseous products during industrial scale dehydration of ethanol. DOI: 10.1002/app.54032

Properties and microstructures of 3D printable sulphoaluminate cement concrete containing industrial by-products and nano clay

Owing to its sound/thermal insulation and the elimination of the conventional moulds, 3D printable foam concrete (FC) has gained increasingly attention among researchers. In this study, the producibility of calcium sulphoaluminate cement-based foam concrete (CSA-FC) through concrete extrusion was confirmed, which also contains nano-clay (NC) and industrial by-products. The fresh and hardened properties, microstructures as well as extrudability of prepared samples were investigated. The initial results highlight the benefits of using appropriate amount of NC and desulfurized gypsum (FGD gypsum) for the hydration acceleration and extrudability improvement of samples. Meanwhile, the use of NC could alleviate the performance degradation owing to the use of industrial wastes in samples due to its nucleation and pozzolanic effects. Further, through the extrusion technology, a suitable mix design of CSA-FC with satisfactory performance, low carbon footprint and cost was proposed, which eliminates the conventional moulds during its production.

Fabrication of mixed matrix nanofibers with electrospraying and electrospinning techniques and their application to gas toluene removal

This study describes the fabrication and characterization of mixed matrix nanofiber air filters having adsorptive and photocatalytic properties. Two fabrication techniques were applied as (i) single electrospinning (SE) and (ii) successive electrospinning and electrospraying (SEE) for doping of photocatalyst (TiO2) in nanofiber structure. Polyacrylonitrile (PAN) was used as main polymer, the nanoclay (NC) was used with ratios of 0.5%, 1.0% and 2.0% (w/w) as nanoadsorbent and TiO2 was used as photocatalytic oxidation agent. TiO2 was integrated to the nanofiber structure with two doping methods (blended in solution and sprayed) providing as same TiO2 mass (0.2 g TiO2/g PAN) in unit area of final nanofiber structure. The water vapor transmission rate (WVTR) values showed a decreasing trend with the addition of NC and varies between 80 and 150 g/m2h. The presence of NC played a critical role in increasing of toluene adsorption capacity of nanofiber from 15% to 40% with increasing of NC amount. The maximum toluene degradation rates of mixed matrix nanofiber were found as 0.09 ppm/min for the NC2.0-TiO2-S coded nanofiber and 0.05 ppm/min for the NC2.0-TiO2 coded nanofiber. The integration of TiO2 to nanofibers with SEE was found as more effective for toluene oxidation than SE. With the electrosprayed TiO2, the contact area of nanofiber is further increased and the UVA light more easily activates TiO2 onto nanofiber. Among all nanofibers, NC2.0-TiO2-S coded nanofiber (doped TiO2 with SEE) is promising for air filter considering its filtration properties in general, as it has high toluene adsorption and oxidation efficiency, good air permeability, 93% particulate matter filtration efficiency and low pressure drop.

Cellulose acetate/nanoclay composite membranes with enhanced mechanical properties and improved permeance in gas separation

AbstractDiethyl ether is a valuable chemical product in petrochemical industry used in different applications. In diethyl ether (DEE) production by the dehydration of ethanol (EtOH), the products from DEE production are commonly mixed with EtOH and the % yield of DEE generally has not exceeded 60%. This contribution describes the preparation and performance of hollow fiber membranes for the separation of gaseous product (DEE) and reactant (EtOH). Cellulose acetate (CA)/nanoclay (NC)‐based hollow fiber composite membranes were prepared using a wet spinning process of CA solution and the addition of hydrophilic NC particles to improve the mechanical properties and permeability. According to the findings, the 20 wt% CA/0.5 wt% NC hollow fiber showed the higher mechanical strength than the 20 wt% CA hollow fiber without NC. Moreover, the 20 wt% CA hollow fiber without NC provided EtOH and DEE permeances of 8.44 × 10−11 and 4.25 × 10−10 mol m−2 s−1 Pa−1, respectively, while the 20 wt% CA/0.5 wt% NC hollow fiber showed higher EtOH and DEE permeances of 6.50 × 10−10 and 8.49 × 10−9 mol m−2 s−1 Pa−1 plausibly because of the higher porosity based on the SEM images. Furthermore, both CA hollow fiber membranes were selective for DEE over EtOH and were more selective with the addition of NC.

ANNbased prediction of the absorption characteristics of additive manufactured glycol‐modified polyethylene terephthalate nanocomposites reinforced with short‐carbon fibers and nanoclay fillers

AbstractIn this research work, an artificial neural network (ANN) based data driven prediction technique is proposed to evaluate the absorption characteristics of glycol‐modified polyethylene terephthalate (PETG) polymer nanocomposites reinforced with short carbon fibers (SCFs) and organically modified montmorillonite (OMMT) nanoclay (NC) fillers. The specimens are fabricated through additive manufacturing routine. The data points owing to the absorption of PETG nanocomposites are collected with the aid of the experimentation, which are then used to train the ANN model using Levenberg–Marquardt backward propagation algorithm. Different variants of PETG nanocomposites are prepared using various weight percentages of NC (1%, 3%, and 5%) and SCFs (5%, 10%, and 15%). The required filaments were prepared with the aid of compounding and extrusion processes. The specimens were printed using the fused deposition modeling technique. Further, the absorption behavior of these nanocomposites when exposed to distilled water, salt solution, and sugar solution has been experimentally studied following the ASTM D570 standard. The individual and combined effects of reinforcing OMMT‐NC and SCFs in the PETG matrix are also studied. The experimental results suggest that the absorption characteristics of PETG nanocomposites are significantly affected by the NC and SCFs reinforcements. The outcomes of this work will aid the design/material engineers in making a good trade‐off between the mechanical and absorption properties of the proposed PETG nanocomposites.

Electrospinning of cellulose acetate/graphene/nanoclay nanocomposite for textile wastewater filtration

In this study, electrospinning technique was used to prepare cellulose acetate (CA) and graphene oxide (GO) nanofiber composites along with nanoclay (NC) for filtration applications. For this purpose, different contents of GO and NC were added to the CA solution, and the electrospinning process was optimized to produce the finest fiber. The morphology and crystalline structures of the resulting nanofiber composites were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. According to the obtained results, the CA (12%)/GO (1%)/NC (1%) nanofiber had the minimum mean fiber diameter and uniform diameter distribution among all electrospun fibers. TEM images showed good dispersion of the employed nanostructures (GO and NC) in the fibrous membranes. The results of the mechanical test revealed 24% improvement in the tensile strength of the nanocomposite fiber (CA/GO/NC) in comparison with CA fiber. Thermogravimetric analysis (TGA) indicated that the presence of GO and NC led to higher thermal stability than pristine polymeric fiber. XRD results confirmed the presence of both amorphous and crystalline CA in the optimized sample. The spectrophotometric analysis showed that the amount of dye absorption increased after adding GO and NC to CA. In conclusion, the produced fibrous nanocomposite can be used as a potential filter for color removal in the textile industry.

Nanopowders as an additive for strength and durability enhancement of cement composite: Review and prospects

The interest in utilizing nanopowders in concrete to increase the mechanical characteristics of concrete, such as compressive strength and tensile strength, is gaining importance. The commonly used nanopowders to enhance composite properties are nano-SiO2 (nano-silica), nano-Fe2O3 (nano-ferric oxide), nano -TiO2 (nano-titanium oxide), nano clay, nano-Al2O3 (nano-alumina). Nanopowders are the perfect additive due to their smaller size (1 nm to 100 nm), high level of reactivity, and greater surface area than cement. Hence, the mechanical characteristics of cement-based materials with embedded nanopowders are reviewed in this article. By virtue of the low water-to-cement ratio, nanopowders are utilized to upgrade the strength and workability of the concrete. The review examined the impact of nanopowders on the enhancement of the strength, durability, and cost-effectiveness of concrete. Due to its strong reactivity, nanopowder increases the mechanical (compressive strength, flexural strength, tensile strength, and modulus of elasticity) and durability (resist weathering action, abrasion, chemical attack) properties of the cement composite. The addition of nanopowders to concrete increases the pozzolanic content and surface energy of the cement composite, resulting in the durability enhancement of the cement composite. This article explored that incorporating nanoparticles into concrete enhances its strength by 25 to 40 % on the seventh day and 7 to 14 % on the 28th day, as well as enhances the workability of the cement composite. However, the excessive concentration of nanoparticles causes particle agglomeration, which decreases the strength and durability of the cement composite. Thus, the review concludes that using nanomaterials in concrete is more favorable concerning of strength and durability advancement of the composite, as it improves their qualities and accelerates the hydration process.

Mitigation of Fine Sand Erodibility Using Nano Clay Additives

Mitigation of Fine Sand Erodibility Using Nano Clay Additives

Effect of elevated temperatures on the compressive strength of nano-silica and nano-clay modified concretes using response surface methodology

In this paper, the effect of elevated temperatures of nano-modified concrete mixtures on compressive strength is investigated. Response surface methodology (RSM) was utilized to construct prediction models and perform multi-objective optimization by maximizing the compressive strength of modified concrete with nano-silica (NS) and/or nano-clay (NC) as partial cement substitutions in concrete at various dosages of (1–4 %) and (1–9 %), respectively, and a hybrid inclusion of both NS and NC as cement partial substitutions in concrete subjected to temperatures ranging between 25 °C and 800 °C for 1 and 2 h. Experimental data from 208 cubic specimens with dimensions of 100 × 100 × 100 mm, which were obtained from the literature were used as the database for the developed predictive models to assess the influence of curing ages and various temperatures on the compressive strength of modified nano-concrete. The proposed models were evaluated and validated for their significance and adequacy, and the contribution of each parameter was examined utilizing ANOVA and other statistical criteria. The best correlations were found between compressive strength and substituting NS and/or NC for cement. The optimum cement replacement levels with nanoparticles and temperature for maximizing the compressive strength of concrete were defined using numerical optimization. The results from the developed models were in good agreement with the experimental data.

Rheological and mechanical properties of 3D printable alkali-activated slag mixtures with addition of nano clay

Alkali-activated slag mixture (AAS) is seen as a prospective option to replace Portland cement for three-dimensional (3D) printing to reduce carbon emission. This paper investigates the use of nano clay and adjusting SiO2/Na2O (Ms value) of an alkaline solution to meet the demands for the additive manufacturing process, such as pumpability and buildability. Results showed that the use of nano clay can considerably improve the structural build-up of AAS mixtures. The dynamic and static yield stress of AAS mixtures declined as Ms value of the activator increased. In terms of mechanical properties, the compressive strength increased with an increase of Ms value, while the flexural strength decreased slightly as Ms value increased. A higher Ms value can result in a lower porosity, but more micro-cracks. The mixture with Ms value of 0.8 and 1% nano clay addition was found to be the most suitable for 3D printing as it had greater buildability during printing with less bottom deformation, and had higher strength and lower porosity in the later stages. The main reaction product for the AAS mixture is found to be the C-A-S-H gel with a chain-like structure.

Use of Clay and Titanium Dioxide Nanoparticles in Mortar and Concrete—A State-of-the-Art Analysis

In the past decades, nanomaterials have become one of the focal points in civil engineering research. When added to cement-based construction materials (e.g., concrete), it results in significant improvements in their strength and other important properties. However, the final mix characteristics depend on many variables that must be taken into account. As such, there is no general consensus regarding the influence upon the original material of certain nano-sized additives, the optimum dosage or the synergistic effect of two or more nano-materials. This is also the case for titanium dioxide (TiO2) and nanoclay (NC). The paper focuses on reporting the existing research data on the use of the above-mentioned materials when added to mortar and concrete. The collected data is summarized and presented in terms of strength and durability properties of cement mortar and concrete containing either TiO2 or NC. Both nano-materials have been proven, by various studies, to increase the strength of the composite, at both room and elevated temperature, when added by themselves in 0.5%~12% for TiO2 and 0.25%~6% for NC. It can be inferred that a combination of the two with the cementitious matrix can be beneficial and may lead to obtaining a new material with improved strength, elastic and durability properties that can be applied in the construction industry, with implications at the economic, social and environmental levels.

Preparation of poly (PVP/acrylamide/glycerol/bentonite clay) nanocomposite films by gamma radiation for removal of Sandolane Rubinole Acid Red 37 dye

ABSTRACT The present study focuses on utilising gamma irradiation to prepare Poly (PVP/acrylamide/glycerol/bentonite clay) nanocomposite film poly(PVP/AAm/Glyc/BNTN) with composition (40/60/5/0.25 wt %) at different doses of 10, 20, 30 and,40 kGy. The FTIR analysis shows the successful preparation and modification of the different irradiated poly(PVP/AAm/Glyc/BNTN) nanocomposite film at different doses. The film irradiated at 40 kGy is a stable film that has higher water resistance properties than other prepared films as shown in the swelling study. The bentonite nano clay was found to be homogeneously and well distributed in the surface of the nanocomposite film modified at 40 kGy, which led to the chemical stability of the synthesised poly(PVP/AAm/Glyc/BNTN) with composition (40/60/5/0.25 wt %) as shown in the swelling study, and field emission scan electron microscope (FESEM). Also, the bentonite nanoparticles have an average particle size of 76.5 nm. The impacts of the different factors which include pH, contact time (h.), and temperature (k) on the uptake of Acid red 37 (AR 37) dye from its aqueous solution were investigated. The Langmuir model was established as the suitable model for this work and the uptake of AR 37 dye was designated by the pseudo-second-order kinetic model to be spontaneous and endothermic. Furthermore, the adsorption capacity was enhanced with the temperature and time and reduced with increasing the pH of the dye solution. The maximum adsorption capacity of Poly(PVP/AAm/Glyc/BNTN) samples to the anionic AR 37 dye was found to be 136.13 mg/g at pH 4, contact time 8 hrs, and amount of adsorbent 0.3 g/100 ml of the dye solution.

Optimized multilayer coating using layer-by-layer assembly method for excellent oxygen barrier of poly(lactic acid) based film

Layer-by-layer assembly (LbL) of trilayer coatings of polyelectrolytes and nanoclays (NC) were produced on poly(lactic acid) based (PLAb) films. The focus of this study was on the optimization of the wetting properties of the PLAb substrate, and the adhesion properties of the prepared coating. Coatings produced by an optimized method, by combining UVC-treatment of the substrate and adjusting surface tension of the coating solutions, were compared to coatings made by typically used water-based solutions. Even though LbL-coatings with a high adhesion strength to its substrate is of outmost importance for most applications, this is often not evaluated. In this study, the adhesion of the coatings on the PLAb substrate was assessed using the cross-cut test according to ISO 2409, in which the adhesion is classified on a scale between 0 and 5, where a lower number reflects better adhesion. The coating prepared by the optimized procedure was categorized as class 0, while the control film was classified as 4. These results reveal the importance of the optimization of both the surface free energy of the substrate, and the surface tension of the dipping solutions. The surface morphology and roughness properties of the optimized films were further investigated with scanning electron microscopy (SEM), confocal optical microscopy (COM) and atomic force microscopy (AFM), showing a uniform distribution of NC on the substrate with increasing number of trilayers. X-ray photoelectron spectroscopy (XPS) confirmed the homogenous surface composition of polyelectrolytes and NC. Finally, the oxygen transmission rate (OTR) decreased considerably (by 99.7%), from 97.2 cc/(m2·day) for pristine PLAb substrate to 0.3 cc/(m2·day) for the 20-trilayer coated substrate.

Fused Deposition Modeling of Single-Use Plastic Alloy

Packaging plastics are called ‘single-use plastics’ because of short lifetime. Among which, the three plastics of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) take more than 70%. Due to incompatibility, few research has been done on the alloy of the three plastics. The aim of this study is to investigate the possibility of single-use plastic alloy (SUPA) of ternary PE, PP, and PET as the 3D printing material. Tensile and bending tests are carried out to investigate the mechanical properties, photographs of scanning electron microscope (SEM) are taken for morphology analysis, and differential scanning calorimetry (DSC) are used to study the crystallization behavior of the alloys. The results show that there is an optimal ratio for all the components to obtain the best mechanical performances, i.e., the ratio ofPP/PE=40/60with 20 wt% PET, 2 wt% maleic anhydride grafted polypropylene (PP-g-MAH) and 2 wt% organic modified montmorillonite (OMMT). This SUPA has a tensile strength of 14.48 MPa, a tensile modulus of 586.42 MPa, a flexural strength of 15.85 MPa, and a flexural modulus of 544.67 MPa. Due to the function of compatibilizer and nanoclay (NC) will be affected by redundancy, the potential primary fibrosis while collecting the feeding filaments and the secondary fibrosis at the nozzle of 3D printing might be responsible for the variation of the mechanical performances.

Manipulation of mechanical and thermal properties of graphene oxide/nanoclay/unsaturated polyester hybrid nanocomposites by the surface chemistry and nanofiller composition

Dispersion of platelet-like nanominerals in low-viscous resins is a serious challenge; which arises from the strong interactions among the large surface area of the layers. Herein, we improved the dispersion of graphene oxide (GO) within unsaturated polyester (UP) resin and synergistically enhanced the mechanical and thermal properties of the resulting nanocomposites. In a multi-stage manner, GO was incorporated into a novel hybrid structure before adding to the polymer matrix alongside with benefited from the advantage of surface functionalization. Functional hybrid nanofiller skeletons comprising GO and nanoclay (NC) were designed and prepared at different composition ratios (25:75, 50:50 and 75:25) and different surface chemistries via modification with two thermal-resistant silane coupling agents, namely (3-Aminopropyl) triethoxysilane (APTES) and 3-(trimethoxysilyl) propyl methacrylate (MPS). The optimal loading of different hybrid structures into UP has been examined by applying three loading levels (0.25, 0.50 and 1.00 wt%). The results indicated the synergistic effects of GO and NC on the mechanical properties of UP, where the composition ratio of the hybrid constituents played a key role. Moreover, it was demonstrated that the range of composition ratio for the realization of synergistic reinforcement is strongly affected by the surface chemistry of the GO and NC. For UP matrix reinforced with APTES-modified hybrid nanofillers of GD:CD at 50:50 w/w composition, a higher tensile modulus compared to blank UP (≈+21.5%) was obtained due to boosted dispersion of nanoplatelets in UP matrix. The results of DMTA and TGA analyses suggested that there are two different UP/GO and UP/NC interfacial interactions in the composites containing unmodified hybrid nanofillers. However, after modification of hybrid nanofillers, the homogeneous dispersion of nanoplatelets boosted the interfacial interactions between nanofillers and polymer, such that higher properties were obtained.

Theoretical and experimental investigation of selective gas permeability in polystyrene/polyolefin elastomer/nanoclay nanocomposite films

Nanoclay (NC) has gas barrier properties that, when used in food packaging, protects food against spoilage. Moreover, food packaging frequently makes use of rigid and foamed polystyrene (PS). In this work, reactive blending in a co-rotating twin-screw extruder was used to process PS, polyolefin elastomer (POE), and NC blends, leading to microphase-separated PS/POE/NC nanocomposite films. The structural and CO2 and N2 barrier properties of the resulting films were determined. The distribution of the NC platelets in the blends was theoretically predicted using the wetting coefficients. Nearly all NC platelets were found in the PS phase, in agreement with the theoretical predictions. Moreover, the NC platelets were found to be concentrated at the interfacial zones between the polymer phases when a compatibilizer was added to the blend. Scanning electron microscopy, wide-angle X-ray scattering, and transmission electron microscopy were used to examine the microstructure of the PS/POE/NC nanocomposites. Adding NCs as a gas barrier component to the PS/POE blend resulted in a decrease in CO2 and N2 permeability. For a better understanding of the gas diffusion in the pure PS and POE, as well as PS/POE blend, molecular dynamics simulations were performed to enable the calculation of gas diffusion coefficients in the different systems. The simulation results confirmed the experimental trends observed in this work.

Effect of nanomaterials on the durability of hot mix asphalt

Traffic volume and loads have increased significantly in recent years, coupled with the high summer temperature and the low temperature in winter, premature failure in asphalt concrete pavement becomes the main challenge for pavement construction companies and engineers. The use of modifiers in asphalt concrete mixes become of considerable interest in the improvement of pavement performance and service life. With the advent and evolvement in nanotechnology, many researchers focused on how these materials could serve in rising the serviceability of pavement in terms of reducing rutting, fatigue cracking as well as moisture induced damage. In this study, nanomaterials, including nano silica (NS), nano carbonate calcium (NCC), nano clay (NC), and nano platelet hydroxyapatite (NP), were used to examine the prospect of enhancing the durability and resilience of asphalt mixtures. Specifically, this study aimed to evaluate the effect of adding nanomaterials as a modifier to the bitumen on the Marshall properties, resilient modulus as well as the durability of the asphalt concrete mixture, which was assessed for moisture susceptibility using indirect tensile strength (ITS) and permanent deformation using the uniaxial repeated load test. The investigated nanomaterial dosages were as follows; NS (1, 3 and 5%), NCC (2, 4 and 6%), NC (3, 5 and 7%), and NP (2, 4 and 6%), by weight of asphalt cement. The results were compared with the control mix (CM), i.e., an unmodified mix. The results revealed that nanomaterials significantly improved the properties of asphalt concrete. Also, this work provides a basis for producing more durable mixtures with higher resistance to distress.