Nano SiO2 Research Articles

Effect of melting temperatures on the orientation and rheology of polyacrylate/silica (PAcr/SiO2) composite microspheres in twin‐screw extruder

AbstractThe dispersion and orientation arrangement of functional polymers with fillers are critical to their performance. However, there are rare detailed researches on the visualization of the orientation process about functional fillers in composite melts and the mechanistic effects on performance. In this work, it explored the change process of the orientation morphology for polyacrylate/silica (PAcr/SiO2) composite microspheres in polymethyl methacrylate (PMMA) at different melting temperatures. Afterwards, the morphology and distribution of oriented microfibers in composite fibers melted at different temperatures were observed by transmission electron microscope (TEM). The results showed that composite microfibers could be formed in tight arrangement and obtained average orientation of 50.88 in the composite fibers at 250°C. Under this circumstance, the addition of nano SiO2 particles had no effect on the rheological type. Meanwhile, the shear stress was 99.29% higher than that of pure PMMA system under the same conditions. As for the elongation at break, it was found that the elongation at break of the composite fiber prepared at 250°C was 169.43% higher than that of pure PMMA. Therefore, it provided a new method to achieve well dispersion of functional fillers in molten systems. Furthermore, it was beneficial to enhance the elongation at break of functional composites.

Silanizing nano SiO2 and its application in recycled nitrile rubber to prepare super oil resistant/superhydrophobic/superoleophilic oil/water separator

Polymer wastes and oil slicks are environmental threats in the present century. Accordingly, the reuse of polymer wastes to absorb oil slicks could be an interesting topic. In this research, devulcanized nitrile rubber (DNBR) as oil resistant/recycled material were used to prepare an environmental friendly superhydrophobic/superoleophilic oil sorbent. For this purpose, silica nanoparticles were silanized using vinyltriethoxysilane. HR-TEM, FTIR and XPS analysis were performed to characterize the surface morphology and chemical composition of the pure and silanized nanoparticles. The grafted nano silica illustrated superhydrophobic behavior due to water droplet contact angle which was 156 compared to 53° for pure nano silica. XPS analysis showed that the content of Si, O and C elements on the surface of modified nano silica increased by 18%, 8% and 25%, respectively, compared to pure nano silica. The chemo-thermo-mechanical properties of the DNBR nanocomposites contained 6 phr of pure and silanized nanoparticles were evaluated. Results confirmed improvement in the curing and mechanical performances of the rubbery nanocomposite due to silane grafting. The modified nanocomposite had the highest oil absorption capacity over 2.4 g.g− 1 (i.e. for dense sheet). It efficiently separated about 91% of Persian Gulf oil/water mixtures with remarkable reusability of about 700 cycles.

Synergistic effect of surfactant and chlorine salt on dispersion of nano-SiO2 and performance of cement-based grout containing a large amount of bentonite

Nano-SiO2 (NS) is widely used to improve the performance of cement-based grouts. The workability and mechanical property of grouts are greatly affected by NS dispersion. In this paper, synergistic effect of surfactants and chloride salts on NS dispersion, as well as on performance of grouts including fluidity, mechanical and microscopic properties were systemically studied. The results showed that the synergistic effect of anionic surfactant (SDS) and chloride salt can effectively improve NS dispersion because of the massive formation of micelles that can encapsulate NS and the electrostatic repulsion between micelles. And the effect of CaCl2 was more significant than NaCl. Furthermore, fluidity of fresh slurry and mechanical property of hardened grouts were also improved by the synergistic effect. The mechanical property enhancement might be attributed to the filling effect of NS due to its improved dispersion, and to the matrix compaction associated with the formation of strätlingite and Friedel's salt.

Thermal and Waterproof Properties of Foamed Concrete with Nano SiO2 Aerogel and Organosilicon Waterproofing Agent

This paper aimed to improve the thermal and waterproof properties of foamed concrete through the synergic work of nano SiO2 aerogel powder (NSAP) and organosilicon waterproofing agent (OWA). Hence, several series of foamed concrete with a 0–3.0% of OWA and with 1–4% of NSAP addition were developed. The results show that OWA can decrease the dry bulk density, compressive strength, water absorption rate, and thermal conductivity. With the addition of NSAP, the water absorption rate reached a minimum value of 9.2% at 3.0% NSAP, while the thermal conductivity continued decreasing. Through the microscopic pore size distribution, XRD, and SEM, it was found that the addition of NSAP had no effect on the type of hydration product, but it can increase the average pore size and the amount of macropore and weaken the interfacial adhesion between hydration products. Comparing the heat transmission model, the presence of NSAP increased the heat transmission pathway and resistance, resulting in lower thermal conductivity.

Shrinkage behavior and mechanical properties of alkali activated mortar incorporating nanomaterials and polypropylene fiber

Blended ground granulated blast slag (GGBS), low-calcium fly ash (FA), nano silica (NS), and nano alumina (NA) with/without polypropylene fiber (PPF) had a significant effect on the development length of alkali activated mortar (AAM) cured at various humidity levels and curing ages. This paper presents the behavior of alkali activated mortar with 50% FA and 50% GGBFS binder materials and the alkali ratio of sodium silicate to sodium hydroxide (SS/SH) is 2.5. The molar concentration of sodium hydroxide (NaOH) used was 12 M. Feasibility Comparisons between the different humidity 60%–98% of at 23 ± 3 C° were examined. The strength behavior of alkali-activated mortar with different curing ages was also evaluated. Scanning electron microscopy (SEM) analysis and X-ray diffractions (XRD) were also conducted to clarify the effect of nanomaterials and PPF on the microstructures of AAM. It was found that the shrinkage values of AAM were decreased with the addition of polypropylene fiber and nanomaterials. The combined use of both nanomaterials had better performance than the use of nano SiO2 and/or nano Al2O3 alone. The combined use of PPF with nanomaterials had a superior reduction in shrinkage and expansion and increment on strength values; the minimum shrinkage, expansion values, and maximum strength were found at AAM mix incorporating 2%NS-1%NA-0.5%PPF. The SEM analysis and XRD evaluation indicates the significant effect of nanomaterials on the microstructures and bond strength of AAM. The microstructure of the mixes incorporating both nanomaterials and PPF was denser than other mixes without nanomaterials and/or PPF and showed lower micro cracks.

Nano SiO2 catalytic synthesis, NMR spectral studies, photophysical properties and theoretical studies of some styryl imidazole derivatives

New styryl imidazole derivatives were prepared by using nano SiO2 catalyst and proved it catalytic efficiency. Diminutive reaction time, high yield of the imidazole derivatives and a variety of substitute reactant usage were accomplished by using nano SiO2 catalyst. Solvatochromism of newly synthesized imidazole derivatives have been studied by using Marcus and Reichardt – Dimroth solvent functions. When polarity of the solvent was increased, the absorption position of synthesized styryl imidazole derivatives shifted to higher wavelength, that is bathochromic shift was fashioned. Emission band maxima these imidazole derivatives also shifted to the longer wavelength, which was due to dielectric solute and solvent interactions. HOMO–LUMO energies of imidazole derivatives have been calculated by DFT calculations at B3LYP/6-31G (d, p) using Gaussian-03.

Fabricating multi-porous carbon anode with remarkable initial coulombic efficiency and enhanced rate capability for sodium-ion batteries

Due to the abundant sodium reserves and high safety, sodium ion batteries (SIBs) are foreseen a promising future. While, hard carbon materials are very suitable for the anode of SIBs owing to their structure and cost advantages. However, the unsatisfactory initial coulombic efficiency (ICE) is one of the crucial blemishes of hard carbon materials and the slow sodium storage kinetics also hinders their wide application. Herein, with spherical nano SiO2 as pore-forming agent, gelatin and polytetrafluoroethylene as carbon sources, a multi-porous carbon (MPC) material can be easily obtained via a co-pyrolysis method, by which carbonization and template removal can be achieved synchronously without the assistance of strong acids or strong bases. As a result, the MPC anode exhibited remarkable ICE of 83% and a high rate capability (208 mAh/g at 5 A/g) when used in sodium-ion half cells. Additionally, coupling with Na3V2(PO4)3 as the cathode to assemble full cells, the as-fabricated MPC//NVP full cell delivered a good rate capability (146 mAh/g at 5 A/g) as well, implying a good application prospect the MPC anode has

Fabrication of eco-friendly and efficient flame retardant modified cellulose with antibacterial property

Flame retardant and antibacterial investigation of cellulose has attracted more and more attention. In order to improve the modification efficiency, inspired by multiple hydrogen bonding in spider silk, flame retardant and antibacterial dual function modified cellulose was achieved by multi structure hydrogen bonding in this research. A novel nano SiO2 based Schiff base flame retardant (SiAPH) and dodecyl quaternary ammonium salt (HDAC) were synthesized. Tannin (TA) was introduced as medium to provide synergistic flame retardant and antibacterial with SiAPH and HDAC. The flame retardancy assessment demonstrated that the limiting oxygen index (LOI) of modified cotton fabrics increased from 18% to 26.1%, and the peak of heat release rate (pHRR) decreased by 41.0%, UL-94 vertical combustion proved the modified cotton fabrics had capability of self-extinguishing. The antibacterial of modified fabrics were confirmed against Staphylococcus aureus and Escherichia coli, and the inhibition rate reached to 99.1%. In addition, it worth noting that the biocompatibility and antibacterial activity of modified fabrics were evaluated via MTS assay and establishment of animal wound model. Low toxicity of the fabrics was verified by the L929 fibroblast cells. The anti-infection experiment model showed that the modified fabrics had a positive effect on prevention of infection, and the wound healing rate reached to 86.8% after 14 days’ treatment. The flame retardancy, antibacterial and biocompatibility of the functional cotton fabrics indicated that they were ideal candidate for applications of vehicle interior, soft decoration in public and medical scene.

Poly (ethylene terephthalate) nonwoven fabrics‐based membranes modified by electrospinning of thermoplastic polyurethane, nano SiO2 and Ag particles as medical packing materials

AbstractAiming at development of novel medical packings, poly (ethylene terephthalate) (PET)‐based membranes with hydrophobic and antibacterial properties were prepared by electrostatic spinning of a blend of thermoplastic polyurethane (TPU), nano SiO2 and Ag particles on PET nonwoven. In cooperation with electro‐spun TPU/SiO2 layer, the water contact angle (WCA) of PET nonwoven fabric was improved from 60° to 115–130°, and the water vapour transmission rate was 2200–2500 g/m2/24 h. It indicates that the modified PET nonwoven membrane exhibits a much better water resistance, highly increased hydrophobicity and moderate water permeability. Nano‐silver provided excellent antibacterial properties for this non‐cytotoxic PET/TPU/SiO2/Ag composite membranes. The PET/TPU/SiO2/Ag composite membranes had high mechanical properties, which exhibited a tensile strength of 56 MPa in the longitudinal direction and 35 MPa in the transversal direction, and tear strength of 30 kN/m in the longitudinal direction and 48 kN/m in the transversal direction. This new PET/TPU/SiO2/Ag composite membranes showed broad application prospects in the medical packaging industry.

Utilizing Nanotechnology to Solve Drilling Problems in Iraqi Oil Fields

Nanotechnology is a recent technology which is used in all industry sectors. In the oil and gas industry, this technology is commonly used due to its importance in solving the problems encountered while drilling operations and production stages. Nanotechnology can be used to improve the drilling process by adding nano-materials to drilling fluids in order to reduce drilling problems. This research is extended to previous research that published in journal of petroleum research and studies to compared the effect of nano-materials [Commercial nano-materials Multi Walled Carbone Nano Tube (MWCNT) and nano silicon oxide (SiO2) with nano-silica (rice husks, that prepared in PRDC labs) on water base drilling mud properties].
 All characterization tests were achieved by the Nanotechnology and advanced materials researches center it is belongs to the University of Technology. The investigated properties of drilling mud included rheological properties and filtration. All tests are conducted according to API specifications (American Petroleum Institute).
 The results show an improvement in the rheological properties (plastic viscosity, yield point, apparent viscosity and gel strength) and filtration after adding the commercial MWCNT, nano silicon dioxide(Sio2) and the prepared nano-silica (rice husks) to the water based mud. The results of plastic viscosity of MWCNT,Sio2 and nano silica(rice husks) are 12,20,8 cp after adding 0.7 gm to the water base mud while the amount of filter is 11.8 ml after adding nano particle size of MWCNT , nanoSio2 and 11.6 after adding nano silica(rice husks). The prepared nano silica (rice husks) gave results similar to the results of the commercial nano silicon dioxide (SiO2). Therefore, using of nano silica (rice husks) can be cost effective due to producing these materials locally instead of using the commercial nano SiO2.

Effect of Nano SiO2 Enhanced Polyurethane Road Grouting Material on Folding Strength and Durability of Road Concrete

Effect of Nano SiO2 Enhanced Polyurethane Road Grouting Material on Folding Strength and Durability of Road Concrete

Compressive strength and anti-chloride ion penetration assessment of geopolymer mortar merging PVA fiber and nano-SiO2 using RBF–BP composite neural network

Abstract In this study, we investigated the mechanical properties and chloride ion permeation resistance of geopolymer mortars based on fly ash modified with nano-SiO2 (NS) and polyvinyl alcohol (PVA) fiber and metakaolin (MK) at dose levels of 0–1.2% for PVA fiber and 0–2.5% for NS. The Levenberg–Marquardt (L–M) back propagation (BP) neural network, as well as the radial-based function (RBF) neural network, was used to predict the compressive strength and chloride ion permeation resistance of the geopolymer mortar with different admixtures of nanoparticles and PVA fiber, wherein the electric flux value was used as the index for chloride ion permeation performance. The RBF–BP composite neural network was constructed to study the compressive strength and chloride ion permeation resistance of nanoparticle-doped and PVA fiber ground geopolymer mortars. According to the experimental results of the RBF–BP composite neural network model, the mean square error (MSE) was observed to be 0.00071943, root mean square error (RMSE) was 0.026822, and mean absolute error (MAE) was 0.026822, thereby showing higher prediction accuracy, faster convergence, and better fitting effect compared with the single BP neural network and RBF neural network models. In this study, we combined the RBF–BP composite artificial neural network, providing a new method for the future assessment of the compressive strength and chloride ion penetration resistance of geopolymer mortar merging PVA fibers and NS in experiments and engineering studies.

Ni/NiO/SiO2/C nanofibers with strong wideband microwave absorption and robust hydrophobicity

Multifunctional microwave absorbers with robust hydrophobicity and enhanced wave absorption are of great significance for human health and the martial applications. Herein, carbon nanofibers (CNFs) inlaid with Ni/NiO and SiO2 nanoparticles were prepared by electrospinning and in-situ annealing method. Contrast experiments at different annealing temperatures had been conducted to illustrate the formation process and microwave loss mechanism of Ni/NiO/SiO2/CNFs. At the annealing temperature of 550 °C, the optimal reflection loss (RL) of −40.1 dB was reached at 16.6 GHz with a thickness of 2.5 mm, the effective absorption bandwidth (EAB) was 5.2 GHz. The maximum EAB of 8.0 GHz was obtained as the thickness close to 3.0 mm, covering the half of X band and entire Ku band. It was worth mentioning that the introduction of nano SiO2 into the Ni/NiO/CNFs annealed at 550 °C could refine the nanoparticles of Ni, promote the formation of Ni, improve the complex permittivity, and ultimately widen the EAB. Moreover, the contact angle (CA) of the Ni/NiO/SiO2/CNFs membranes annealed at 450, 550, 650 and 750 °C was 154.3°, 138.7°, 142.2° and 144.9°, respectively, illustrating that the products were of robust hydrophobicity. Therefore, the as-prepared NFs are promising in multifunction wave absorbers.

Fly Ash-Added, Seawater-Mixed Pervious Concrete: Compressive Strength, Permeability, and Phosphorus Removal.

A mix proportion of off-spec fly ash (FA)-added, seawater-mixed pervious concrete (SMPC) was optimized for compressive strength and permeability and then the optimized SMPC was tested for the rate and extent of aqueous phosphorus removal. An optimum mix proportion was obtained to attain the percentages (% wt.) of FA-to-binder at 15.0%, nano SiO2 (NS)-to-FA at 3.0%, liquid-to-binder at 0.338, and water reducer-to-binder at 0.18% from which a 7-day compressive strength of 14.0 MPa and a permeability of 5.5 mm/s were predicted. A long-term maximum compressive strength was measured to be ~16 MPa for both the optimized SMPC and the control ordinary pervious concrete (Control PC). The phosphorus removal was favorable for both the optimized SMPC and the Control PC based on the dimensionless Freundlich parameter (1/n). Both the optimized SMPC and Control PC had a first-order phosphorus removal constant of ~0.03 h−1. The optimized SMPC had a slightly lower capacity of phosphorus removal than the Control PC based on the Freundlich constant, Kf (mg1−1/n kg−1 L1/n): 15.72 for the optimized SMPC vs. 16.63 for Control. This study demonstrates a cleaner production and application of off-spec FA-added, seawater-mixed pervious concrete to simultaneously attain water, waste, and concrete sustainability.

Preparation of a novel vitrified bond CBN grinding wheel and study on the grinding performance

The vitrified bond CBN grinding wheels are characterized by high efficiency, high precision, and low environmental pollution. In recent years, the vitrified bond CBN grinding wheel has been widely used in manufacturing industries such as aerospace, automotive, and machine tools. In this study, a novel vitrified bond formulation containing nano SiO2 and nano CeO2 is selected to prepare the grinding wheel. The grinding experiments on 45# steel and YG20 alloy indicate that the grinding performance of the nano vitrified bond grinding wheel is significantly better than that of the conventional vitrified bond grinding wheel. The introduction of nano SiO2 and nano CeO2 greatly improves the machining performance of the vitrified bond CBN grinding wheel.

Physical and mechanical properties of hybrid composites using Kevlar fibre and nano-SiO2

ABSTRACT The current study aims to examine the mechanical and physical properties of Kevlar fibre/nano-silica/epoxy hybrid composites. The hand layup process followed by compression moulding was used to prepare a hybrid composite with different weight percentages (0%, 1%, 3%, and 5%) of nano SiO2 and four layers of the Kevlar fibres. Hardness, flexural, tensile, and impact tests were performed to evaluate mechanical properties. Nano SiO2 and Kevlar fibre improve the mechanical properties of the hybrid composites up to 3 wt.%. Rockwell Hardness tests suggest that the hardness of composites (K3) has improved up to 29% compare to K0. Tensile strength is about double at 3 wt.% nano SiO2 compared to neat laminates. The K3 has highest impact strength has increased by 50%. Flexural properties also increase up to 3 wt.% nano SiO2 reinforcement. Density, water absorption, and thickness swelling test wear were performed for the evolution of physical properties. Morphological analysis was done with the help of the field emission scanning electron microscopy (FESEM) technique.

Enhancing the heat transfer and photothermal conversion of salt hydrate phase change material for efficient solar energy utilization

Solar energy is intermittent, resulting in a discrepancy between the solar energy supply and building energy demand. Salt hydrate phase change material (PCM) is a promising material for use as an energy storage medium, but it suffers from a high supercooling degree, low thermal conductivity, and insufficient photothermal conversion efficiency. In this work, a novel sodium acetate trihydrate (SAT) composite was developed by synergistically using nano SiO2 (NS) as the nucleating agent, silicon carbide (SiC) foam as the thermal conductivity enhancer, and carbon nanotubes (CNT) as the photothermal enhancer. The supercooling degree of the modified SAT composite was only 1.4 °C, whereas the thermal conductivity and photothermal conversion efficiency could be increased to 1.54 W/(m•K) and 94.2 %, respectively. Most importantly, the payback period for applying the modified SAT composite in solar energy storage for domestic hot water supply is only 3.1 years, and the carbon dioxide emission could be reduced by approximately 1379.1 kg CO2-eq/year for a typical four-person family. Overall, the modified SAT composite with stable and excellent thermophysical properties offers great potential for the storage of solar thermal energy.

Application of Nano SiO2 in Pervious Concrete Pavement Using Waste Bricks as Coarse Aggregate

Application of Nano SiO2 in Pervious Concrete Pavement Using Waste Bricks as Coarse Aggregate

The Effect of Active Additives and Coarse Aggregate Granulometric Composition on the Properties and Durability of Pervious Concrete.

Pervious concrete (PCO) has many advantages and applications, such as water pooling reduction, noise attenuation, replenishment of groundwater reserves, etc. However, the use of pervious concrete is limited due to its low compressive strength and durability, especially as a result of portlandite leaching from concrete exposed to flowing water. The effects of active additives (nano SiO2 (NS) spent catalyst generated at the fluid catalytic cracking unit (FCCCw) and paper sludge waste burned at 700 °C (PSw)) along with particle size distribution of the coarse aggregate on the properties and durability of pervious concrete were determined in the research. Active additives used in the binder were found to reduce portlandite leaching from concrete exposed to flowing water to significantly increase the resistance of concrete to freezing and thawing cycles and to increase sound absorption, compressive strength and infiltration rate. In addition, industrial waste (FCCCw and PSw) used as active additives significantly reduced the use of clinker in concrete applied in the construction of water pervious systems. The coarse aggregate size distribution had the greatest effect on the density, ultrasound pulse velocity (UPV), porosity, compressive strength and infiltration rate of pervious concrete.

Rotatory flow of MHD (MoS2-SiO2)/H2O hybrid nanofluid in a vertical channel owing to velocity slip and thermal periodic conditions

BackgroundThe present article is a mathematical study on oscillatory pressure-driven MHD flow of a hybrid nanofluid in a vertical rotating channel. Hall current effect along with velocity slip and thermal periodic boundaries are the main focus of the present mathematical analysis. In the present investigation Molybdenum disulfide and silicon dioxide, nano-scaled particles are suspended in water. MethodologyMathematical modeling is carried out by considering rotating frame in the rectangular coordinate system and suitable non-dimensional variables are incorporated for simplification and non-dimensionalization of the problem. The hybrid nanofluid velocity and temperature distributions are derived in closed form with the aid of mathematics software MATHEMATICA. The prominent parameters’ effect on flow and heat transfer is investigated and studied through graphs. Significant findingsIt is concluded that hybrid nanofluid transport is highly influenced by surface roughness within the channel. Mixed convection and rotation parameters contribute to decelerating primary velocity and accelerating secondary velocity for both silicon dioxide as well as MoS2−SiO2 nano and hybrid nanofluids, respectively.