Presence Of Nanosilica Research Articles

Epoxy-Polyester/Nano-Silica Hybrid Coating: A New Nanocomposite Candidate for Can Coating

Epoxy resin has been used as can coating material for decades because of its suitable chemical and mechanical properties compared to the other resins. However, usage of this resin has been limited due to the migration of Bisphenol A (BPA) derivatives into the foodstuffs. In the current study, coating material containing mixed polyester and epoxy resins with different amounts of nano-silica particles were prepared. The formulated coating materials were cured in the presence of melamine formaldehyde resin. The curing completion was investigated using Fourier Transfer Infrared Spectroscopy. The mechanical, chemical and thermal properties of cured coatings were investigated based on the standard methods. Thermal stability of all formulated samples was acceptable, and degradation was not observed in the temperature range of sterilization and pasteurization processes. Migration tests containing global migration and BPA migration were performed, and toxicity investigations showed that the concentrations of released materials into the food simulants were in the acceptable ranges, based on the EN1186-EU 10:2011 standard. Results also showed that, in the presence of nano silica, polyester is an appropriate candidate to add into the conventional can coating formulations to replace with a great portion of epoxy.

FTIR Analysis of Nanomodified Cement Concrete Incorporating Nano Silica and Waste Marble Dust

In present study, different compositions of concrete mixes with marble dust and nano-silica have been prepared and studied with Fourier Transform Infrared (FTIR) spectroscopy to evaluate different phases formed during hydration reaction. Formation and extent of phases formed during hydration reaction occurring for different curing days can be successfully correlated with the shifting of FTIR bands in various concrete samples. FTIR results demonstrate the shifting in peaks in presence of marble dust and nano-silica as compared to control mix. Decrease in intensity of Raman bands at 1636 and 3400-3650 cm−1with curing time was observed due to hydration of C3S and C2S. The bands observed at 1475 and 890 cm-1also shift towards lower wave number side 1450-1460 cm−1with increasing nano-silica content. These peaks are correlated with extent of carbonation which gets decreased in the presence of nano-silica. In addition to this, bands corresponding to ettringite, monosulphate and C-S-H molecules at 1180, 1120 and 980 cm−1 also shift towards lower number side with increase in concentration of nano-silica and marble dust.

Evaluation of the nano silica and nano waste materials on the corrosion protection of high strength steel embedded in ultra-high performance concrete

Corrosion resistance of high strength steel (HHS) embedded in ultra-high performance concrete (UHPC) immersed in 3.5% NaCl solution is evaluated in the absence and presence of nano silica (NS), nano glass waste (NGW), nano rice husk ash (NRHA) and nano metakaolin (NMK) using open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) under normal and accelerated conditions. Data showed that the corrosion rate in the accelerated conditions is higher compared by the normal conditions due to the increasing in the rate of both anodic and cathodic reactions in the presence of anodic current. On the other hand, the presence of the studied nano materials decreases both the anodic and cathodic overpotentials, and shifts both the open circuit potential (Eocp) and corrosion potential (Ecorr) of HSS to more noble values, as well as decreases the values of the corrosion current densities (Icorr) in both normal and accelerated conditions. Furthermore, EIS analysis illustrates that the presence of these materials enhances both the concrete bulk resistance and the charge transfer resistance at HSS/UHPC interface, which retards the flow of the electrons between the anodic and cathodic sites, thus impeding the propagation of the corrosion process. The inhibitory effect of the studied nano materials for the corrosion of HSS is interpreted on the basis of the change in the microstructure and the compressive strength of the UHPC.

Hydration Characteristics of Tricalcium Aluminate in the Presence of Nano-Silica.

Tricalcium aluminate (C3A) is the most reactive component of the Portland cement and its hydration has an important impact on the workability and early strength of concrete. Recently, nanomaterials such as nano-silica (nano-SiO2) have attracted much attention in cement-based materials because of its pozzolanic reactivity and the pore-filling effect. However, its influence on the hydration of C3A needs to be well understood. In this study, the hydration kinetics of C3A mixed with different percentages of nano-SiO2 were studied and compared with pure C3A. The hydration products were examined by different characterization techniques including XRD, XPS, and NMR spectroscopy and isothermal calorimetry analyses. The XRD results showed that the addition of nano-SiO2 promoted the conversion of the intermediate product C4AH13. The isothermal calorimetry results showed that the addition of nano-SiO2 significantly reduced the hydration exotherm rate of C3A from 0.34 to less than 0.1 mW/g. With the presence of nano-SiO2, the peaks for Q1 were observed in 29Si MAS-NMR measurements, and the content of Q1 increased from 6.74% to 30.6% when the nano-SiO2 content increased from 2 wt.% to 8 wt.%, whereas the proportion of Q4 gradually decreased from 89.1% to 63.6%. These results indicated a pozzolanic reaction provoked by the nano-SiO2 combined with aluminate structures generating C-A-S-H gel.

Strength and microstructural analysis of nano-silica based cement composites in presence of silica fume

Replacement of cement with pozzolanic materials has addressed numerous inquiries identified with impact of these materials on the microstructural and other properties of cement composites. On the other hand, because of the absence of technique and pertinent supporting information, an appraisal of general execution of such admixtures is hard to be completed. The utilization of pozzolanic materials as cement substitution in mortar has enhanced the execution of their physico-chemical and mechanical properties. In this study, the composition of silica fume (SF) was differed as 3%, 6%, 9% and 12% at a fixed composition of nano-silica (NS) as 0.5% by weight for substitution of cement. The fresh and hardened properties of cement mortars were analyzed and microstructural analysis was performed. The specimens were found to exhibit better developed microstructure and enhanced compressive strength with inclusion of optimized dosage of SF in presence of NS. The study has confirmed that the simultaneous replacement of cement with the optimized dosage of pozzolanic materials brings improvement in the properties of the cement mortar and can be used to partially substitute cement for the beneficiary effects.

The Effects of Temperature Curing on the Strength Development, Transport Properties, and Freeze-Thaw Resistance of Blast Furnace Slag Cement Mortars Modified with Nanosilica.

This investigation studies the effects of hot water and hot air curing on the strength development, transport properties, and freeze-thaw resistance of mortars incorporating low-heat blast furnace slag cement and nanosilica (NS). Mortar samples were prepared and stored in ambient conditions for 24 h. After demolding, mortar samples were subjected to two different hot curing methods: Hot water and hot air curing (40 °C and 60 °C) for 24 h. For comparison purposes, mortar reference mixes were prepared and cured in water and air at ambient conditions. Strength development (from 1 to 180 days), capillary water porosity, water sorptivity, and freeze-thaw resistance were tested after 180 days of curing. The experimental results showed that both curing regimes accelerate the strength development of mortars, especially in the first seven days of hydration. The highest early strengths were reported for mortars subjected to a temperature of 60 °C, followed by those cured at 40 °C. The hot water curing regime was found to be more suitable, as a result of more stable strength development. Similar findings were observed in regard to durability-related properties. It is worth noting that thermal curing can more efficiently increase strength in the presence of nanosilica, suggesting that NS is more effective in enhancing strength under thermal curing.

Tensile and Flexural Properties of Silica Nanoparticles Modified Unidirectional Kenaf and Hybrid Glass/Kenaf Epoxy Composites.

This paper investigates the influence of silica nanoparticles on the mechanical properties of a unidirectional (UD) kenaf fiber reinforced polymer (KFRP) and hybrid woven glass/UD kenaf fiber reinforced polymer (GKFRP) composites. In this study, three different nanosilica loadings, i.e., 5, 13 and 25 wt %, and untreated kenaf fiber yarns were used. The untreated long kenaf fiber yarn was wound onto metal frames to produce UD kenaf dry mat layers. The silane-surface-treated nanosilica was initially dispersed into epoxy resin using a high-vacuum mechanical stirrer before being incorporated into the UD untreated kenaf and hybrid woven glass/UD kenaf fiber layers. Eight different composite systems were made, namely KFRP, 5 wt % nanosilica in UD kenaf fiber reinforced polymer composites (5NS-KFRP), 13% nanosilica in UD kenaf fiber reinforced polymer composites (13NS-KFRP), 25 wt % nanosilica in UD kenaf fiber reinforced polymer composites (25NS-KFRP), GKFRP, 5 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (5NS-GKFRP), 13 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (13NS-GKFRP) and 25 wt % nanosilica in hybrid woven glass/UD kenaf fiber reinforced polymer composites (25NS-GKFRP). All composite systems were tested in tension and bending in accordance with ASTM standards D3039 and D7264, respectively. Based on the results, it was found that the incorporation of homogeneously dispersed nanosilica significantly improved the tensile and flexural properties of KFRP and hybrid GKFRP composites even at the highest loading of 25 wt % nanosilica. Based on the scanning electron microscopy (SEM) examination of the fractured surfaces, it is suggested that the silane-treated nanosilica exhibits good interactions with epoxy and the kenaf and glass fibers. Therefore, the presence of nanosilica in an epoxy polymer contributes to a stiffer matrix that, effectively, enhances the capability of transferring a load to the fibers. Thus, this supports greater loads and improves the mechanical properties of the kenaf and hybrid composites.

Study of the Synergistic Effect of the Nanoparticle-Surfactant-Polymer System on CO2Foam Apparent Viscosity and Stability at High Pressure and Temperature

The goal of this study is to experimentally investigate the stability and rheological behavior of supercritical CO2 foam in the presence of nanosilica, a surfactant, and a polymer. First, three typ...

Physical properties of impregnated sengon wood by monoethylen glycol and nano silica from betung bamboo sticks

Sengon wood (Falcataria moluccana) is a fast-growing species that has low dimensional stability and density. The purposes of this study were to analyze the effect of impregnation treatment by using MEG (monoethylen glycol) and nano silica from betung bamboo sticks on the dimensional stability and density of sengon wood and to identify the characteristics of impregnated sengon wood. The treatments were consisted of untreated (water treated), 50% MEG (MEG), 0.5% nano silica in 50% MEG (MEGsilica 0.5%), 0.75% nano silica in 50% MEG (MEGsilica 0.75%) and 1% nano silica in 50% MEG (MEGsilica 1%). Weight percent gain, anti-swelling efficiency, water uptake, bulking effect, and density were affected by the treatments. It was due to the coverage of MEG and nano silica on cell walls and vessels of sengon wood (SEM analysis). Also, the presence of nano silica in wood treated (SEM-EDX analysis). The cristalinity of sengon wood decreases because MEG is amourphous. FT-IR showed there was no MEG bonds with sengon wood cell wall components or between nano silica and sengon wood. The optimum treatment for sengon wood was MEGsilika 1%.

Modification of water absorption and pore structure of high-volume fly ash cement pastes by incorporating nanosilica

High-volume (>50%) fly ash (HVFA) is used to partially replace cement in concrete to reduce the greenhouse gas emission, which is beneficial to both cement industry and environment. However, one drawback of using high-volume fly ash cement (HVFAC) is the increase of the water absorption and the reduction of the durability of cement-based materials. In this study, the effect of nanosilica (NS) on the compressive strength and water absorption of HVFAC pastes were investigated. In addition, the phase composition, microstructure and pore structure of the pastes were analyzed through X-ray diffraction (XRD), scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). Results showed that the addition of NS increased the compressive strength and reduced the water absorption of HVFAC pastes. NS could react with Portlandite to produce additional C–S–H gel, and simultaneously a higher content of fly ash was hydrated in the presence of NS. Therefore, the incorporation of NS refined the pores and reduced the pore volume of HVFAC pastes. The pores with diameter larger than 10 nm were more pronounced for the water absorption ability of HVFAC composites. This study provided a possible way to reduce the negative effect brought by the increased water absorption when using HVFA in cementitious materials.

Experimental Investigation on Recycled Aggregate with Laboratory Concrete Waste and Nano-Silica

Abstract In the research laboratories a huge amount of concrete specimens are thrown away after their testing or due to some flaws which results in large amount of material loss not only in the initial stage but also after the end result. Therefore, a need to reuse these waste specimens by recycling them into coarse aggregates and then further using it to make concrete will turn into a sustainable option. This paper deals with the study of Recycled aggregate concrete made from laboratory concrete waste replacing Natural Aggregate(NA) and Nano Silica(NS) as partial replacement with cement. In this paper we investigated the compressive strength, split tensile strength, flexural strength for mechanical properties and water sorptivity and rapid chloride penetration to evaluate durability characteristics of control concrete i.e., with natural aggregate as well as 20%, 40% and 60% replacement of NA with Recycled Aggregate (RA). Also, we compared the above results with concrete specimens prepared by replacing 1%, 3% and 5% of cement with Nano silica for each of the 20%, 40% and 60% RA concrete mix. The results indicated that when there was no presence of Nano silica in the specimen and had only RA and NA, a decrease in strength was observed. On the other hand, when Nano silica was replaced with cement, there was a gain in strength. The mix having 3% NS and 40% RA gave an optimum result for strength and durability properties. It also helps in reducing the CO2 emissions which occur due to large amount of cement usage leading to environmental problems like greenhouse effect. Thus, it inferred that replacement of cement with NS acts as an additive and helps in improving the micro-structure of the concrete. Also, it augments the strength and durability characteristics up to 3% replacement level along with 40% replacement of natural aggregate with RA in order to focus on sustainability.

Early age, hydration, mechanical and microstructure properties of nano-silica blended cementitious composites

This study was carried out to understand the influence of nano-silica on hydration properties of binary, ternary and quaternary blended cement paste and mortar containing micro to nano sized admixtures including fly ash (FA), ultrafine fly ash (UFFA) and nano-silica in colloidal form (CNS). Characterization methods such as thermogravimetric analysis (TGA), X-ray diffraction studies (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) was employed to quantify the hydration products. Further, early age and mechanical properties were also investigated for binary, ternary and quaternary cementitious system blended with nano-silica. The optimized proportions of blended paste and mortar are designed through modified Andreasen and Andersen particle packing model.The experimental test results revealed that the optimum dosage of CNS in binary blended cement composites is 3%. The presence of nano-silica in cementitious system amplified the hydration and pozzolanic activity, thereby promoting densified microstructure at nano scale. The flow test indicated the intensified demand for water absorption and reduced workability with the rise in level of incorporation of CNS particles in cement paste. Quaternary blended mix performed superior hydration along with strength properties amongst all the blended samples.

Water repellent finishing on eri silk fabric using nano silica

Nano silica was extracted from rice husk and applied on eri silk fabric to impart water repellency. The efficiency of the water repellency was evaluated with water contact angle, water absorbency and spray test methods. In order to enhance the water repellent properties, a silicone-based polymer was also applied. The effect of nano silica coating on the physico-mechanical properties of the eri silk fabric was studied using standard methods. SEM, FTIR and EDX techniques were used for the confirmation of presence of nano silica on silk fabric. The results inferred the nano silica imparted hydropholic property to eri silk fabric, which was further enhanced to superhydrophobic by the incorporation of silica polymer. The nano silica coating slightly enhanced the whiteness and brightness of eri silk fabric. Other mechanical parameters like bending rigidity and crease recovery angle were found to be intact. The higher concentration of nano silica caused a slight reduction in fabric tensile strength.

Improving the performance of oil based mud and water based mud in a high temperature hole using nanosilica nanoparticles

Oil-based mud (OBM), a non-Newtonian fluid, is known for its superior performance in drilling complex wells as well as combating potential drilling complications. However, the good performance may degrade under certain circumstances especially because of the impact of chemical instability at an elevated temperature. The same phenomenon occurs for water-based mud (WBM) when it is used in drilling under high temperature conditions. To prevent this degradation from occurring, numerous studies on utilizing nanoparticles to formulate smart fluids for drilling operations are being conducted worldwide. Hence, this study aims to evaluate the performance of nanosilica (NS) as a fluid loss reducer and a rheological property improver in both OBM and WBM systems at high temperature conditions. This study focuses on the impacts of different nanosilica concentrations, varying from 0.5 ppb to 1.5 ppb, and different mud weights of 9 ppg and 12 pg as well as different aging temperatures, ranging from ambient temperature to 300 °F, on the rheological performance of OBM and WBM. All the rheological properties are measured at ambient temperature, and additionally tests, including lubricity, electrical stability, and high-pressure high-temperature filtration measurements, are conducted, and rheological models are obtained. The performance of nanosilica is then studied by comparing each of the nanosilica-enhanced mud systems with the corresponding basic mud system, taking the fluid loss and rheological properties as the benchmark parameters. Nanosilica shows a positive impact on OBM and WBM, as the presence of nanosilica in the mud systems can effectively improve almost all their rheological properties.

Experimental investigation of hole cleaning in directional drilling by using nano-enhanced water-based drilling fluids

Inadequate hole cleaning often leads to challenges in drilling and well completion operations such as low rates of penetration, pipe sticking, losing tools, difficulties in liner/casing placements, etc. Designing a drilling fluid with improved rheological properties would be a solution to increase cuttings transportation efficiency. This study investigates the performance of nanosilica water-based drilling fluids for the hole cleaning process in directional drilling operations. Different inclination angles have been considered in a flow loop system with different rotational speeds (0 and 150 rpm) to simulate the drilling conditions in a wellbore. The performance of nano-enhanced drilling fluids in the cuttings removal process was compared with conventional water-based drilling fluids, and it was found that silica nanoparticles increased the cuttings transport efficiency in all experiments. The results indicated that the presence of nanosilica in the mud increased the colloidal interactions with cuttings and contributed to the improvements in cuttings transportation efficiency by 30.8–44% for different nano-enhanced water-based drilling fluids used in this study. The implementation of nanosilica in water-based drilling fluids showed promising results in the hole cleaning process which demonstrates the feasibility of using them in extended reach drilling operations.

Effect of Silica Nanoparticles on Properties of Coatings Based on Acrylic Emulsion Resin

Effect of nanosilica size on physic-mechanical properties, thermal stability and weathering durability of coating based on acrylic emulsion. Nanocomposite coating formulas were filled by 2 wt.% nanosilica particles which were used in this study, namely: nanosilica from Sigma (15-20nm), nansilica from rice husk (~70-200 nm) and nanosilica from Arosil – Belgium (7-12 nm). Obtained results showed that viscosity flow of coating formula containing nanosilica from Arosil saw the highest flow-time while coating formulas filled other nanosilica and unfilled nanosilica experienced similar flow-time. In presence of nanosilica, coating properties were improved in comparison with neat coating. However, coating filled by nanosilica from rice husk indicated the best properties in studied coating formula. It may explained that size of nanosilica from rice husk was the largest in studied nanosilica particles and thus easily dispersing into coating formula.

Experimental Investigation on the Nanosilica-Reinforcing Polyacrylamide/Polyethylenimine Hydrogel for Water Shutoff Treatment

Polyacrylamide hydrogel used in conformance control is subjected to poor stability at an elevated temperature. In this paper, nanosilica has been found to be a very effective stabilizing agent for the polyacrylamide/polyethylenimine hydrogel, and the reinforcing performance of nanosilica on the hydrogel was investigated in detail. The result showed that the strength of hydrogel is enhanced obviously by the nanosilica, and the hydrogel syneresis is also significantly inhibited by the nanosilica, which can increase the hydrogel stability time from 18 to 180 days at 130 °C. Besides, nanosilica can increase the shear viscosity and hydrodynamic radius of polyacrylamide, and the bound water in the hydrogel is also grown in the presence of nanosilica. In comparison to the micromorphology of common hydrogel, the dense and strong mesh structure is formed as a result of the reinforcing behavior of nanosilica. According to the above results, it is inferred that the silanol group of nanosilica cross-links with the am...

Developing green cement paste using binary and ternary cementitious blends of low pozzolanic sewage sludge ash and colloidal nanosilica (short-term properties)

This study investigates the effect of small dosages of nanosilica (0.5 and 1.5% of the total binder) on physical, mechanical, durability, and microstructural properties of green cement paste containing sewage sludge ash (SSA) with low pozzolanic activity. Experimental results revealed that hardened performances of cement pastes were reduced significantly by incorporating SSA particles at higher replacement ratios (> 10%), whereas mechanical and durability properties of cement paste specimens were improved by the addition of nanosilica both at early and moderate ages. According to the microstructural investigation, the activity of SSA particles in the presence of nanosilica can be improved.

Influence of steam curing and nano silica on hydration and microstructure characteristics of high volume fly ash cement system

In order to find a suitable way to improve the early strength of cement-high volume fly ash (CHVFA) system, nano silica (NS) was introduced. Two curing regimes with the same curing time was conducted: one is under standard curing (20 ± 2 °C, RH ≥ 95%) for 3 days, and the other is under steam curing (65 ± 2 °C, RH ≥ 95%) for 12 h and then standard curing for 60 h. The effect of NS and curing regimes on properties of CHVFA was systematically investigated. Pore structure, hydration products, and microstructure of interfacial transition zone (ITZ) were studied to reveal the mechanism behind the improvement in compressive strength. Results show that addition of NS can increase the strength of 3 days, regardless of the curing process. The reason for this increase is not only because of the accelerated hydrations of both cement and FA, but also due to the decrease in porosity and total pore volume as well as the improvement in the microstructure of ITZ. An interesting finding is that steaming curing can exert more efficient effect on increasing the strength in the presence of NS, which means that NS seems more effective to enhance the strength under steam curing, indicating an obvious synergistic effect between NS and steam curing in CHVFA system. Such results suggest effective way to improve the early strength of CHVFA paste, and the addition of NS can also promote the use of FA in precast concrete, with economic and environmental benefits.

An electrophoretic coating using a nanosilica modified polyacrylate resin

Polyacrylate resins were prepared by a copolymerization of acrylates and methacrylates, in the presence (or absence) of a reactive nanosilica (RN), and polyacrylate resins were also modified by a half-blocked toluene diisocyanate (TDI). The RN, was prepared by a sol-gel process using tetraethyl orthosilicate (TEOS) and functionalized with 3-(trimethoxysilyl) propyl methacrylate (MPS). The RN was determined to have an average particle diameter of around 10 nm. The resin was thus transformed into an emulsion and deposited on steel plate using an electrophoretic coating process. The deposited films were further cured in an oven, where the half-blocked TDI crosslinked to form networks. The presence of nanosilica in the deposited film enhances physical properties, such as abrasion resistance, impact resistance, and thermal stability.