Addition Of Silica Nanoparticles Research Articles

Hydrophilic and hydrophobic silica‐based nanocomposites of chemically recyclable thermoset

AbstractIn this study we evaluated the effect of the addition of hydrophilic and hydrophobic silica nanoparticles on the electrical properties of polyhexahydro‐s‐triazine (PHT), a new chemically recyclable thermoset produced from 2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane and paraformaldehyde. Chemical recycling as well as thermal and mechanical properties were also investigated. Regarding the electrical properties, electrical conductivity near 10−8 S m−1 at 100 Hz and dielectric constant close to 4.00 at 1 kHz were observed for neat PHT polymer. Better results for electrical properties were observed with the addition of hydrophobic silica nanoparticles. After the addition of the highest concentration (4.5 wt%) the dielectric constant increased about 8% at 1 kHz. Concerning the thermal properties, PHT polymer exhibited a glass transition temperature (Tg) of 185 °C. The addition of hydrophilic or hydrophobic nanoparticles into the neat matrix did not lead to significant variations of thermal properties, but Tg values were decreased compared to the neat resin. Additionally, for mechanical properties, values of reduced modulus (4.58 GPa) and nanohardness (0.38 GPa) were observed. Besides, for all nanocomposites, there was an increase in the reduced modulus for all samples studied. Finally, the chemical recycling of both neat polymer and all nanocomposites after acid treatment was successfully characterized via NMR analysis. © 2021 Society of Industrial Chemistry.

Linear Assembly of Two-Patch Silica Nanoparticles and Control of Chain Length by Coassembly with Colloidal Chain Stoppers.

The self-assembly of patchy nanosized building blocks is an efficient strategy for producing highly organized materials. Herein we report the chaining of divalent silica nanoparticles with polystyrene patches dispersed in tetrahydrofuran triggered by lowering the solvent quality. We study the influence of the patch-to-particle size ratio and show that the nature of the added nonsolvent, for example, ethanol, water, or salty water, and its volume fraction should be carefully adjusted. We demonstrate that colloidal assembly initially obeys the kinetic model of step-growth polymerization and that beyond a certain length, the chains have the possibility to cyclize. We also show that the length of the chains can be controlled by the addition of one-patch silica nanoparticles, which act as colloidal analogues of chain stoppers.

Improvement of impact strength of novel intra-ply basalt/kevlar composite by addition of silica nanoparticles in comparison with basalt/kevlar composite using resin transfer mould process

The objective of this work was to enhance the impact strength of hybrid basalt/kevlar composite by the addition of 8% of silica nanoparticles. In this research work, a novel composite laminate was developed using hybrid composite fibers i.e basalt and kevlar with addition to silica nanoparticles. The influence of silica nanoparticles as filler material on the mechanical properties is studied. The two groups of materials are taken; they are the control group and the experimental group. In both groups, the basalt and kevlar fibers are used. The composite materials basalt/kevlar without addition of silica nanoparticles was considered as a control group. The composite materials basalt/kevlar with the addition of 8% silica nanoparticles was considered as an experimental group. From each group, twenty samples are taken for the study. The impact testing machine was used to conduct the impact test. The SPSS tools are used for statistical analysis. It was clearly shown that basalt and Kevlar fiber with filler exhibits an improvement of 20% increase in the impact strength when compared with basalt and Kevlar fiber without filler. The significance value of 0.029 which was less than 0.05. Within the scope of the study, the laminates with the addition of silica nanoparticles exhibit better impact strength compared with plain hybrid basalt and Kevlar composites that can be used as a replacement for automobile components and also aircraft fuselage.

The effect of particle reinforcements on chip formation and machining induced damage of modified epoxy carbon fibre reinforced polymers (CFRPs)

The epoxy matrix of a carbon fibre reinforced polymer (CFRP) was modified by addition of silica nanoparticles, rubber microparticles and a combination of both to determine the effect of particle reinforcements on chip formation and machining induced damage. The effect of epoxy particle reinforcement on the machinability of CFRPs was studied experimentally under orthogonal cutting conditions. The results show that the chip formation process is affected by the presence of particulate fillers regardless of individual ply fibre orientation. Subsequently, the measured cutting forces showed a representative behaviour for each particle type and concentration. Rubber modified samples showed the lowest subsurface damage and measured surface metrics, followed by silica and unmodified epoxy samples. This behaviour was linked with the toughening mechanism of rubber and silica particles, which was found to take place during the material removal process.

Effect of Strain Rate and Silica Filler Content on the Compressive Behavior of RTM6 Epoxy-Based Nanocomposites.

The aim of this paper is to investigate the effect of strain rate and filler content on the compressive behavior of the aeronautical grade RTM6 epoxy-based nanocomposites. Silica nanoparticles with different sizes, weight concentrations and surface functionalization were used as fillers. Dynamic mechanical analysis was used to study the glass transition temperature and storage modulus of the nanocomposites. Using quasi-static and split Hopkinson bar tests, strain rates of 0.001 s−1 to 1100 s−1 were imposed. Sample deformation was measured using stereo digital image correlation techniques. Results showed a significant increase in the compressive strength with increasing strain rate. The elastic modulus and Poisson’s ratio showed strain rate independency. The addition of silica nanoparticles marginally increased the glass transition temperature of the resin, and improved its storage and elastic moduli and peak yield strength for all filler concentrations. Increasing the weight percentage of the filler slightly improved the peak yield strength. Moreover, the filler’s size and surface functionalization did not affect the resin’s compressive behavior at different strain rates.

Electrospinning of ternary composite of PMMA-PEG-SiO2 nanoparticles: Comprehensive process optimization and electrospun properties

Electrospinning has been realized to be a promising method for creating nano-composite fibers due to its significant growth for producing innovative composites with advanced applications. In this method a polymeric solution subjected to an electrohydrodynamic process and slim charged liquid jet is formed inside a high potential electric field. The high voltage enables the production of continuously long fibers on a collector surface. Addition of different polymers and NPs to the one-component solution to modify the physicochemical characteristic and decorating the surface of electrospun fibers has proven to be challenging and imperative for many fields especially novel bioengineering and filtration applications. In this study, the effects of major parameters on the fabrication of electrospun fibers were extensively investigated. At the first step, formation of nanofibers on the surface of collector and optimization of process parameters were determined based on the mean diameter of resulting fibers, through SEM (Scanning Electron Microscopy) images. The optimum values for concentration, applied voltage, the distance between the tip of needle and collector, and flow rate determined to be 10 wt%, 12 kV, 20 cm, and 0.6 mL h−1, respectively. Afterwards, the hydrophilicity of fibers was modified by adding different poly (ethylene glycol) (PEG) concentrations (20, 30, and 40 wt%) to the polymeric solution. The contact angle analysis revealed that the poly (methyl methacrylate) (PMMA) and 30 wt% PEG fabricated fibrous mat exhibited a better wettability and 71.61% lower hydrophobicity compared to pure PMMA electrospun mats. In the next step, silica NPs (nanoparticles) were introduced to the polymeric solution of electrospinning in the form of an IPA (isopropanol)-based collide solution. The dispersed solution-based addition of silica NPs prevented the aggregation state of NPs in the nanofibers. The addition of silica nanoparticles also changed the thermal and mechanical properties of the ternary composite, which were analyzed in TGA (thermogravimetric analysis) and tensile tests. Noteworthy, the addition of 30% PEG and silica NPs increase 3 times the tensile strength and around 2 times elongation in comparison with pure PMMA electrospun mats. These results highlight that the hybrid composite leads to a promising new electrospun mat for filtration and bioengineering applications.

An Investigation of the Effect of the Addition of Hydrophobic Silica Nanoparticles on the Colloidal Stability of Inverse Emulsions

An Investigation of the Effect of the Addition of Hydrophobic Silica Nanoparticles on the Colloidal Stability of Inverse Emulsions

A Review on Synthesis, Properties, and Applications of Polylactic Acid/Silica Composites.

Polylactic acid (PLA)/silica composites as multifunctional high-performance materials have been extensively examined in the past few years by virtue of their outstanding properties relative to neat PLA. The fabrication methods, such as melt-mixing, sol–gel, and in situ polymerization, as well as the surface functionalization of silica, used to improve the dispersion of silica in the polymer matrix are outlined. The rheological, thermal, mechanical, and biodegradation properties of PLA/silica nanocomposites are highlighted. The potential applications arising from the addition of silica nanoparticles into the PLA matrix are also described. Finally, we believe that a better understanding of the role of silica additive with current improvement strategies in the dispersion of this additive in the polymer matrix is the key for successful utilization of PLA/silica nanocomposites and to maximize their fit with industrial applications needs.

Influence of the Addition of Silica Nanoparticles on the Compressive Strength of Cement Slurries under Elevated Temperature Condition

Drilling ever deeper, and thus in increasingly difficult conditions, is associated with restrictive requirements that must be met by cement slurries. This implies the need to use advanced, innovative measures that will significantly improve the performance parameters of the cement slurry and cement stone. Due to its unique properties, an admixture of nanosilica improves the properties of the cement stone and allows for appropriate zone insulation. The article presents the results of strength tests of cement stone samples with the addition of silica nanoparticles deposited in an environment of increased temperature of 90 °C. In all three cases of modification with an admixture of nanosilica (type 1, 2 and 3, concentration 0.5%, 1% and 5%), the cement stone shows an improvement in mechanical properties, which is manifested by an increase in compressive strength. The most homogeneous results of strength measurements are for cement slurries with an admixture of type 3 nanosilica (the highest average strength: 132–149% in relation to the base sample). They show the smallest stretch marks and deviations from the average. The highest average increase in strength is for the sample with the addition of 1% nanosilica (on average 124% in relation to the base sample). This amount causes the greatest increase in strength with no significant deterioration of rheological parameters.

Chitosan/Polyvinyl Alcohol/SiO2 Nanocomposite Films: Physicochemical and Structural Characterization

In the present study, the effects of the two ratios of polyvinyl alcohol /Chitosan (1:1 and 3:1) and nano-silicon dioxide (nano-SiO2) (0, 0.5, and 1%) on structural and physicochemical properties of PVA/Chitosan/ nano-SiO2 nanocomposite films were investigated. Our findings showed that the treatments' water solubility (WS) in the presence of nano-SiO2 and higher PVA content was decreased, and the lowest amount was in P3C1-1% (59%). The addition of silica nanoparticles decreased the water vapor permeability (WVP) of films, and the lowest amount of WVP was for treatment with a ratio of 1:1 of PVA/chitosan and 1% nano-SiO2 (P3C1-1%) which was 3.08× 10-10 g m s-1m-2 Pa. Tensile strength (Ts) value was achieved 35.86 MPa in higher PVA content and 1% of nano-SiO2 (P3C1-1%) which was the highest. However, the light transmission value of all treatments did not differ greatly. According to the FTIR results, the appropriate interaction between both polymers and nano-SiO2 was observed in the concentration of 1% nano-SiO2 in P1C1. Eventually, significant improvement of structural and physicochemical properties of the films could achieve in higher PVA content and concentration of 1% of nano-SiO2. Based on these results, these nanocomposite films could be considered suitable for the packaging sector and preserve food quality.

Enhancing Thermo-Mechanical Properties of Epoxy Composites Using Fumed Silica with Different Surface Treatment.

The objectives of this study are to improve the thermal and mechanical properties of epoxy/fumed silica composite with different surface treatments of fumed silica. The addition of silica nanoparticles improved the thermal stability of the composite and slowed down the pyrolysis process. The crosslinking density and Tg of the epoxy/fumed silica composites increased because of the interfacial interaction between the PDMS-treated fumed silica particles and the epoxy matrix. The flexural strength of the epoxy nanocomposite was very high even at a low silica content because of the strong interactions between the PDMS-treated fillers and the epoxy matrix. These strong interfacial interactions originate from the attractive forces between the polymer and the filler. Therefore, the polymer nanocomposite containing the PDMS-treated fumed silica is shown to be sufficiently commercially promising.

Dehydration of Natural Gas Using Polyether Sulfone (PES) Membrane and Its Nanocomposite with Silica Particles and Nitrogen Sweeping Gas

Natural gas must be dehydratedbefore being sent to the distribution network to control corrosion and prevent the formation of solid hydrates. Membrane technology is a viable alternative to conventional glycol absorbents and adsorbent solids. This study was performed to evaluate the dehydration of crude natural gas by membrane separation process. Various operating conditions such as the effect of silica nanoparticles, pressure and sweeping gas on the removal of water vapor dissolved in natural gas were investigated using PES membrane and its nanocomposite. PES membranes and their nanocomposites with silica was made by solution mixing method in solvent dimethyl formamide. The properties of silica nanoparticles and fabricated nanocomposite membranes were evaluated by Fourier transfer spectroscopy and scanning electron microscopy. The dehydration rate was from natural gas in the pressure range of 2 to 10 bar and temperature of 30 °C in the presence of nitrogen sweeping gas. The addition of silica nanoparticles to the PolyetherSulfonemembrane significantly reduced the moisture content of natural gas. Also, with increasing feed pressure, the amount of water permeation from the membrane improved. The use of nitrogen sweeping gas reduced the amount of water in natural gas in pure Polyether Sulfone membranes by more than 80% and in nanocomposite membranes by more than 100%.

Synergistic toughening of poly(lactic acid)/poly(ethylene vinyl acetate) (PLA/EVA) by dynamic vulcanization and presence of hydrophobic nanoparticles

AbstractThe presented research reports a successful preparation of a super toughened poly(lactic acid)/poly(ethylene vinyl acetate) (PLA/EVA) blend using simultaneous dicumyl peroxide (DCP)‐induced dynamic vulcanization and addition of hydrophobic spherical silica nanoparticles (NPs). The torque evolution during melt mixing of the samples was assessed to track the dynamic vulcanization process. NPs were localized mainly in the EVA droplets and at the interface where a layer of particles was formed with a small amount dispersed in the PLA matrix. The incorporation of NPs or DCP induced compatibilization, causing a drastic decline in the size of EVA droplets in addition to improving the interfacial adhesion. On the other hand, simultaneous dynamic vulcanization and NPs incorporation synergistically affected the compatibilization of EVA and PLA phases. Differential scanning calorimetry (DSC) was employed to analyze the thermal transition and crystallization behavior of the samples. Simultaneous incorporation of silica nanoparticles and DCP at an optimum content significantly improved the tensile toughness, elongation at break, and impact strength, giving rise to super toughened PLA/EVA blend. The elongation at break and impact strength of the dynamically vulcanized PLA/EVA blend containing 5% nanosilica showed an increase from 7% to 175% and 5.1 to more than 77 kJ/m2, respectively as compared to the neat sample. Based on SEM analysis of the fractured surface of the tensile samples, cavitation in combination with intensive shear yielding of the matrix were dominating toughening mechanisms. Finally, the effect of DCP and NPs on the microstructural properties of the sample was investigated through rheological evaluations.

Investigation on the partial discharge characteristics of eco‐friendly nanofluid insulation of corn oil nanofluid

The suitability of corn oil nanofluid as an insulation material is studied herein by analysing the partial discharge characteristics. Experiments are conducted on nano-silica modified corn oil at 0.01, 0.05, and 0.1 wt.% mass fractions. Electrode configurations are used to generate partial discharge (PD) sources such as corona discharge, internal discharge, and surface discharge. Partial discharge inception voltage dependency on electrode geometry is studied. Phase-resolved partial discharge analysis (PRPD) at various test conditions is done to understand the influence of live element geometry that causes PD in real-time operations, Weibull statistical analysis of PD parameters like scale parameter, shape parameter, skewness, and repetition rate is evaluated to understand the influence of nanofiller mass fraction in corn oil. The results illustrate that the addition of silica nanoparticles to corn oil has a significant influence on PD characteristics. The PRPD pattern analysis reveals information about the PD dependency on electrode configuration of the test condition. The addition of nanofillers in optimal concentrations without agglomeration can influence the PD characteristics to a certain degree. The test results may be inferred to suggest corn oil-based silica nanofluids as an alternative biodegradable liquid insulation.

Prediction of surface tension of solution in the presence of hydrophilic silica nanoparticle and anionic surfactant by ATR-FTIR spectroscopy and chemometric methods

In the current research, an analytical method was proposed for the quantitative determination of surface tension of anionic surfactant solutions in the presence of hydrophilic silica nanoparticles using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy and chemometric methods. The surface tension behavior of anionic surfactant solutions considerably changes by the addition of silica nanoparticles with different particle size. The spectral data of solutions were used for prediction of surface tension using two calibration methods based on support vector machine regression (SVM-R) as a non-linear algorithm and partial least squares regression (PLS-R) as a linear algorithm. For preprocessing of data, baseline correction and standard normal variate (SNV) were also applied. Root mean square error of prediction (RMSEP) in SVM-R and PLS-R methods were 4.203 and 4.507, respectively. Considering the complexity of the samples, the SVM-R model was found to be reliable. The proposed method is fast and easy for measurement of the surface tension of surfactant solutions without any sample preparation step in chemical enhanced oil recovery (C-EOR).

Experimental Study on Engineering Properties and Microstructure of Expansive Soils Treated by Lime Containing Silica Nanoparticles Under Various Temperatures

In this study, improvement rate of engineering properties of expansive soils caused by the effect of varying curing temperature together with the addition of Silica Nanoparticles on lime was evaluated utilizing a series of macro and micro-structural tests. Based on the results, as the temperature decreases (especially temperatures below 20 °C with storage duration shorter than 28 days), pozzolanic activities as well as growth process of cementitious mixtures (e.g. CSH and CAH Nanostructures), is disrupted and after the addition of lime, the improvement process will be majorly affected by short-term reactions (Cation-exchange capacity and increase in Osmotic pressure). Under such circumstances, it was found that an increase in the content of the mentioned additives can just control the expandability and the other geotechnical characteristics such as bearing capacity and settlement potential are negligibly improved. On the other hand, the results indicate that when the mixture of lime-silica nanoparticles (LNS) is added, undesirable effect of temperature loss on the engineering parameters is leveled down and unlike the limitations of lime performance, the compressive strength of improved specimens follows an increasing trend in proportion to the rate of increase in the additives content. Based on the X-ray diffractions as well as SEM images, the reason behind less susceptibility of specimens containing LNS to temperature and storage duration and consequently, a better behavior in comparison with those including just lime, arose from a greater number and faster process of pozzolanic reactions and compaction of the mixture’s structure. Conclusively, application of LNS (especially in cold weather and short curing duration) intensifies the lime’s effect and in addition, reduces the consumption of additives by 50%.

Nano-silica reinforced epoxy resin/nano-rubber composite material with a balance of stiffness and toughness

In the electronics and aerospace industries, epoxy resins are generally regarded as economical and efficient adhesives and have a high status. However, epoxy resins are highly crosslinked polymers and are very brittle adhesives where they are prone to fast crack propagation under dynamic loads. Therefore, it is very necessary to enhance the toughness of epoxy resin adhesives. Nano-rubber has been proved to be an important toughening agent for epoxy resin, which can significantly improve the fracture toughness of epoxy resin. However, increasing the toughness of epoxy resin by adding nanomaterials is often accompanied by decreasing the strength and stiffness of resin. Therefore, in this work, rigid nano-silica particles were added to improve the rigidity and tensile strength reduction caused by the addition of rubber particles. And further increase the toughness of the epoxy resin to obtain an epoxy adhesive with balanced stiffness-toughness. As a result, it can be found that the addition of silica particles can significantly improve the decrease in stiffness caused by the addition of rubber particles. For example, Young’s modulus and tensile strength are increased by 28%, and 23%, respectively, with 4% silica is added based on rubber particles. Through the single lap shear experiment, it is found that the shear strength of the epoxy/RnP/silica composite adhesive has increased, which further proves that the addition of nano-silica particles can increase the stiffness of the epoxy composite. The dynamic mechanical analysis experiment found that after adding nano-silica particles, the storage modulus of epoxy composites increased, which also shows that adding nano-silica particles can improve the stiffness of epoxy composites. Scanning electron microscopy analysis was performed to study the reinforcement mechanism of epoxy/RnP/silica composite materials. The thermal stability of epoxy composites was characterized by Dynamic mechanical analysis and thermogravimetric analysis.

Chip formation mechanism during orthogonal cutting of rubber microparticles and silica nanoparticles modified epoxy polymers

The addition of well-dispersed nanoparticles can significantly increase the mechanical properties and toughness of epoxy polymers. In this study, an epoxy resin was modified by addition of silica nanoparticles, (CTBN) rubber microparticles and a combination of both. An in-situ orthogonal cutting rig combined with high magnification and high-speed imaging system was used to determine the effects on the chip formation mechanism and machining induced damage to the material. This study indicates that chip formation in silica-modified epoxy is governed by a fracture process with large cracks both at the machined surface level and subsurface within the chip formation zone. The presence of rubber enables larger plastic deformation within the epoxy-modified polymer as the toughening mechanism of the rubber deflects the generated cracks within the primary deformation zone. The magnitude of machining induced damage was found to be lower for rubber microparticles and was correlated with a rubber toughening mechanism observed during cutting. The higher magnitude of machining induced damage of silica-modified epoxy was linked to the material’s poor resistance to crack initiation and growth. These findings of the effect of rubber microparticles and silica nanoparticles on chip formation process will give engineers a greater ability to create a trade-off between filler properties vs material properties vs machining induced damage during Design for Manufacturing (DFM) stages of a product design.

Ultra-stretchable, self-adhesive, transparent, and ionic conductive organohydrogel for flexible sensor

Conductive hydrogels are an ideal bio-integrated soft material and show great potential in soft sensors. However, it remains a great challenge to develop an integrated conductive gel combining excellent environmental stability and mechanical properties. Herein, we synthesize a transparent, self-adhesive conductive organohydrogel with excellent environmental stability and UV-blocking performance by constructing multiple cross-links between tannic acid, polyacrylamide, and polyvinyl alcohol. The addition of vinyl hybrid silica nanoparticles can promote dynamic cross-linking of polymer networks and endow organohydrogels with superior mechanical performance (>1800%, 320 kPa). Concurrently, the binary solvent system comprising water and ethylene glycol enables organohydrogels to accommodate different application environments (from −40 °C to 40 °C). Notably, with the incorporation of tannic acid, organohydrogels exhibit lasting and repeatable adhesion (80 kPa), as well as good UV-blocking (>90%). Furthermore, these conductive organohydrogels with great strain sensitivity were used as strain sensors to monitor and distinguish large movements (soft robot movements) and subtle human movements (smiling and electrocardiograph signal) at different temperatures. The conductive organohydrogels have great potential in healthcare monitoring and smart wearable soft electronic devices.

Preparation of poly‐d,l‐lactide based nanocomposites with polymer‐grafted silica by melt blending: Study of molecular, morphological, and mechanical properties

AbstractPolylactide was first designed for the pharmaceutical and medical fields. Unfortunately, polylactide, especially poly‐d,l‐lactide (PDLLA), presents too low mechanical properties for a wide range of applications. The addition of silica nanoparticles should reinforce the mechanical strength of PDLLA. In order to improve silica/polymer interactions, this study focused on the preparation of polymer chain grafted silica using two grafting methods. The first strategy relied upon the ring opening polymerization ofd,l‐lactide on initiating silica surface (ie, “grafting from”). The second approach considered a sol‐gel synthesis process in presence of Si‐OR terminated polylactide chains to promote grafting of these chains on new silica particles (ie, “grafting to” method). Only “grafting from” silica successfully led to a nanoscale dispersion into the polyester matrix for silica content up to 5 wt%. A 3 wt% content of this silica allowed improving Young modulus of 106.0% and ultimate tensile stress of 63.7% compared to the PDLLA control.