SiO2 Particles Research Articles

Controllable preparation of wollastonite-based composite coating for highly-efficient passive daytime radiative cooling in building

The building cooling has aroused widespread attention due to its significant contribution to both global warming and energy usage. To combat global warming and reduce energy consumption, an environmentally friendly beneficial alternative to electric cooling for buildings is passive daytime radiative cooling (PDRC). However, many of the reported radiative coolers still suffer from the challenge of complex preparation processes and high costs, making it difficult to scale up for building applications. Herein, the utilization of abundant and low-cost natural resources (i.e., cellulosic biomass and minerals) is strategized to produce radiative cooling material and incorporate this material into building cooling systems to boost global carbon neutrality. Guided by this concept, a hydrophobic SiO2/EC composite (HSEC) coating is designed by embedding nano-sized wollastonite-based SiO2 particles into porous ethyl cellulose (EC) polymer, and subsequently through polydimethylsiloxane (PDMS) dispersion spray treatment. Benefiting from the sufficient scattering by the nano-SiO2 particles and randomly dispersed light-scattering air voids, the resulting cooling coating shows a high solar reflectivity of 95.1 %. More importantly, the molecular vibration of the chemical in HSEC coating results in a high atmospheric window emissivity of 92.5 %. In the field test, the HSEC coating remained approximately 4.2 °C below the ambient temperature under intense solar irradiation of 412.5 W⋅m−2. This work not only offers a promising strategy for realizing the high-value utilization of wollastonite resources in building materials, but also provides a controllable approach for large-scale preparation of highly efficient radiative cooling materials to alleviate building cooling demands.

Baffle effect of exposed WC particles in the clearance on slurry erosion behavior of cemented carbide surface

Erosion damage of clearance fits is the major factor for the failure of metal-to-metal screw motors. In this study, the slurry erosion behavior of the WC-based laser cladding layer was investigated. It aimed to explore the effect of SiO2 particle concentration on the laser cladding layer. The experimental results indicate that the WC-based laser cladding layer exhibits excellent erosion resistance across various particle concentration environments. The presence of the 'baffle effect' resulted in the cladding layer demonstrating enhanced erosion resistance, particularly at high particle concentrations. The 'baffle effect' refers to exposed WC particles hindering the movement of SiO2 particles. As SiO2 particles continuously impact the clearance material surface, much of the matrix on the cladding surface is removed. The presence of remaining WC particles on the clearance material can impede the impact of particles in the slurry. The current results aim to offer experimental support for future investigations of surface strengthening methods for metal-to-metal screw motors.

Techno-Economic analysis of an efficient anthocyanin extraction process from grape pomace using eutectic solvents ─ A critical panorama regarding drying techniques and reusability of solvents

A techno-economic analysis of a novel eutectic solvent-based platform useful to recover anthocyanins from grape pomace was performed. The study addressed the economic impact of conventional drying methods and explored the economic implications of purification strategies to separate the extract from the eutectic solvent. This was exemplified by employing solid-phase extraction (SPE) with C18-based adsorbent material. An alternative low-energy demanding approach using SiO2 particles was also assessed for profitability as a freeze-drying replacement strategy. The results highlighted challenges in the economic feasibility of eutectic solvent reusability when conventional SPE is applied, highlighting the need to obtain new and inexpensive bio-based adsorbents. Moreover, it was uncovered that the SiO2-based drying strategy presents itself as a financially viable alternative, effectively addressing the elevated energy requirements associated with conventional drying methods. The findings highlight the potential of alternative solvents-based processes, particularly towards challenges related to the circularity of raw materials.

HCl removal from cement bypass flue gas at medium-high temperatures using cement bypass dust: Performance, mechanism, and adsorption kinetics

The use of alternative fuels is a growing trend in the cement industry, and it may lead to issues with HCl emissions. This study investigated the HCl removal performance of cement bypass dust (CBPD) at medium-high temperatures (500–700℃). This is not only of great significance for controlling HCl emissions from cement kilns but also alleviates the disposal pressure of this industrial solid waste. The results show that HCl adsorption capacity increased first and then decreased with increasing temperature, reaching a maximum of 676 mg/g at 600°C. The HCl concentrations significantly influenced the reaction rate, yet its impact on the uptake chlorine capacity is comparatively minimal. CBPD without size separation showed the best dechlorination performance and highest final chlorine capacity compared with CBPD of size 0–48 μm and 48–75 μm. Blending inert SiO2 particles into CBPD can greatly increase the breakthrough time. The longest breakthrough time is 7580 seconds, approximately 35 times that of CBPD without dispersion. CaO is the primary substance in CBPD to remove HCl, and the reaction produces CaCl2 and its hydrate. A shrinking core model was used to analyse the experimental data, suggesting a combination control of the chemical reaction and the product diffusion.

Cold spray deposition of high density polyethylene composite powders

In this paper, we investigate the use of the cold spray additive manufacturing technique to deposit micron-sized composite particles of high-density polyethylene (HDPE) compounded with either micron or nanometer sized particles of silicon dioxide (SiO2) or copper (Cu). In this study, the mass fraction of the SiO2 and copper particles added into the final composite powders was varied between 0.5 % and 9.1 % and the deposition efficiency of each composite powder was measured. Deposition of the composite powders onto an HDPE substrate was successful even at the highest particle loadings tested. In each case, an optimal mass fraction of silicon dioxide or copper particles was observed with a maximum value of deposition efficiency larger than that of the pure HDPE. For the silicon dioxide composite powders, the deposition efficiency nearly doubled compared to the pure HDPE powders. The improvement of deposition efficiency at moderate particle loadings is likely due to the increase in the impact kinetic energy of the particles resulting from the increase in the density of the composite powders. While the decrease in deposition efficiency at high particle loadings is likely the result of the increased coverage of the silicon dioxide and copper particles on the surface of the HDPE powders limiting the interaction between the HDPE of the composite powder with the HDPE substrate. SEM images show that it is possible to create a smooth, dense, and uniform thin-film polymer composite coating using cold spray.

Study on the mechanism of interaction between cations and the surface of nano-SiO2 particle in the salt solution by using molecular dynamics simulation

Nano-SiO2 solution has great potential for application in the field of oil and gas exploration and development. However, its application is restricted due to the aggregation of nano-SiO2 in stratum water. This paper studies the process of interaction between nano-SiO2 particles and salt solutions by using the molecular dynamics simulation experiments, including the characteristics of transportation and diffusion of cations around the nano SiO2, the effect of cations on the recombination and destruction of hydrogen bonds, the interaction energy between cations and nano SiO2. The main results are as follows. During the transportation and diffusion of cations in the solution, the hydrogen bonds of water molecules are broken, so that the hydrogen bonds can be rearranged, and a stable solvated layer can be formed. In the solvated layer, the repulsive force of solvation can prevent the charge exchange between cation and the charged surface of nano SiO2 particle. Compared with the monovalent salt solution, more divalent cations can break through the solvation layer to generate the charge exchange on the surface of nano-SiO2 particle. More divalent cations can conduct small amplitude oscillation movement near the surface of nano-SiO2 particle due to the strong electrostatic effect. When the concentration of salt solution is increased (3000 mg/L → 7000 mg/L) and the valence of cations is increased (monovalent → bivalent), the hydrogen bond is easier to break through the solvation layer to gather on the surface of nano SiO2 particles, which is unfavorable to the stability of nano SiO2 particles. When the cations transport to the position of 7 Å away from the surface of nano-SiO2 particles, the short-range force (including hydrogen bond force, van der Waals force, and electrostatic force) begins to affect the movement of cations. When the cations transport to the position of 2 ∼ 3 Å away from the surface of nano-SiO2 particles, the charge exchange occurs between cations and the surface of nano SiO2 particle, so that the local energy is increased and the cation continues to oscillate. In summary, with the increasing of concentration of salt solution and the valence state, more cations can break through the solvation layer to be adsorbed on the surface of nano SiO2 particle, showing that the ability of transportation and diffusion of cations is weakened, the interaction energy between nano SiO2 particle and salt solution molecules is enhanced. The electrostatic force is the main force to destroy the stability of nano SiO2 particle. The conclusions can provide a certain theoretical basis for the efficient application of nano-SiO2 materials in the field of oil and gas exploration and development and other interrelated industry.

Structural Color Materials with Color Mixing Effect Using Noble Metal‐Free Plasmonic Particles in SiO2–ZrN System

AbstractStructurally colored materials with a color mixing effect are developed using SiO2–ZrN core–shell particles, where ZrN nanoparticles used as shells exhibited localized surface plasmon resonances (LSPRs). ZrN nanoparticles (10–30 nm) are attached to monodispersed SiO2 particles by modifying SiO2 particles with polymers. The attached ZrN nanoparticles exhibited a plasmon resonance absorption band at 700 nm. These SiO2–ZrN core–shell particles have a highly monodisperse particle size and assemble into a particle‐stacked film with Bragg diffraction light in the visible spectrum. The particle‐stacked film of the SiO2–ZrN core–shell particles exhibited the maximum reflection depending on the particle size of the SiO2 core. The ratio of the reflection intensity in the long‐wavelength region corresponding to the ZrN absorption to that in the short‐wavelength region of the particle‐stacked film containing the ZrN shell is less than that of the ratio in only SiO2 particle‐stacked film. The results reveal that these particle‐stacked films exhibit a “color mixing effect” that combines specific wavelength absorption through plasmon resonance and specific wavelength diffraction owing to the periodic structure without using precious metals.

Critical parameters to standardize the size and concentration determination of nanomaterials by nanoparticle tracking analysis

The size and concentration are critical for the diagnostic and therapeutic applications of nanomaterials but the accurate measurement remains challenging. Nanoparticle tracking analysis (NTA) is widely used for size and concentration determination. However, highly repeatable standard operating procedures (SOPs) are absent. We adopted the “search-evaluate-test” strategy to standardize the measurement by searching the critical parameters. The particles per frame are linearly proportional to the sample concentration and the measured results are more accurate and repeatable when the concentration is 108-109 particles/ml. The optimal detection threshold is around 5. The optimal camera level is such that it allows clear observation of particles without diffractive rings and overexposure. The optimal speed is ≤ 50 in AU and ∼ 10 μl/min in flow rate. We then evaluated the protocol using polydisperse polystyrene particles and we found that NTA could discriminate particles in bimodal mixtures with high size resolution but the performance on multimodal mixtures is not as good as that of resistive pulse sensing (RPS). We further analyzed the polystyrene particles, SiO2 particles, and biological samples by NTA following the SOPs. The size and concentration measured by NTA differentially varies to those determined by RPS and transmission electron microscopy.

Kinetic Regularities of the Synthesis of Silica Nanoparticles by Heterogeneous Hydrolysis of Tetraethoxysilane Using L-Arginine as a Catalyst

Abstract The kinetics of the synthesis of silica nanoparticles (<50 nm) has been studied under the conditions of heterogeneous hydrolysis of tetraethoxysilane (TEOS) using L-arginine as an alkaline catalyst. The rates of silica formation have been determined in a temperature range of 10–95°C at catalyst concentrations of 6–150 mM. It has been shown that the activation energy of the process depends on catalyst concentration and varies in a range of 21.5–13.9 kJ/mol, while decreasing linearly with increasing concentration of L-arginine in the system. The criterion of maintaining the monodispersity has been estimated for SiO2 particles being grown “onto seeds.” The density of submicron-sized silica particles has been experimentally determined as depending on the annealing temperature. Within a temperature range of 200–1000°C, the particle density varies from 2.04 to 2.20 g/cm3.

Enhanced solid particle erosion resistance of nanocrystalline Ni-W coatings through multilayer approach

Electrodeposited nanocrystalline Ni-W alloy coatings are projected as potential alternatives for hard chrome (HCr) coatings owing to their comparable hardness and superior corrosion resistance. However, the limited strain hardening ability of the nanocrystalline Ni-W coatings manifests in their poor resistance towards solid particle erosion involving a high strain-rate (>103 s−1) deformation. In the present study, a novel microstructural engineering strategy has been implemented to enhance the strain hardening ability of the nanocrystalline Ni-W coatings without compromising on their strength/hardness. Ni-W multilayer coatings composed of alternatively stacked soft (2.6 GPa) and hard (8.5 GPa) Ni-W layers were developed using the pulse reverse electrodeposition technique. Further, to investigate the effect of individual layer thickness (λ), multilayer coatings with different λ were deposited. Solid particle erosion testing using the angular SiO2 particles showed that the multilayer coatings (irrespective of λ) exhibit superior erosion resistance compared to the homogeneous nanocrystalline Ni-15W at both oblique (θ = 30°) and normal (θ = 90°) impact conditions. The post-erosion microstructural analysis of the multilayer coatings revealed that the hard Ni-W layers undergo uniform strain (ε > 50 %) without cracking due to the constrained co-deformation imposed by the surrounding soft Ni-W layers. Therefore, the enhanced erosion resistance of the multilayer coatings is attributed to the effective dissipation of impact energy through co-deformation of the individual hard and soft Ni-W layers.

Structure and Properties of Epoxy Resin/Graphene Oxide Composites Prepared from Silicon Dioxide-Modified Graphene Oxide.

In this study, graphene oxide (GO) was modified via electrostatic interactions and chemical grafting by silica (SiO2), and two SiO2@GO hybrids (GO-A and GO-B, respectively) with different structures were obtained and carefully characterized. Results confirmed the successful grafting of SiO2 onto the GO surface using both strategies. The distribution of SiO2 particles on the surface of GO-A was denser and more agglomerated, while it was more uniform on the surface of GO-B. Then, epoxy resin (EP)/GO composites were prepared. The curing mechanism of EP/GO composites was studied by differential scanning calorimetry and in situ infrared spectra spectroscopy. Results of tensile tests, hardness tests, dynamic mechanical analysis, and dielectric measurement revealed that EP/GO-B exhibited the highest tensile properties, with a tensile strength of 79 MPa, a 43% increase compared to raw EP. Furthermore, the addition of fillers improved the hardness of EP, and EP/GO-B showed the highest energy storage modulus of 1900 MPa. The inclusion of SiO2@GO hybrid fillers enhanced the dielectric constant, volume resistivity, and breakdown voltage of EP/GO composites. Among these, EP/GO-B displayed the lowest dielectric loss, relatively good insulation, and relatively high volume resistivity and breakdown voltage. A related mechanism was proposed.

Digital light processing printing of porous ceramics using interparticle photo-cross-linkable Pickering emulsions

Digital light processing (DLP) printing using photo-curable Pickering emulsion is a promising route to fabricate porous ceramics having on-demand structures. However, the long duration for debinding/sintering due to the large organic contents remained in the photo-cured bodies and the insufficient long-term stability of the emulsions needs to be solved toward efficient manufacturing. Herein, a new interparticle photo-cross-linkable Pickering emulsion having improved stability, which can be photo-cured using reduced amounts of monomers, were designed for the rapid production of porous ceramics using DLP printing. The Pickering emulsion was obtained by mixing isopropyl myristate into a dimethyl sulfoxide (DMSO) aqueous suspension of SiO2 particles with pre-dissolved polyethylene glycol diacrylate (PEGDA) and a photo-radical initiator. Further, functionalized polyethyleneimine (PEI) was designed to ensure the dispersion of SiO2 particles and formation of a Pickering emulsion. The photo-irradiation of the designed Pickering emulsion resulted in the successful photo-curing by the radical polymerization of PEGDA, followed by a Michael addition reaction between the reactive amine of PEI and acryloyl groups of PEGDA. The improved stability of the emulsion over time and reduced amounts of monomer facilitated the application of the designed emulsion to DLP printing, followed by a rapid firing process without any structural collapse.

Designing Urchin-Like S/SiO2 with Regulated Pores Toward Ultra-Fast Room Temperature Sodium-Sulfur Battery.

Captured by high theoretical capacity and low-cost, Sodium-Sulfur (Na-S) batteries have been deemed as promising energy-storage systems. However, their electrochemical properties, containing both cycling and rate properties, still suffer from the notorious "shuttle effect" of polysulfide. Herein, through the effective regulation of pore sizes, a series of S/SiO2 cathode materials are obtained. Benefitting from the abundant pore channels of SiO2 particles, the sulfur loading is as high as 76.3%. Importantly, a suitable pore size can lead to adequate reaction and rapid diffusion behaviors, resulting in excellent electrochemical performances. Specifically, at 2.0Ag-1, the initial capacity of the as-optimized sample can be up to 1370.6mAhg-1. Surprisingly, even after 1050 cycles, it could achieve a high reversible capacity of 1280.8mAhg-1 with an attenuation rate of 0.089%. At 5.0Ag-1, after 500 cycles, the capacity can still remain ≈ 1132.6mAhg-1 (capacity retention rate, 97.5%). Given this, the work is anticipated to offer an effective strategy for advanced electrodes for Na-S batteries.

Structure and Characteristics of Opal - Bi<sub>12</sub>GeO<sub>20</sub> and Opal - NaBi(MoO<sub>4</sub>)<sub>2</sub> Nanocrystalline Composites

In this work we investigate and analyze phase composition and structure parameters of the nanocomposites obtained by the melt-based impregnation of porous opal matrices with dielectrics prospective for optoelectronics applications Bi12GeO20 and NaBi (MoO4)2. The embedded material is formed inside opal pores as nanocrystals with an average linear size not exceeding 50 nm and modified lattice parameters. In the case of impregnating opals with Bi12GeO20, new additional compounds are produced and transformation of opal matrix from amorphous to crystalline state is observed. These effects are discussed in the framework of the interaction of bismuth cations with the surface of the 285 nm SiO2 particles that compose opal matrix. No stoichiometry deviations and new phases are detected in “opal-NaBi (MoO4)2” composite.

Preparation of TiO2–SiO2–CaCO3 composite opacifier by hydrophobic agglomeration and mechanism of inhibiting glaze yellowing

This study investigates the preparation of TiO2–SiO2–CaCO3 composite opacifier (Ti–Si–Ca) and its application in sanitary ceramic glazes. This approach involved hydrophobic agglomeration through surface-induced hydrophobic modification of TiO2, SiO2 and CaCO3 particles, along with the interactions between the hydrophobic carbon chains of modifiers. The Ti–Si–Ca formed a uniform coating with well-dispersed TiO2 and SiO2 particles on the CaCO3 surface and strong bonds formed among TiO2, SiO2 and CaCO3 through interpenetration of the organic carbon chains on the surface. The Ti–Si–Ca was added to the basic glazes of sanitary ceramics at a proportion of 15.5 % and fired at 1125 °C for 4 h. The resulting white ceramic glazes had chromaticity values of L*, a*, and b* at 93.76, −0.73, and 3.89, respectively, demonstrating superior glaze opacity and whiteness compared to glazes made with a ZrSiO4 opacifier (L* 90.30, b* 4.50). Glass and titanite phase make up the majority of the Ti–Si–Ca ceramic glazing layer of, with titanite serving as the opacified phase. Elimination of organic groups in Ti–Si–Ca during glaze firing formed interfacial chemical bonds among TiO2, SiO2 and CaCO3, which facilitated the synthesis of titanite from the three components at high temperatures. The Ti–Si–Ca was a highly opaque glaze without yellowing because the organic groups of Ti–Si–Ca were removed and interfacial chemical bonds formed among the TiO2, SiO2 and CaCO3 in the low-temperature stage of glaze firing. This transformed the three phases into titanite at high temperature and eliminated free TiO2. The formation of rutile TiO2, which has a yellow hue, at high temperatures was inhibited. This study provides a novel approach for low-energy preparation of TiO2–SiO2–CaCO3 composite opacifiers and addresses the challenge of replacing ZrSiO4 with TiO2 in ceramic opacifiers.

Investigating and characterizing electrical properties of polypyrrole/SiO2/FePS3 nanocomposite

AbstractNovel nanocomposites of polypyrrole (PPy) embedded in silica (SiO2) and iron phosphorus trisulphide (FePS3) nanoparticles have been fabricated. The nanocomposite's dielectric characteristics have been examined in relation to temperature ranges of 25–200°C and frequency ranges of 0.1–7 MHz. Fourier‐transform infrared spectroscopy (FTIR), x‐ray diffraction (XRD), scanning electron microscopy (SEM–EDX), transmission electron microscope (TEM), and dielectric measurements have all been used to evaluate the prepared nanocomposite. The monoclinic crystal structure of the prepared FePS3 and PPy/SiO2/FePS3 nanocomposite is confirmed by XRD, EDX, and TEM studies. The FePS3 is perfectly layered structure in the SEM image, and FePS3 and SiO2 particles are well intercalated, creating novel nanocomposites of two nanoparticle phases that served as a union network during the polymerization process. The IR spectrum shows that PPy is a dopant in the interlayer area of FePS3. The splitting major peak (570 cm−1) of FePS3 is visible at around 640 and 560 cm−1. The high AC conductivity values indicated that the combination of FePS3/SiO2 nano‐matrix contains PPy at high packing densities and confirming the semiconducting properties of the nanocomposite to be used in several electronic applications.

Intelligent responsive self-assembled micro-nanocapsules: Used to delay gel gelation time

In the application of polymer gels to profile control and water shutoff, the gelation time will directly determine whether the gel can “go further” in the formation, but the most of the methods for delaying gel gelation time are complicated or have low responsiveness. There is an urgent need for an effective method for delaying gel gelation time with intelligent response. Inspired by the slow-release effect of drug capsules, this paper uses the self-assembly effect of gas-phase hydrophobic SiO2 in aqueous solution as a capsule to prepare an intelligent responsive self-assembled micro-nanocapsules. The capsule slowly releases the cross-linking agent under the stimulation of external conditions such as temperature and pH value, thus delaying gel gelation time. When the pH value is 2 and the concentration of gas-phase hydrophobic SiO2 particles is 10%, the gelation time of the capsule gel system at 30, 60, 90, and 120 °C is 12.5, 13.2, 15.2, and 21.1 times longer than that of the gel system without containing capsule, respectively. Compared with other methods, the yield stress of the gel without containing capsules was 78 Pa, and the yield stress after the addition of capsules was 322 Pa. The intelligent responsive self-assembled micro-nanocapsules prepared by gas-phase hydrophobic silica nanoparticles can not only delay the gel gelation time, but also increase the gel strength. The slow release of cross-linking agent from capsule provides an effective method for prolongating the gelation time of polymer gels.

The Effect of SiO2 Particle Size on Crystallization Behavior and Space Charge Properties for SiO2/MMT/LDPE Composites.

The matrix material used in this paper was low-density polyethene (LDPE), and the added particles selected were silicon oxide (SiO2) particles and montmorillonite (MMT) particles. The sizes of the SiO2 particles were 1 µm, 30 nm, and 100 nm, respectively; three kinds of SiO2/MMT/LDPE multi-component composites were prepared based on MMT/LDPE composites doped with MMT particles. The effect of the SiO2 particle size on the crystallization behavior and space charge properties of SiO2/MMT/LDPE composites was studied. The crystalline behaviors and crystallinity of the materials were analyzed. At the same time, the changes in the relative dielectric constant εr and loss factor tanδ for each material with the influence of frequency were studied, and the space charge accumulation, residual characteristics, and apparent charge mobility of each material were explored. The results show that the smaller the size of the added particles, the smaller the grain size and the clearer the grain outline for the multi-composite material. After adding 30 nm SiO2 particles, the crystallinity of the material increases significantly. The microstructure formed by the addition of 100 nm SiO2 particles effectively restricts molecular chain movement and makes it difficult to establish the polarization of the composite. The incorporation of large-size particles can reduce the proportion of the crystalline structure for the material as a whole, resulting in the formation of a new structure to promote charge transfer. Among the three kinds of SiO2 particles, the addition of 30 nm SiO2 particles can effectively suppress the space charge, and the composite material has the lowest residual space charge after depolarization. The addition of 100 nm SiO2 particles can cause the accumulation of many homopolar charges near the anode.

Differences among SiO2, TiO2, and Ti in the anti-foaming mechanism of chemically bonded silicate coatings

Potassium silicate coating foams seriously at high temperature. SiO2, TiO2 and Ti particles were added to solve this problem. Micro-morphologies, phase composition, mass change kinetics were analyzed, porosity and volatilizable water contents (κ0) of coatings were calculated to reveal the effects of adding SiO2, TiO2, and Ti particles on the foaming behavior of potassium silicate coatings at 500 °C. The higher the κ0, the more severe the foaming becomes. Results shows that addition of fillers improved the anti-foaming resistance due to volume occupier effect. Among them, SiO2 particles did not alter κ0 of the as-prepared coatings due to similar tetrahedral structure with silica, addition of TiO2 particles increased κ0 because titania can form more -Ti-OH groups than silica, Ti particles decrease κ0 because dissolved Ti4+ ions can decrease the number of the pending -Si-OH bonds. Combined with the volume expansion occurred due to the oxidation of Ti particles during heat treatment, potassium silicate coating modified by 30 wt% Ti exhibited the best anti-foaming performance with the lowest porosity, at 1.8%.

Shear thickening fluids in cork composites for impact mitigation: the role of fumed silica concentration

Cork composites have shown excellent potential in impact mitigating systems. Their sustainability greatly surpasses the currently used solutions. In addition, recent advances in developing cork composites with shear thickening fluids (STFs) have demonstrated exciting results for impact mitigation. This study explores different STF formulations based on polyethylene glycol (PEG), with a molecular weight of 400 g/mol, and SiO2 particles, investigating their application in layered cork composites for impact mitigation. Different STF formulations are investigated by processing suspensions with different fumed silica concentrations ranging from 10 to 60 wt.%. Using a cone–plate configuration, rheological measurements were conducted on these suspensions, which were then employed as an interfacial layer in agglomerated cork composite layered structures. These hybrid composites were then subjected to 20 J impact tests. PEG 400 exhibited fluid final states for silica concentrations up to 30 wt.% and crystallised at higher concentrations. Based on the results, STF within cork layers was positive regarding impact force reduction, drawing insights for future application of STF suspensions in cork composites for impact mitigation.Graphical abstract