Incorporation Of SiO2 Research Articles

SiO2/carbon fiber-reinforced polypropylene–thermoplastic polyurethane composites: electrical conductivity and mechanical and thermal properties

To achieve electrical conductive composites, carbon fibers (CFs) were introduced to polypropylene–thermoplastic polyurethane (PP/TPU) blends. In combination, a definite amount of silica (SiO2) nanoparticles were added as reinforcing agents to impregnate CFs and further improve the mechanical, thermal and electrical properties of CFs-modified PP/TPU composites. These quaternary composites were investigated by X-ray diffractometry technique, thermogravimetric analysis, scanning electron microscopy (SEM), mechanical measurement and electrical conductivity test. The results demonstrated that the crystallinity and flow rate of PP/TPU composites dropped after compounding with CFs, though they increased by the addition of SiO2. Both CFs and SiO2 improved the impact and tensile strength of quaternary composites, which were arising from the large aspect ratio of CFs and the reinforcement effect of SiO2 nanoparticle, respectively. Furthermore, CFs–PP/TPU and (CFs + SiO2)–PP/TPU composites exhibited superior thermal stability over PP/TPU composites, and (3CFs + 3SiO2)–PP/TPU composite exhibited a maximum value. It is attributed to the restriction of polymer chain motion created by the CF fillers and the insulating effect of SiO2. The SEM micrographs revealed the presence of plastic bands for CFs–PP/TPU and (CFs + SiO2)–PP/TPU composites and more refined arrangement of the fibers after incorporation of SiO2. This refinement resulted in higher electrical conductivity of (CFs + SiO2)–PP/TPU composites compared with CFs–PP/TPU composites.

Preparation of a novel composite based polyester nonwovens with high mechanical resistance and wash fastness properties

In this work, polyester fiber (PET) were functionalized by oxides (Ox) like titanium dioxide (TiO2), zinc oxide (ZnO) and silicon dioxide (SiO2), using polyvinylidene fluoride (PVDF) as binder to obtain a PET-PVDF-Ox material. Chitosan polymer (CT) was further grafted as coating layer to improve the surface compatibility, resulting in the PET-PVDF-Ox-CT composite. The obtained products were thermally pressed and fully characterized. The chemical coatings, physical and thermal properties were investigated. It was found that coated PET nonwoven is highly hydrophobic materials with good diffusion resistance. Incorporation of TiO2, ZnO and SiO2 resulted in the formation of strong cross-linked CT network, producing improved dripping resistance of PET nonwoven. In addition, the modification steps allowed increasing significantly the mechanical resistance. This was explained in terms of improved surface compatibly and interfacial bonding occurred in the matrix. Moreover, soil release tests confirmed the high durability against washing for PET-PVDF-Ox-CT composite. This work allowed developing a facile process for the fabrication of new composite based nonwovens with satisfactory durability and high mechanical resistance.

Thermal, mechanical and antibacterial properties of water-based acrylic Polymer/SiO2–Ag nanocomposite coating

This work aims to emphasize the effect of SiO2–Ag hybrid nanofillers on the thermal, mechanical and antibacterial properties of water-based acrylic coating. SiO2–Ag hybrid nanofillers were successfully synthesized and dispersed into water-based acrylic coating at the concentrations of 0.5–4 wt%. The mechanical tests indicated that the incorporation of SiO2–Ag nanofillers into the water-based acrylic coating had slightly improved adhesion of the coating and had significantly enhanced its abrasion resistance and its thermal stability. The coating with 2 wt% of the nanofillers had the highest values of adhesion (2.61 N/mm2), abrasion resistance (115.78 l/mil) and thermal stability (T5% = 340.14 °C). The antibacterial test against E. coli bacteria showed the antibacterial activity of SiO2–Ag nanofillers embedding in acrylic emulsion polymer matrix was comparable to that of AgNPs aqueous solution.

The effect of silica additive on the structural and luminescence properties of Eu3+/Tb3+ co-doped metaphosphate glasses

In this paper, we investigate the effect of silica additive on the structural and luminescence properties of Eu3+ and Eu3+/Tb3+co-doped sodium-calcium phosphate glasses. Eu3+ doped phosphate glasses have been prepared using melt-quenching technique and characterized through X-ray diffraction (XRD), differential thermal analysis (DTA), Fourier Transform Infrared (FTIR), Raman spectroscopy, ultraviolet–visible (UV–Vis) and luminescence measurements at room temperature. The incorporation of SiO2 led to an increase of glass transition temperature (Tg), indicating an improvement of glass network rigidity. This result was correlated with FTIR and Raman investigations which revealed the occurrence of more hydration-resistant POSi bonds. An intense red luminescence has been observed due to 5D0 → 7F2 transition of Eu3+ ions in these glasses. The luminescence spectra for Eu3+/Tb3+ co-doped phosphate glasses were then recorded with various Eu3+:Tb3+ molar ratio. Dependence of luminescence lifetimes on the increase of Eu3+: Tb3+ molar ratio was investigated. It was observed that the energy transfer process occurs from Tb3+ to Eu3+ in the studied glasses. Our results show that a tuneable color is achieved when Eu3+: Tb3+ molar ratio changed. The variation of the excitation wavelength can also tune the luminescence spectra of the new phosphate glasses.

In Situ SiO2 Passivation of Epitaxial (100) and (110)InGaAs by Exploiting TaSiO x Atomic Layer Deposition Process.

In this work, an in situ SiO2 passivation technique using atomic layer deposition (ALD) during the growth of gate dielectric TaSiOx on solid-source molecular beam epitaxy grown (100)InxGa1–xAs and (110)InxGa1–xAs on InP substrates is reported. X-ray reciprocal space mapping demonstrated quasi-lattice matched InxGa1–xAs epitaxy on crystallographically oriented InP substrates. Cross-sectional transmission electron microscopy revealed sharp heterointerfaces between ALD TaSiOx and (100) and (110)InxGa1–xAs epilayers, wherein the presence of a consistent growth of an ∼0.8 nm intentionally formed SiO2 interfacial passivating layer (IPL) is also observed on each of (100) and (110)InxGa1–xAs. X-ray photoelectron spectroscopy (XPS) revealed the incorporation of SiO2 in the composite TaSiOx, and valence band offset (ΔEV) values for TaSiOx relative to (100) and (110)InxGa1–xAs orientations of 2.52 ± 0.05 and 2.65 ± 0.05 eV, respectively, were extracted. The conduction band offset (ΔEC) was calculated to be 1.3 ± 0.1 eV for (100)InxGa1–xAs and 1.43 ± 0.1 eV for (110)InxGa1–xAs, using TaSiOx band gap values of 4.60 and 4.82 eV, respectively, determined from the fitted O 1s XPS loss spectra, and the literature-reported composition-dependent InxGa1–xAs band gap. The in situ passivation of InxGa1–xAs using SiO2 IPL during ALD of TaSiOx and the relatively large ΔEV and ΔEC values reported in this work are expected to aid in the future development of thermodynamically stable high-κ gate dielectrics on InxGa1–xAs with reduced gate leakage, particularly under low-power device operation.

Low temperature synthesis of pure and Fe-doped HfSiO4: Determination of Si and Fe fractions by neutron activation analysis

A new method of synthesis of hafnium silicate HfSiO4 (also known as hafnon) is reported. We observed a self-controlled incorporation of SiO2 from the quartz tube in which a sample of hafnium oxide nanoparticles was heated. This approach was then adapted to Fe-doped hafnon production. Sample structure, morphology and composition were characterized by X-ray diffraction, electron microscopy and neutron activation analysis. Diffraction data has shown that lattice parameters of doped HfSiO4 thus obtained are very close to those previously known for bare hafnon. The hafnon-like phase stabilized at T = 900 °C which is about 500 °C lower than the corresponding transition of bare bulk hafnium silicate. The fractions of Si and Fe in the composite matrices were determined with neutron activation analysis. These results completed by X-ray diffraction data allowed to assume that (i) Fe initially substituted Hf in the HfO2 lattice; (ii) there was no migration of iron atoms from Hf to Si sites at the formation of hafnon-like phase; (iii) doped and undoped hafnium oxide has taken as much Si from the quartz as was needed for the arrangement of Fe1-xHfxSiO4 tetragonal system, 0≤x<0.2. Our results are consistent with those obtained for similar materials, such as metal (Fe,V) doped zircon, where the dopant also demonstrated catalytic effect on phase stabilization.

Controllable synthesis of TiO 2 /ATO conductive composite: effects of TiO 2 surface properties

The effect of the TiO2 surface property on the conductivity of TiO2/antimony-doped tin oxide (ATO) has been revealed by the substrate modification with SiO2 and ZrO2. Their morphology, structural, and electric characteristics were investigated through field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical impedance spectra. The surface character of the raw and modified TiO2 particles in water was investigated. The results indicated that the negatively charged substrate (−29.7 mV) was formed through the incorporation of SiO2 coating, which facilitated the uniform deposition of positively charged ATO precursors further significantly improved the conductivity of TiO2/ATO composite. Conversely, the conductivity of TiO2/ZrO2–ATO composite decreased due to the increase of electrostatic repulsion from the positively charged surface (+55.3 mV) of the substrate. The results confirmed the feasibility of the method proposed in this work.

Nano/microstructure decorated thin film composite poly (arylene sulfide sulfone) membrane constructed by induced fouling in organic solvent ultrafiltration

In this study, novel thin film composite membranes with nano/macrostructure decorated surface were fabricated by deposition of poly (arylene sulfide sulfone) (PASS) polymer chains on oxidized poly (arylene sulfide sulfone) (O-PASS) support membrane during organic solvent ultrafiltration. Interestingly, the obtained membranes exhibited a rough surface structure composed of ordered arranged polymeric nodules with size ranging from nanoscale (100 nm) to macroscale (5 μm). Additionally, these membranes showed an improved, ultrahigh rejection of direct red 23, reactive blue 2, demonstrating their potential application for the reuse of dyes in wastewater. Furthermore, this novel synthesis approach of thin film composite membranes has great advantages in incorporating nanoparticles because of the facile process, the low consumption of nanoparticles and the high content of nanoparticles in the thin layer. During the whole thin layer synthesis process, only 2 mg of nanoparticles were used and thin layers with nanoparticles content of 20% were obtained. After the incorporation of candle soot, SiO2 and ZIF-8 in the separation layer, both the water permeation and rejection of direct red 23, reactive blue 2 and reactive orange 16 were greatly improved. Therefore, this study provides a novel and simple fabrication method for thin film composite membranes, which has advantages in incorporating nanoparticles in the thin separation layer to endow the membrane with an improved performance.

IR Spectroscopic Study of Interatomic Interaction in [(CoFeB)60C40/SiO2]200 and [(CoFeB)34(SiO2)66/C]46 Multilayer Nanostructures with Metal-Containing Composite Layers

This paper presents an IR spectroscopic study of chemical bonds between components of amorphous [(CoFeB)60C40/SiO2]200 and [(CoFeB)34(SiO2)66/C]46 multilayer nanostructures (MNS’s) made up of metal-containing composite layers and different interlayers, which influence their electromagnetic properties. Our results demonstrate that, even though the MNS’s have identical elemental compositions, their IR spectra differ significantly. The reason for this is that the main contribution to the IR spectrum of the [(CoFeB)60C40/SiO2]200 MNS is made by its SiO2 interlayers. The formation of other bonds with oxygen and silicon is blocked by the carbon present in the (CoFeB)60C40 composite layers, as evidenced by the presence of the strongest mode in the IR spectra of this structure, which corresponds to boron carbide, BC. The considerable intensity redistribution to the low-frequency region in the IR spectrum of the [(CoFeB)34(SiO2)66/C]46 MNS, containing carbon interlayers, is due to the incorporation of nominal SiO2 into the metal-containing composite layers and the partial redistribution of oxygen bonds from the SiO2 to the 3d transition metals, resulting in the formation of metal oxides and a silicon suboxide. The interaction of the carbon present in the interlayers between the composite layers with elements of the composite layers, in particular with boron, is considerably weaker in comparison with the other MNS, [(CoFeB)60C40/SiO2]200, which has oxide interlayers.

Effect of SiO2, PVA and glycerol concentrations on chemical and mechanical properties of alginate-based films

Sodium alginate (SA)/polyvinyl alcohol (PVA)/SiO2 nanocomposite films were prepared by in situ polymerization through solution casting and solvent evaporation. The effect of different SA/PVA ratios, SiO2, and glycerol content on the mechanical properties, water content, water solubility, and water vapor permeability were studied. The nanocomposite films were characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and thermal stability (thermogravimetric analysis/differential thermogravimetry) analyses. The nanocomposites showed the highest values of mechanical properties, such as SA/PVA ratio, SiO2, and glycerol content was 7:3, 6wt.%, and 0.25g/g SA, respectively. The tensile strength and elongation at break (E%) of the nanocomposites increased by 525.7% and 90.7%, respectively, compared with those of the pure alginate film. The Fourier transform infrared spectra showed a new SiOC band formed in the SA/PVA/SiO2 nanocomposite film. The scanning electron microscopy image revealed good adhesion between SiO2 and SA/PVA matrix. After the incorporation of PVA and SiO2, the water resistance of the SA/PVA/SiO2 nanocomposite film was markedly improved. Transparency decreased with increasing PVA content but was enhanced by adding SiO2.

Tuning the structural and optical properties in cobalt oxide-doped borosilicate glasses

Borosilicate glass systems with composition xSiO2 - (50-x) B2O3 - 30Na2O - 19.5ZnO - 0.5CoO (x = 0, 5, 10 and 20 mol. %) have been successfully prepared following the traditional melt quenching technique. The incorporation of SiO2 into borate glass network was found to tune its properties at different aspects, as probed by a set of complementary experimental techniques. The density of such boraosilicate glasses was decreased by SiO2 addition, thus, rendering the glassy network less tightly packed. In addition, the BO4 structural units were found to increase with SiO2 content as obtained from comparative FTIR spectra. Interestingly, the optical properties of such borosilicate glasses could be tuned through SiO2 addition. In particular, the optical band gaps attain larger values together with noticeable suppression of the band tails associated with defective structures upon SiO2 addition. Further insights into the crystal field interaction and d-levels splitting were obtained by a detailed deconvolution procedure applied to the characteristic absorption bands of Cobalt. The outcome of such a process revealed noticeable reductions in the ligand field strength and the associated d-levels splitting with SiO2 additives. Furthermore, the octahedral symmetry contribution was increased in borosilicate compared to the pure borate glasses as inferred from the oxidation states of Co ions probed by ESR. The present system combines the advantageous of the pure borate and silicate glasses and, therefore, offers an alternative candidate for optical applications.

Incorporation of SiO2 and TiO2 additives into expanded polystyrene foam using physical vapour deposition technique

This article analyses possibility to use physical vapour deposition (PVD) technique for incorporation of pure SiO2 and TiO2 additives into thermal sensitive polymer (expanded polystyrene). SiO2 and TiO2 films were deposited on non-expanded polystyrene (PS) beads. These beads were expanded and molded into one piece foam (expanded polystyrene (EPS)). During the expansion process, SiO2 and TiO2 films were fractured. SiO2 / TiO2 films after expansion were distributed with even regions around the expanded PS beads. Results showed that fractured SiO2 and TiO2 films were observed on EPS foam without any impurities. Such method could be used for pure additives incorporation into polymers, where relatively homogenous distribution of additives in the polymer bulk is required.

Glass transition of poly (methyl methacrylate) filled with nanosilica and core-shell structured silica

Core-shell (CS) nanocomposite particles with 53.4 wt% cross-linked poly (methyl methacrylate) (PMMA) shell of 11.6 nm in thickness were fabricated via miniemulsion polymerization of methyl methacrylate in the presence of modified nanosilica. The influence of nanosilica and CS nanoparticles on glass transition and segmental dynamics of PMMA in the nanocomposites prepared via solution casting was compared. The remarkable depression (≥10 °C) of glass transition temperature (Tg) induced by the incorporation of SiO2 and CS was both observed at low loadings. Here, different mechanisms were responsible for the effect of SiO2 and CS on the segmental acceleration of PMMA matrix. The formation of rigid amorphous fraction (RAF) layer around SiO2 with the thickness of 16.4 nm led to the adjacent molecular packing frustration, while the “lubrication” effect of nonwetting interface between the grafted crosslinked chains and matrix chains resulted in the segmental acceleration and the reduction of dynamic fragility.

The curing and degradation kinetics of modified epoxy–SiO2 composite

Composites (SiO2-EC) were prepared by 4,5-epoxycyclohexane 1,2-dicarboxylic acid dilycidyl (TDE-85) epoxy resin in the presence of SiO2 and cured by 2-aminobenzothiazole (2-ABZ). The curing kinetics and degradation kinetics of SiO2-EC were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), respectively. Then, the kinetic parameters were evaluated using non-isothermal mode and several kinetic methods, including Flynn–Wall–Ozawa (FWO), Friedman–Reich–Levi (FRL) and Malek methods. The results show that the experimental values of DSC and TG can be well described by autocatalytic model and nth model, respectively. The obtained equation of autocatalytic model is \(\frac{{{\text{d}}\alpha }}{{{\text{d}}t}} = 1.921 \times 10^{8} \exp \left( { - \frac{{6.783 \times 10^{4} }}{{{{R}}T}}} \right)\alpha^{0.995} (1 - \alpha )^{1.910}.\) All of these results are beneficial for studying the application of modified epoxy–SiO2 composite. A reliable and reasonable curing process between T i0 (379 K) and T f0 (472 K) is obtained by using extrapolation method. The cured SiO2-EC (the content of SiO2 is 25%) that exhibits excellent thermal stability with the initial decomposition temperature at 5% mass loss (IDT) is 572 K, increasing about 11 K compared with pure epoxy resin. It may be contributed to the reasonable and effective curing process obtained from the studying of curing kinetics of SiO2-EC and the synergistic effects obtained via the incorporation of SiO2.

Corrosion Behavior and Microhardness of Ni-P-SiO2-Al2O3 Nano-composite Coatings on Magnesium Alloy

In the present work, nano-composites of Ni-P-SiO2-Al2O3 were coated on AZ91HP magnesium alloy. The surface morphology of the nano-composite coating was studied by field emission scanning electron microscopy (FESEM). The amount of SiO2 in the coating was determined by energy-dispersive analysis of x-ray (EDX), and the crystalline structure of the coating was examined by x-ray diffractometer (XRD). All the experiments concerning the corrosion behavior of the coating carried out in 3.5 wt.% NaCl solution and evaluated by electrochemical impedance spectroscopy (EIS) and polarization technique. The results showed that an incorporation of SiO2 and Al2O3 in Ni-P coating at the SiO2 concentration of 10 g/Land 14 g/LAl2O3 led to the lowest corrosion rate (icorr = 1.3 µA/cm2), the most positive Ecorr and maximum microhardness (496 VH). Furthermore, Ni-P-SiO2-Al2O3 nano-composite coating possesses less porosity than that in Ni-P coating, resulting in improving corrosion resistance.

Characterization of Ni-P-SiO2-Al2O3 nano-composite coatings on aluminum substrate

In the present work, nano-composites of Ni-P-SiO2-Al2O3 were coated on a 6061 aluminum substrate. The surface morphology of the nano-composite coating was studied by field emission scanning electron microscopy (FESEM). The amount of SiO2 in the coating was determined by Energy Dispersive Analysis of X-Ray (EDX) and the crystalline structure of the coating was examined by X-ray diffractometer (XRD). All the experiments concerning the corrosion behavior of the coating carried out in 3.5%wt NaCl solution and evaluated by electrochemical impedance spectroscopy (EIS) and polarization technique. The results showed that an incorporation of SiO2 and Al2O3 in Ni-P coating at the SiO2 concentration of 10 g/L and 14 g/L Al2O3 led to the lowest corrosion rate (icorr = 0.88 μA/cm2), the most positive Ecorr and maximum microhardness (537 μHV). Furthermore, increasing the amount of nanoparticles in the coating was found to decrease CPEdl and improve porosity.

Controlling Hydrodeoxygenation of Stearic Acid to n‐Heptadecane and n‐Octadecane by Adjusting the Chemical Properties of Ni/SiO2–ZrO2 Catalyst

AbstractA series of SiO2–ZrO2 mixed oxides with varying SiO2 concentrations were hydrothermally synthesized and used as support for Ni in the hydrodeoxygenation of stearic acid. ZrO2 provides a relatively low surface area and only Lewis acid sites, and Ni supported on ZrO2 produces n‐heptadecane from stearic acid through hydrogenation and decarbonylation. The SiO2–ZrO2 mixed oxides have a higher specific surface area than ZrO2 as well as an unprecedented spherical and nanolayered morphology. Brønsted acid sites were created by the incorporation of SiO2 into ZrO2, promoting the hydrodeoxygenation activity of Ni and specifically opening a new reaction route to n‐octadecane through the dehydration of 1‐octadecanol intermediate into 1‐octadecene with subsequent hydrogenation.

One-pot synthesis of mesoporous Cu-SiO2-Al2O3 bifunctional catalysts for hydrogen production by dimethyl ether steam reforming

Mesoporous Cu-SiO2-Al2O3 bifunctional catalysts with highly dispersed active sites and increased acid amount were synthesized via a modified evaporation induced self-assembled (EISA) method and firstly used for dimethyl ether steam reforming (DME SR). Various techniques including XRD, nitrogen adsorption-desorption, N2O chemisorption, H2-TPR, NH3-TPD, TEM, FT-IR and 27Al MAS NMR were employed to characterize the prepared catalysts. The Cu-SiO2-Al2O3 catalyst calcinated at 700°C with 7.5% Cu and 17.5% Si exhibited the highest DME conversion rate up to 100% and H2 yield of 90%, and good reaction-regeneration performance. The long-range ordered mesoporous structure, improved specific surface area and pore volume, and highly dispersion of Cu and CuAl2O4 nanopaticles were obtained after the incorporation of SiO2, which were found to be influential to the enhanced catalytic performance. Notably, the added SiO2 helped to form Lewis acid, leading to a huge increase in solid acid amount, which further improved the DME hydrolysis activity.

Study on release of naproxen and metformin encapsulated in biopolymer-inorganic mesoporous matrices as controlled drug-delivery systems

In this study, a new methodology was applied for controlling the release of different drugs by encapsulating them in organic-inorganic hybrids via sol-gel technique. The assembled organic-inorganic hybrids had diverse BET surface area, porosity, and high heat resistance. The synthesized organic-inorganic hybrids were based on zirconium(IV) propoxide, and tetraethyl orthosilicate as precursor of inorganic network, and chitosan or N-triethylchitosan as organic or biopolymer components. In these hybrid composites, drug and biopolymer were coated with a mesoporous inorganic material. FT-IR, FE-SEM, DSC, BET, XRD techniques, and Zeta potential analysis used for investigating the formation of metformin/chitosan@ZrO2 and sodium naproxen/N-triethylchitosan@SiO2 hybrid composites. Then for investigating the role of sol-gel process, the release of metformin and sodium naproxen in the prepared hybrid composites was investigated as model drugs. Compare to drug/biopolymer composite, incorporation of ZrO2 or SiO2 coating enhanced the drug entrapment appreciably, and naturally reduced the rate of drug release. For example, the metformin/chitosan composite without ZrO2 coating released the whole drug in less than10 h in pH 7.4 when the composite coated with ZrO2 released the entrapped drug after 25 h.

In-situ synthesis of SiO2@MOF composites for high-efficiency removal of aniline from aqueous solution

A series of SiO2@aluminum-MOF(MIL-68) composites with different SiO2 loadings have been synthesized by a simple and mild compositing strategy for high-efficiency removal of aniline. As evidenced from SEM and TEM images as well as the particle size distribution, the incorporation of SiO2 can improve the dispersity of MIL-68(Al) in composites, and result in the smaller particle size than that of pristine MIL-68(Al). Besides, the adsorption of aniline over SiO2, MIL-68(Al), the physical mixture of these two materials, and SiO2@MIL-68(Al) composites was investigated comparatively, demonstrating a relatively high adsorption capacity (531.9mgg−1) of 7% SiO2@MIL-68(Al) towards aniline. Combining the ultrafast adsorption dynamics (reaching equilibrium within 40s) and great reusability, 7% SiO2@MIL-68(Al) shows excellent adsorption performance. This indicates that the SiO2@MIL-68(Al) composites possess great potential applications as a kind of fascinating adsorbent in water pollution protection.