Silane Concentration Research Articles

Enhanced interfacial dielectric polarization in PVDF-HFP copolymer with treating PPy by using silane coupling agent

Dielectric materials are polar materials for energy storage applications such as capacitors, transformer, and other electrical devices. The great dielectric properties generally depend on easily switchable polarization and higher-order structure in a material. Filler composite in the flexible dielectric polymer is then considered to rearrange polymer chain. However, the filler becomes agglomeration easily at high loading content in polymer, resulting in high energy loss and low electrical breakdown. This work presents the treated Polypyrrole (PPy) filler by 3-Aminopropyltriethoxysilane for avoiding agglomeration in PVDF-HFP thin film. These 30 μm PVDF-HFP film thickness is fabricated by tape casting method with N, N-dimethylformamide (DMF) solvent. The distributions of PPy filler on PVDF-HFP are observed by SEM image. Dielectric constant, dielectric loss, and conductivity are analyzed. As a result, the maximum silane content was found on 1 wt% for 1 wt% PPy/PVDF-HFP to maximized dielectric constant and reduce dielectric loss and conductivity. The conductive of PPy filler was lowered by covering with electrical insulating silane, resulting in decreased dielectric loss and conductivity. Then, polymer chain with silane bonding easily polarized under the electric field, resulting in an intensification of dielectric constant around 2.5 times compared with non-silane. Afterward, this dielectric constant clearly decreased when it reached to exceeded silane content as 5-20 wt%. Treated PPy with the suitable silane content in PVDF-HFP performs good dielectric properties for advanced energy storage in this work.

Synthesis and surface modification of light emitting silicon nanoparticles using non-thermal plasma techniques

We have synthesised silicon nanoparticles (Si-NPs) with photoluminescence ranging from blue to IR spectral region using a low-pressure RF plasma in a flow-through glass tube reactor. The spectral position of photoluminescence band of Si-NPs is controlled by the synthesis parameters such as plasma power, silane and hydrogen concentration and pressure in the working area. Modification of Si-NPs surface both on air after the synthesis and in the vacuum chamber by second plasma in methylsilane atmosphere causes a blue spectral shift of the photoluminescence band.

Effect of partial substitution of superplasticizer by silanes in Portland cement pastes

This work evaluated the effect of partially replacing a superplasticizer by silanes on the fresh and hardened properties of Portland cement pastes. For this, pastes with water/cement ratio of 0.20 and 25 and 50% replacement of a polycarboxylate-ester-based superplasticizer by tetraethoxysilane (TEOS), 3-glycidoxypropyltrimethoxysilane (GPTMS) and aminoethylaminopropyltrimethoxysilane (AEAPTMS) were produced. The specific gravity, entrapped air content and mini-slump of the pastes were determined in the fresh state. The hydration kinetics was evaluated by isothermal calorimetry up to 120 h. Finally, the compressive and flexural strength of the pastes, as well as the ratio between them (referred to as toughness) were determined at 7 and 28 days. The results showed that 25% replacement by either the silanes increased the mini-slump and decreased the air content of the pastes in comparison to the reference. In contrast, 50% incorporation of GPTMS and AEAPTMS increased the air content and decreased the mini slump of the pastes, while 50% TEOS did not significantly affected these properties. The isothermal calorimetry indicated that TEOS reduced the induction period of the pastes, while the other silanes increased it, delaying the acceleration period start in up to 53 h in comparison to the reference. In addition, the increase in both silane content progressively increased the cumulative heat up to 120 h, reaching values 11% higher than the reference. The incorporation of TEOS progressively increased the flexural strength, while did not significantly changed the compressive strength, both at 7 and 28-day. The same trend was found for the compressive strength of the pastes containing GPTMS and AEAPTMS, while the flexural strength of these pastes decreased as the replacement level increased. Finally, 7 and 28-days toughness of the pastes increased as the content of TEOS increased, while no clear trend was found for GPTMS and AEAPTMS.

Study of the wettability and the corrosion protection of the hybrid silane (3-aminopropyl) triethoxysilane (APTES) and (3-glycidyloxypropyl) trimethoxysilane (GPTMS) film on galvannealed steel

In this work, the wettability of the galvannealed surface pretreated with the hybrid silane APTES/GPTMS film was measured by sessile drop method. The coatings were applied on the substrate from dip-coating method and dried in an oven. The study followed an experimental factorial design, 3³, with contact angle as response. The corrosion resistance was evaluated by electrochemical techniques and the surface morphology was characterized by scanning electron microscopy. The wettability results showed the best condition for galvannealed steel pretreated with the hybrid silane film for 2:1 APTES:GPTMS ratio, 2% silane concentration and 150 min of hydrolysis time, because the result may be related to a higher rate of hydrolysis of the silanes that is influenced by both the functional group present and by the type and number of hydrolyzed groups, resulting consequently in a higher availability of silanol groups in solution, promoting a greater crosslinking of the film on the metallic substrate. Keywords: hybrid silane, corrosion, galvannealed steel, pretreatment, wettability.

Morphology engineering of silicon nanoparticles for better performance in Li-ion battery anodes.

Amorphous silicon nanoparticles were synthesized through pyrolysis of silane gas at temperatures ranging from 575 to 675 °C. According to the used temperature and silane concentration, two distinct types of particles can be obtained: at 625 °C, spherical particles with smooth surface and a low degree of aggregation, but at a higher temperature (650 °C) and lower silane concentration, particles with extremely rough surfaces and high degree of aggregation are found. This demonstrates the importance of the synthesis temperature on the morphology of silicon particles. The two types of silicon nanoparticles were subsequently used as active materials in a lithium half cell configuration, using LiPF6 in an alkylcarbonate-based electrolyte, in order to investigate the impact of the particles morphology on the cycling performances of silicon anode material. The difference in morphology of the particles resulted in different volume expansions, which impacts the solid electrolyte interface (SEI) formation and, as a consequence, the lifetime of the electrode. Half-cells fabricated from spherical particles demonstrated almost 70% capacity retention for over 300 cycles, while the cells made from the rough, aggregated particles showed a sharp decrease in capacity after the 20th cycle. The cycling results underline the importance of Si particle engineering and its influence on the lifetime of Si-based materials.

An ultrasensitive electrochemical immunosensor platform based on disposableITO electrode modified by 3-CPTMS for early detection of parathyroid hormone

Parathyroid hormone (PTH) is a polypeptide containing 84 amino acids secreted by cells of the parathyroid glands. Imbalances of parathyroid levels cause medical problems such as osteoporosis, mental disorders, pancreatitis, kidney stones, cancer, and other symptoms. In this study, we aimed to design an ultrasensitive electrochemical immunosensor for PTH detection. Indium tin oxide (ITO) was used as an electrode for electrochemical impedance spectroscopy (EIS) measurements. ITO sheets were modified by using 3-cyanopropyltrimethoxysilane (3-CPTMS) self-assembled monolayers (SAMs) for immobilizing the anti-PTH antibody via covalent interactions. Cyclic voltammetry (CV) and EIS methods were applied to characterize immobilization steps. Therefore, 1% was selected for an optimal concentration of silane, 10 ng/mL was selected as an optimal concentration of anti-PTH, and 30 and 45 min were selected as optimal incubation times for anti-PTH and PTH, respectively. PTH antigen was determined in the concentration range from 0.05 fg/mL to 150 fg/mL. To detect the analytical characterization of the 3-CPTMS modified immunosensor, linear range, repeatability, reproducibility, Kramers-Kronig transform, and regeneration studies were performed. Also, the shelf life of the developed biosensor was investigated. Finally, real human serum samples were analyzed with the PTH immunosensor. The results showed that the designed biosensor system has high potential for early detection for medical treatments.

The Effect of Filler Loading and Silane Treatment on Kenaf Core Reinforced Polyurethane Composites: Mechanical and Thermal Properties

This investigation was aimed to study the mechanical and the thermal properties behavior of kenaf core (untreated and treated with silane)–polyurethane composites. Three different types of silane coupling agent were used to treat kenaf core (KC) which were, trimethoxyphenylsilane (TMPS), vinyltrimethoxysilane (VTMS), and tetramethoxyl orthosilicate (TMOS). The concentration of silane was varied from 0 to 3%. Silanization of KC filler is measured by the weight percentage gain (WPG), scanning electron microscopy and energy dispersive X-ray analysis. Kenaf core–polyurethane (KCP) composites were prepared using a one-shot process. Tensile, flexural and thermogravimetric analysis was carried out it to study mechanical and thermal properties of the KCP. Among the three types of silane, the most effective one for property improvement was TMPS. The results from TMPS showed tensile and flexural agreed to each other that TMPS was the suitable chemical to be used as a coupling agent for KC filler in the preparation of KCP composite.

Fused Deposition Modeling of Poly (Lactic Acid)/Walnut Shell Biocomposite Filaments—Surface Treatment and Properties

This paper presents the study of the properties of objects that were fabricated with fused deposition modeling technology while using Poly (lactic acid)/Walnut shell powder (PLA/WSP) biocomposite filaments. The WSP was treated while using NaOH followed by silane. The infrared spectrum of treated and untreated WSP was characterized. The result was that thermal and mechanical properties could be improved by adjusting the concentration of silane. The experimental results showed: the surface compatibility between WSP and PLA was dramatically improved through treatment with KH550. The crystalline, thermal gravity, and thermal degradation temperatures of biocomposite with untreated WSP were improved from 1.46%, 60.3 °C, and 239.87 °C to 2.84%, 61.3 °C, and 276.37 °C for the biocomposites with treated WSP, respectively. The tensile, flexural, and compressive strengths of biocomposites were raised each by 8.07%, 14.66%, and 23.32%. With the determined silane concentration, PLA/10–15 wt.% treated WSP biocomposites were processed and tested. The results showed that the tensile strength was improved to 56.2 MPa, which is very near to that of pure PLA. Finally, the porous scaffolds with controllable porosity and pore size were manufactured.

Combination of a millimeter scale reactor and gas chromatography-mass spectrometry for mapping higher order silane formation during monosilane pyrolysis

The formation of higher order silanes during monosilane pyrolysis is studied using a millimeter scale pyrolysis reactor combined with a tailormade gas chromatography–mass spectrometry (GC–MS) setup. We use monosilane diluted in hydrogen and investigate the effects of monosilane inlet concentration (0–100%) and reactor temperature (450–530 °C) on the pyrolysis process. The applied GC–MS technique allows for absolute quantification of mono-, di- and trisilane, as well as relative quantification of higher order silanes with up to eight silicon atoms. We are able to differentiate between higher order silane isomers with up to five silicon atoms and to identify one cyclic silane with six silicon atoms. We find that the outlet concentration of the cyclic silanes as a function of reactor temperature and monosilane inlet concentration have characteristic differences from the outlet concentrations of their non-cyclic counterparts as a function of the same variables. Our data does thereby give experimental evidence for the special role of the cyclic silanes in the pyrolysis process, which has already been pointed to by other authors through numerical and theoretical works. Since cyclic silanes are key species in the particle formation process during monosilane pyrolysis, we hypothesize that avoiding cyclic species can help to reduce fines formation in monosilane pyrolysis reactors. Our detailed mapping of higher order silanes formation gives indications as to which process parameter combinations promote the formation of cyclic silanes and which do not.

Hydrolyzed wheat protein as a self-assembled reinforcing filler in synthetic isoprene rubber vulcanizates

Trypsin hydrolyzed gliadin (THGd) from wheat protein is utilized as a reinforcing filler in synthetic rubber. THGd self-assembles into a reinforcing filler phase during sulfur vulcanization of synthetic cis-1,4-polyisoprene rubber (IR), as observed by an increase in the β-sheet aggregation absorbance in Fourier transform infrared (FTIR) spectroscopy. The curing process is studied using differential scanning calorimetry (DSC). THGd filler interferes with the curing process resulting in more incomplete cure and a reduced induction time. Young’s modulus (E) increases with protein concentration, curing time, and silane coupling agent concentration. Moduli comparable to or greater than the IR Control are achieved at all tested protein loadings of 4–16 parts per hundred rubber (phr). Hysteresis decreases with curing time showing the formation of a more elastic network and increases with filler and silane concentration showing energy dissipation through filler re-arrangement and rubber molecule-filler particle detachment, respectively. Reduced swelling is observed with the addition of silane coupling agent as there are more protein-rubber interactions. The results suggest that quantities of THGd greater than 4 phr reinforce the rubber phase through continued aggregation into protein β-sheet nanostructures.

REINFORCED MECHANICAL PROPERTIES OF FUNCTIONALIZED SILICA AND EGGSHELL FILLED GUAYULE NATURAL RUBBER COMPOSITES

ABSTRACT Replacing synthetic fillers, which are commonly used to reinforce rubber, with bio-fillers has potential to improve the sustainability of rubber products. Eggshell (ES) (a powder with a maximum particle diameter of 9.4 μm and a median of 1.1 μm) was added to guayule natural rubber (GNR) composites to partially or fully replace bifunctionally silanized, high surface area, precipitated silica (BSS). The mixing energy consumption, mechanical properties, cross-link density, filler dispersion and final particle size, fracture surface morphology, and dyeability of GNR composites were characterized. ES filler effectively reinforced vulcanized GNR compared with unfilled vulcanized GNR. Energy consumption, modulus at 300% strain (M300), and hardness generally decreased with increasing ES fraction (decreasing BSS), but tensile strength, gel fraction, and elongation at break increased even where cross-link density and M300 were similar. Thus, composite cross-link density was not solely influenced by silane content as the ratio and loading of ES and BSS changed. The production of the composites reduced particle size to submicron size. Even a small amount of ES improved the dispersion of BSS filler particles in the composites and hence the mechanical properties. The contributions of the two fillers to the composite properties are explained. Linear mixed models were built to predict the mechanical properties of a broader range of GNR–ES–BSS composites, and r2 (the quality of the model predictability) was above 0.9 for all models. ES filled GNR, with or without BSS, can be dyed different colors for specific applications. The lower-cost, renewability, dyeability, and excellent performance of ES–GNR composites addresses the need for sustainable rubber products with low carbon footprint.

Synthesis of raspberry-like SiO2/polyacrylate nanocomposite latexes via a one-step miniemulsion polymerization and its film properties

Narrowly size-distributed raspberry-like SiO2/polyacrylate nanocomposite latexes were prepared by miniemulsion polymerization. The effects of tetraethyl orthosilicate (TEOS) and γ-(methacryloxypropyl) trimethoxy silane (KH570) content on the properties of composite emulsion and films have been investigated. Dynamic light scattering (DLS) analysis showed that the narrowly size-distributed nanocomposite latexes could be prepared by the 6–10 wt% TEOS dosage and 0–2.5 wt% KH570 dosage effectively. Centrifugal stability results indicated that narrowly size-distributed composite latex particles were beneficial to the stability of composite emulsion. The formation mechanism of raspberry-like nanocomposite latex particles was proposed by measuring the morphology evolution of composite latex particles during the polymerization process. The performance analysis of nanocomposite films showed that the raspberry-like nanocomposite latexes had excellent film properties. What is more, scanning electron microscopic (SEM) analysis indicated that SiO2 nanoparticles were uniformly dispersed on surface of the composite films prepared by 10 wt% TEOS and 1.5 wt% KH570, and a good interface was established in the films.

Transparent, mechanically strong, thermally insulating cross-linked silica aerogels for energy-efficient windows

Silica aerogels are transparent and excellent thermal insulators; however, application in energy-efficient windows has been elusive. The main reason is fragility that renders handling and processing extremely difficult. One way to overcome the fragility issue of silica aerogels is via cross-linking technology, in which a polymer is applied conformally over their entire skeletal framework. Extremely strong materials may be obtained by that approach; however, the penalty is loss of transparency. This study was designed to reach a compromise among those competing requirements. Aerogels based on co-gelation of tetramethylorthosilicate (TMOS) and 3-aminopropyltriethoxysilane (APTES) were prepared and were cross-linked with a triisocyanate (Desmodur N3200A). The two independent variables, the total silane concentration in the sol and the concentration of the monomer in the cross-linking bath, were varied according to a full-factorial model. The nanostructure was characterized with SEM and SAXS. The porous structure with N2 sorption. Properties of interest with respect to the intended application were the thermal conductivity, the elastic modulus, and the haze. The latter has two components, from the bulk and the surface. Cross-linking places the polymer inside secondary aggregates that behave as core–shell particles with increased scattering, due to refractive index mismatch. Surface haze can be minimized by molding with clean glass plates and careful handling. Guided by our statistical model, we demonstrate optimal samples with bulk densities in the range of 0.25–0.33 g cm−3, porosities in the range of 76–83% v/v, bulk haze around 10%, Young’s modulus in the range of 30–70 MPa, and thermal conductivities in the range of 18–22 mW m−1 K−1. Those samples were strong enough to be machined with conventional tools (band saws, diamond cutters), they displayed sufficient clarity, and their thermal conductivity was lower than that of still air.

Preparation of Peelable Coating Films with a Metal Organic Framework (UiO-66) and Self-Crosslinkable Polyurethane for the Decomposition of Methyl Paraoxon.

For the fabrication of a peelable coating material that decomposes methyl paraoxone (MPO), a nerve agent simulant, self-crosslinkable waterborne polyurethanes (PUs) containing silane groups at the ends and a metal organic framework (UiO-66) were synthesized. UiO-66 dispersed PU solutions for spray coating were prepared by controlling the amount of silane in PU and the content of UiO-66. PUs with a large amount of silane (more than 7.2 wt.%) were easily gelated by adding UiO-66 because the solution was changed from neutral (pH = 7.3) to strongly acidic (pH = 2.5). Therefore, the silane content in PUs should be carefully controlled for the fabrication of composite films. When UiO-66 was added to the PU with a silane content of 2.7 wt.%, the reinforcing effect by UiO-66 was observed up to 15.3 wt.%, but a further increase in UiO-66 content decreased both the tensile strength and the elongation. The peel strength of the PU composite films on polyethylene (PET) and glass substrates decreased with increasing UiO-66 content, but their MPO conversion increased with increasing UiO-66 content. The PU composite film with 49.5 wt.% of added UiO-66 showed the MPO conversion of 63.2% and was easily peeled off from PET and glass substrates.

Structural and mechanical characteristics of silane-modified PIPD/basalt hybrid fiber-reinforced polybenzoxazine composites

Typically, hybrid fibers reinforced composites have the potential to provide materials with excellent mechanical properties. However, cost-effective, lightweight, easily manufactured and high-performance materials are even more attractive for the market and the industry. In this work, newly designed hybrid poly-pyridobisimidazole (PIPD) and basalt fibers (BFs) reinforced polybenzoxazine composites were investigated. Initially, the fibers were chemically modified with silane GX-560 coupling agent. Afterwards, the hybrid combinations were included in the resin and cured. The Fourier transform infrared spectra showed the chemical bond that results when the silane is grafted. The X-ray photoelectron spectroscopy scan provided the fibers atomic content and showed that the silane content was effectively raised after treatment. The microhardness and impact properties were markedly improved, reaching the maximum value of 570 MPa and 18.44 kJ/m2, respectively, compared to the reference resin with 347 MPa and 1.6 kJ/m2. This was due to the high-performance PIPD and BFs inclusive of their good interfacial adhesion and scattering around the surface confirmed by the fibers’ pull-out void and the random dispersion seen in the scanning electron microscope images.

Effect of Silanization on the Magnetic and Microwave Absorption Properties of SrFe12O19 Nanostructure Particles

Strontium ferrite nanostructure particles (SrFe12O19), which have a ferrimagnetic nature, were synthesized by a co-precipitation process of chloride salts using a sodium hydroxide solution. The resulting precursors were heat-treated in a furnace at 1100°C for 4 h. After cooling in the furnace, the nanostructure particles were silanized using 3-methacryloxypropyltrimethoxy silane molecules. After applying the silane pretreatment to the surface of the nanoparticles, we studied the effects of the most influential silanizing parameters, including the silane concentration and hydrolyzing time, on the magnetic and microwave absorption properties of the samples. The hysteresis loops showed an optimum saturation magnetization of 0.065T for 1 h hydrolyzing time at 1.25 wt.% silane concentration; however, no change was detected in the coercivity by varying the two factors. The powders with optimum magnetic properties were used to manufacture the samples in order to study the microwave absorption properties. Employing silanized nanostructures resulted in a significant increase in the reflection loss (at the resonance frequency) from − 16 dB up to − 72 dB.

Si-doped polycrystalline via chemical deposition

Microcrystalline diamond films doped with silicon have been grown on aluminum nitride substrates by a microwave plasma CVD. The doping has been performed via adding silane in various concentrations to CH4–H2 reaction gas mixture in course of the deposition process. The films produced at the substrate temperatures of 750 to 950°C have been characterized by SEM, AFM, Raman and photoluminescence (PL) spectroscopy to assess the effect of Si doping on the diamond structure. The doped films showed bright photoluminescence of silicon-vacancy (SiV) color centers at 738 nm wavelength as well as noticeable side band at 723 nm. The optimum doping condition (SiH4/CH4 = 0.6%), that maximize the SiV PL emission, was determined for the range of silane concentrations SiH4/CH4 (0.0 – 0.9%) explored. A further PL enhancement can be achieved by increase in the substrate temperature. The applied in situ doping from gas phase is shown to be an easy and effective method to incorporate Si in diamond in a controllable way.

Effect of methyltrimethoxysilane impregnation on the cell wall porosity and water vapour sorption of archaeological waterlogged oak

This paper presents the water vapour sorption behaviour of degraded archaeological oak (Quercus robur L.) and the influence of methyltrimethoxysilane treatment on hygroscopicity. Wood samples (archaeological and undegraded recent oak) were treated with methyltrimethoxysilane using an oscillating pressure method. Moisture properties of the samples were determined using a dynamic vapour sorption system, and the surface area and porosity of treated and untreated waterlogged wood, previously dried using different methods, were characterised using a nitrogen sorption method. It was found that the silane modification resulted in a decrease in the equilibrium moisture content of archaeological oak samples from 23.7 to 19.4% for heartwood and from 23.3 to 10.0% for sapwood, respectively. After correction for silane content, however, the maximum equilibrium moisture content of the treated samples was 23.6% for heartwood and 21% for sapwood, which points rather at a bulking mechanism than chemical modification by silane. The results of the surface area and porosity measurements indicate that methyltrimethoxysilane is deposited in the cell wall and thus helps to preserve the microstructure of archaeological waterlogged wood.

FTIR Investigation of EVA Chemical Bonding Environment and Its Impact on Debond Energy

The chemical makeup of ethylene vinyl acetate (EVA) interfaces in photovoltaic (PV) modules is probed via Fourier-transform infrared spectroscopy (FTIR) to determine the impact of the EVA formulation on the adhesion degradation. EVA samples laminated with glass particles are used to demonstrate the effect of damp heat exposure on the glass-EVA interface, showing that increasing silane content increases chemical stability. Delamination interfaces created in one cell modules demonstrate a high correlation between the siloxane bonding at the silicon cell-EVA interface and the debond energy. A significant decrease in debond energy after UV exposure is also shown to be due in part to decreasing siloxane bond density at the interface. However, FTIR results indicated contributions to the adhesion beyond the chemical interface, and a basic tensile test indicates increasing bulk mechanical properties with increasing silane. These results demonstrate the importance of the EVA formulation on its adhesion performance and long-term reliability. Furthermore, it is shown that FTIR is a capable technique for assessing and quantifying chemical mechanisms within PV modules. These results can then be used to more effectively model module lifetimes and to better design polymer systems for PV modules.

Rapid, ultraviolet-induced, reversibly switchable wettability of superhydrophobic/superhydrophilic surfaces.

Controllable wettability is important for a wide range of applications, including intelligent switching, self-cleaning and oil/water separation. In this work, rapid switching and extreme wettability changes upon ultraviolet (UV) illumination were investigated. TiO2 nanoparticles were modified in solutions of trimethoxy(alkyl)silane, and the suspensions were sprayed on glass substrates. For such samples, the water contact angle (WCA) was shown to transition from a superhydrophobic (WCA ≈ 165°) to a superhydrophilic (WCA ≈ 0°) state within 10 min upon UV illumination and subsequent recovery to superhydrophobicity occurred after heat treatment. It was found that the changes in the trimethoxy(alkyl)silane upon UV illumination can explain the rapid decrease of the WCA from more than 165° to almost 0°. To further investigate the wettability transition, trimethoxy(alkyl)silane and Al2O3 nanoparticles (which are not photocatalytic) were mixed and spray-coated onto the glass substrates as the control samples. Then the unrecoverable change of trimethoxy(alkyl)silane under UV illumination can be confirmed. It was found that the presence of trimethoxy(alkyl)silane in the TiO2–trimethoxy(alkyl)silane coating served to speed up the super-wettability transition time from superhydrophobicity to superhydrophilicity, but also limited the number of wettability recycle times. With this understanding, the effect of the trimethoxy(alkyl)silane concentration on the number of recycle cycles was investigated.