Silane Coupling Research Articles

Study on surface grafting of hydroxyapatite and its influence on the properties of urea-formaldehyde resin

Urea formaldehyde (UF) is the most widely used resin in the wood composite board industry. UF has formaldehyde emission, which is harmful to the environment and human health. In this paper, hydroxyapatite (HAP) was surface modified by silane coupling agent (HAP-KH). And hydroxyapatite/urea formaldehyde resin (HAP-UF) was prepared by adding different amounts of HAP-KH. The optimal amount of HAP-KH was determined by wet shear strength and formaldehyde release. The degradation performance and degradation kinetics of the resin were also studied. The results show that the addition of HAP-KH can improve the wet shear strength of plywood and reduce the release of formaldehyde. The optimal content of HAP-KH was 3%, and the formaldehyde emission of plywood reached the lowest level of 0.35 mg L−1, 52.32% lower than that of the control resin. The wet shear strength was 1.14 MPa, 14.4% higher than that of the control resin. HAP-KH had no significant effect on the thermal stability of UF resins. However, HAP-KH has a significant effect on the thermal degradation mechanism of UF resins. The most likely kinetics mechanism models for UF and HAP-UF are G(a) = [−ln(1−α)]2 and G(a) = [−ln(1−α)]3, respectively.

Impact of graphene nanosheets on adhesion and corrosion performance of reinforced polyurethane coating for aerospace aluminium alloy 2024-T3

This investigation aims to create an integrated multilayer coating system for the surface of aerospace aluminium alloy 2024-T3. A solution-sonication mixing approach was applied to fabricate low-cost and high-efficiency layers. The coating system consisted of three main layers: pretreatment, green epoxy primer (GEP), and polyurethane (PU) top coating layer. To create the pretreatment layer, 50% graphene oxide (GOLMdis) was functionalized using a 50% 3-aminopropyltriethoxy silane coupling agent (SCA). The PU top coating layer was grafted with 1–3% wt. of GOLMdis to improve its resistance to environmental influences. Various analytical techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and Thermogravimetric analysis (TGA) were used to evaluate the properties of the PU-GO layer. The results confirmed the graft of GOLMdis onto the surface of PU, proving the existence of an interaction between the nanosheets and the polymer. The corrosion resistance performance of the multilayer coating systems was evaluated using electrochemical and adhesion tests. The 50%GO-SCA/Epoxy/2%GO-PU coating system outperforms other coating systems. It exhibited a significant improvement in the real impendence (Zre) by up to 9068 % compared to other coating systems. Moreover, only 5% of the coating was removed during the adhesion analysis. The results confirm the successful incorporation of anti-corrosion graphene oxide fillers into the multilayer coating system for corrosion protection of aerospace alloy 2024-T3.

Effect of holmium oxide nanoparticle on the mechanical properties of epoxy resin composites

In this study, holmium oxide/epoxy resin (Ho2O3/EP) nanocomposites were prepared by using different additions of Ho2O3 nanoparticles as nanofiller. The surface-modification treatment of Ho2O3 was applied with a silane coupling agent (SCA) to improve the interfacial combination between Ho2O3 and EP. The effect of SCA treatment on the chemical structure of Ho2O3 was investigated using Fourier transform infrared spectroscopy (FTIR). The effects of Ho2O3 nanoparticle and SCA treatment on the mechanical properties of the nanocomposites were studied. The fracture morphology of the EP nanocomposites was observed by scanning electron microscopy (SEM) to explore the failure mechanism of the EP nanocomposites with Ho2O3 nanoparticle. The experimental results show the tensile and flexural strengths of the nanocomposites are improved when Ho2O3 content is 1 wt. %. The tensile and flexural strengths were increased to 73.42 MPa and 130.85 MPa, respectively. But on further increase in Ho2O3 content of 1.5 wt. %, the tensile and flexural strengths were reduced. The SCA treatment could increase the interfacial bonding by containing C-H and Si-O functional groups, promoting the tensile properties, flexural properties, impact toughness, and fracture properties of the nanocomposites.

Preparation of low‐rolling resistance natural rubber composites from pyrolysis carbon black by plasma treatment

AbstractIn this study, the surface of pyrolysis carbon black (CBp) is modified by integrating the ball milling process with plasma treatment. High‐energy mechanical ball milling enabled more uniform contact and sufficient reaction temperature for the silane coupling agent and CBp. In addition, the impact of plasma activated the ash and surface deposits of CBp, reducing its inertness. Herein, the filler dispersion grade, Payne effect, vulcanization characteristics, and mechanical and dynamic mechanical properties are investigated by considering modified CBp/natural rubber (NR) composites. The ball milling plasma process can reduce the polarity of CBp. Compared with untreated CBp/NR composites, the plasma‐treated SCA‐CBp/NR composites exhibited increased CBp dispersion grades, higher processing safety, better processing fluidity, and improved mechanical properties. The reduced Payne effect ensured more filler‐rubber network structure, resulting in a reduction in rolling resistance.HighlightsThe coupling agent and CBp are treated by low‐temperature plasma and ball milling.The process promotes the formation of the filler‐rubber network.The dispersion grade of composites increased by 26.29%.The tensile strength increased by 5.57%, and the rolling resistance decreased by 19.44%.

Effect of the surface coating of carbonyl iron particles on the dispersion stability of magnetorheological fluid

The dispersion stability of carbonyl iron particle (CIP)-based magnetorheological fluid (MRF) is improved by CIP, which particle is etched with hydrochloric acid (HCl) to form porous structure with many hydroxyl groups and subsequently coated with silane coupling agents that have varying chain lengths. The microstructures, coating effect and magnetism of the CIPs were examined using the Scanning Electron Microscopy, Automatic Surface and Porosity Analyzer (BET), Fourier-Transform Infrared Spectroscopy, Thermogravimetric Analysis and Vibrating Sample Magnetometer. Furthermore, the rheological properties and dispersion stability of the MRFs were assessed using a Rotating Rheometer and Turbiscan-lab. The results revealed that the nanoporous structure appeared on the CIPs and the specific surface area increased remarkably after being etched by hydrochloric acid. Additionally, as the chain length of the silane coupling agent increases, the coated mass on the particles increases, the the density and the saturation magnetization of particles decreased, and the coated particles with different shell thicknesses were obtained; without a magnetic field, the viscosity of MRF prepared by coated particles increase slightly, due to the enhancement of special three-dimensional network structure; under a magnetic field, the viscosity of the MRF decreased distinctly; the sedimentation rate of MRF decreased from 58 to 3.5% after 100 days of sedimentation, and the migration distances of the MRFs were 22.4, 3.7, 2.4, and 0 mm, with particle sedimentation rates of 0.149, 0.019, 0.017, and 0 mm/h, respectively. The MRF with high dispersion stability was obtained, and the etching of CIP by HCl and the proper chain length of the coating of silane coupling agent were proved effective manners to improve the dispersion stability of MRF.

Functionalized boron nitride nanosheets and their polypropylene nanocomposites: influence on thermal, mechanical, rheological and wear behaviour

ABSTRACT The few-layer hexagonal boron nitride (hBN) nanosheets with hydroxyl (−OH) functional group at edges are synthesized using heat treatment of micron size hBN powder followed by sonication. These nanosheets are modified with a silane coupling agent, 3-Aminopropyl,triethoxysilane (APTES). The synthesized hBN nanosheets are mixed with the PP matrix using twin-screw extrusion followed by injection moulding. In case of APTES-modified hBN nanosheets incorporation in the PP matrix with PP-grafted maleic anhydride (PP-g-MA) shows the formation of an imide bond between the MA functional group of PP-g-MA and the amine group of APTES modified hBN nanosheets revealing compatibilization. The flow behaviour index values are lower for hBN nanosheets filled PP nanocomposites showing the improved processability from Rheological characterization. The few-layered – OH and APTES modified hBN nanosheet incorporation in the PP matrix improves the tensile and thermal properties. The incorporation of APTES modified hBN nanosheet in the PP matrix shows an increase in tensile modulus (18.1%) and tensile strength (8.1%) respectively. Wear studies show the incorporation of – OH and APTES modified hBN nanosheets in the PP matrix decreases the coefficient of friction and wear rate significantly. The wear rate at 4 min of wear testing for modified hBN nanosheet in the PP nanocomposites is ~ 96% less in comparison with neat PP. The wear mechanism is established from wear measurements and scanning electron microscopy (SEM) of worn-out wear surfaces of PP nanocomposites.

Insight into the relationship between interfacial structure and thermal conductivity in epoxy resin/Al2O3 composite

AbstractThe relationship between interfacial structure and thermal conductivity in epoxy resin/Al2O3 composite is important but is still elusive. Here, we illuminate this issue by investigating the role of four silane coupling agents in thermal conductivity for epoxy resin/Al2O3 composites. The results show that 3‐glycidoxypropyltrimethoxysilane (KH560) is the best silane coupling agent to modify Al2O3, resulting in the lowest viscosity and the highest thermal conductivity of the epoxy resin/Al2O3‐KH560 composite compared with alternative systems. This is attributed to the strong interfacial interaction between Al2O3‐KH560 and epoxy resin, as confirmed by the Fowkes model and broadband dielectric spectroscopy. The interfacial thermal resistance between the epoxy resin and Al2O3 is also quantitatively measured via a photothermal radiometry technique. The epoxy resin/Al2O3‐KH560 also has the lowest interfacial thermal resistance (1.50 ± 0.02 × 10−6 m2 K W−1), compared with the other three systems. This study advances the understanding of the relationship between interfacial structure and thermal conductivity in polymer composites.Highlights The relationship between interfacial structure and thermal conductivity in epoxy resin/Al2O3 composite is understood. The interfacial structure is characterized by broadband dielectric spectroscopy. The interfacial thermal resistance is quantitatively measured via a photothermal radiometry technique.

Interpenetration of Rubber and Silane Coupling Agent on an Inorganic Substrate Revealed by Spin-Contrast-Variation Neutron Reflectivity

Interpenetration of Rubber and Silane Coupling Agent on an Inorganic Substrate Revealed by Spin-Contrast-Variation Neutron Reflectivity

The influence of doping with different surface modified SiO2 nanoparticles on the dielectric properties of natural ester insulating oil

Nanoparticles are presently considered to be high-potential filler materials in insulation medium. Surface-modified nanoparticles can not only improve the compatibility between nanoparticles and insulation liquid but also enhance the dielectric properties. Herein, models of soybean oil-based natural ester insulation oil doped with two silane coupling agents (A151, KH550) modified SiO2 were established, respectively. Molecular dynamics and DFT first principles were applied to explore the effect of two nanoparticles on the dielectric properties of liquid-insulation medium. The results showed that two types of nanoparticles can restrict the diffusion of water molecules by forming hydrogen bonds, while the number of hydrogen bonds in KH550–SiO2 is one-third more than that in A151-SiO2, and the interaction energy is lower, demonstrating a stronger adsorption effect on water molecules. Moreover, surface electrostatic potential and frontier molecular orbitals showed that KH550–SiO2 have a higher adsorption on charged particles in natural ester insulation oil, which can further inhibit the development of streamer discharge in the liquid insulation medium, improve its dielectric property and delay the aging and deterioration of natural ester insulation oil. This study extends our knowledge into the influence of silane coupling agents modified SiO2 nanoparticles on the dielectric performance of liquid insulation materials from a microscopic perspective.

Optimizing the performance of TPCB/SCA composite-modified asphalt using improved response surface methodology

Abstract A composite-modified asphalt was developed by incorporating tire pyrolytic carbon black (TPCB) with a silane coupling agent (SCA) to enhance its ductility and storage stability. The functional binding between asphalt and TPCB was improved by the addition of SCA. The gray correlation comprehensive evaluation method is incorporated into the response surface methodology (RSM), leading to an improved RSM. The improved RSM was employed to optimize the content of the modifier and the preparation process to enhance overall performance. A central composite design-based experiment was conducted to optimize the penetration, softening point, 10°C ductility, Brookfield rotational viscosity, and storage stability indicators of modified asphalt. The response surface of the gray comprehensive evaluation value of the evaluation indicators was calculated using the gray correlation analysis method, and a second-order regression model was established between independent variables such as TPCB, SCA content, and shear time factor and the gray comprehensive evaluation value. This model analyzed the impact of a single variable and variable interaction on the performance of the TPCB/SCA composite-modified asphalt. The optimized model results showed that the preparation parameters that optimize the expected comprehensive performance of the composite-modified asphalt are 9.2% TPCB content, 2.1% SCA content, and a shear time of 56.3 min. Finally, the TPCB/SCA composite-modified asphalt prepared with the improved RSM exhibited the highest gray comprehensive evaluation value and the best overall performance, indicating the feasibility of the optimized preparation parameters with the improved RSM.

Spearheading a new era in complex colloid synthesis with TPM and other silanes.

Colloid science has recently grown substantially owing to the innovative use of silane coupling agents (SCAs), especially 3-trimethoxysilylpropyl methacrylate(TPM). SCAs were previously used mainly as modifying agents, but their ability to form droplets and condense onto pre-existing structures has enabled their use as a versatile and powerful tool to create novel anisotropic colloids with increasing complexity. In this Review, we highlight the advances in complex colloid synthesis facilitated by the use of TPM and show how this has driven remarkable new applications. The focus is on TPM as the current state-of-the-art in colloid science, but we also discuss other silanes and their potential to make an impact. We outline the remarkable properties of TPM colloids and their synthesis strategies, and discuss areas of soft matter science that have benefited from TPM and other SCAs.

Improving the Corrosion Resistance of Micro-Arc Oxidization Film on AZ91D Mg Alloy through Silanization

The presence of inherent micro-pores and micro-cracks in the micro-arc oxidation (MAO) film of Mg alloys is a key factor contributing to substrate corrosion. A composite film layer with high corrosion resistance was achieved through silanizing the micro-arc oxidation film. The corrosion performance of the MAO films treated with various silane coupling agents was assessed through morphological characterization and electrochemical tests. SEM graphs depicted that the silane film can effectively seal the defects existing in micro-arc oxidation film, and electrochemical tests indicated the significant corrosion resistance improvement of MAO film after silanization treatment.

Study of Mechanical and Surface Properties of Multi-Walled Carbon Nanotube Grafted Flax Fiber and Its Composites

ABSTRACT The modification method of grafting multi-walled carbon nanotubes (MWCNT, abbreviated as CNT in this paper) on the surface of flax fibers was investigated, i.e. CNT were grafted onto the surface of flax fibers by silane coupling agent under the action of ultrasonic waves to form covalent bonding. The tensile strength of CNT grafted flax fiber is 22% higher than that of untreated flax fiber monofilament. The tensile strength of FFRP composites after CNT grafting treatment increased by 14.2%; however, the tensile modulus of single fiber and composites did not show a significant increase, the interfacial shear strength of the fiber-resin is 38.3% higher than that of untreated filament. The improvement of the contact angle after grafting was investigated by observing the surface morphology, and the surface of flax filament was characterized by scanning electron microscopy and atomic force microscopy. Also the elemental changes of the flax single fiber surface before and after the treatment were analyzed using X-ray photoelectron spectroscopy. The results showed that the tensile strength of flax single fibers, its composites, and interfacial shear strength of fiber-matrix was improved after CNT grafting treatment but the increase of modulus was not obvious.

Surface modified molybdenum disulfide nanosheets for corrosion resistance improvement on polyurethane coatings

Abstract Organic–inorganic hybrid coating has been applied on metallic corrosion protection effectively. Molybdenum disulfide (MoS2) nanosheets with graphene-like two-dimensional lamellar structure were an anticorrosion inorganic additive, rendering the organic coating better corrosion resistant. However, the aggregation and poor solubility are still current issues that should be addressed. Functionalization MoS2 nanosheets with surface modified by polydopamine (PDA) and silane coupling agent (KH560) were prepared in polyurethane (PU) composite coatings to obtain dense and intact multilayer network structure coatings for corrosion protection. KH560-PDA-MoS2/PU coating with crosslinked polymer network structure has a high impedance modulus, large contact angle, and strong hydrophobicity. The coating meets the national technical standards for salt spray testing and nitric acid (HNO3) titration testing, demonstrating excellent corrosion resistance.

Antibacterial MXene composite with excellent U/V selectivity for uranium extraction

Uranium, as a radioactive element, is the source of utilizable energy for mankind in the future. Large quantities of uranium resources are contained in seawater, so uranium extraction from seawater is undoubtedly the most feasible method. However, the presence of competitive ions such as vanadium hinders the efficient extraction of uranium, which is currently a challenge that needs to be solved. Here, silane coupling agent (KH550) was grafted onto two-dimensional metal carbide (MXene). Subsequently, salicylaldoxime (SA) was deposited onto MXene particles using self-polymerization of dopamine (DA) to prepare PDA/SA deposited MXene composite grafted with KH550 (PDA/SA/MXene-KH550). The adsorbent exhibited excellent selectivity for uranium ions with a uranium/vanadium selectivity ratio of 4.8. In antibacterial experiments, the PDA/SA/MXene-KH550 composite showed excellent antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), demonstrating the ability to adapt to complex marine microbial contamination. In addition, the maximum experimental uranium adsorption capacity of the composite was 332.3 mg/g, following the pseudo-second-order kinetic model and the Langmuir isotherm model. After five adsorption-desorption cycles, the elution efficiency of PDA/SA/MXene-KH550 for uranium can still reach 74.7 %, which demonstrated that the adsorbent had superior stability and regeneration ability, providing the possibility for actual enrichment of uranium.

Multiscale enhancement of carbon/carbon composite performance by self-assembly of sulfonated graphene with silane-treated carbon fibers

The application prospects of carbon/carbon composites are greatly limited by interfacial cracks and pores caused by binder pitch displacement and cracking during high-temperature carbonization. In this study, silane coupling agent was coated on the surface of oxygen plasma-treated carbon fibers (CFs) and subsequently electrostatically self-assembled with sulfonated graphene (SG) to improve the interfacial bonding between filler and CTP. The results indicate that the tensile strength of carbon fiber treated with silane coupling agent increased by 19 % compared to untreated CF. This increase in strength may be related to the layer of silane coupling agent that repaired the grooves and imperfections on the CF surface. The addition of SG not only improves the distribution characteristics of the fibers, allowing the silane-treated CF to play a greater role in the matrix, but also creates a three-dimensional hydrogen-bonded cross-linking between the SG and the coal tar pitch (CTP) on the surface of the fibers. This inhibits CTP displacement and pyrolysis, achieving a tight bonding of the fiber to the matrix. The composites' structural integrity and mechanical properties were significantly improved due to the synergistic effect of silane-treated CF and SG. The compressive strength was 216.98 MPa, with a flexural strength of 54.78 MPa, 250 % higher than the untreated carbon fiber-reinforced composites. Additionally, the porosity decreased by 31.5 %, and the antioxidant properties increased. The study presents a potential solution to improve the performance of carbon/carbon composites by using the silane-treated CF-SG multiscale reinforced phase.

Preparation and performance of carboxyl modified NdFeB and derived magnetic self-healing PU composites

With the rapid development of today’s society, magnetic self-healing materials are widely used in many fields due to their excellent magnetism and self-healing ability. This article presents a magnetic self-healing composite with good mechanical, self-healing and magnetic properties and magnetic drive performance. Tetraethyl orthosilicate (TEOS), silane coupling agent and succinic anhydride (SA) were used for surface modification of NdFeB magnetic particles (MPs) and NdFeB@SiO2-COOH MPs was synthesized. Iron(III) ions were added to the self-polymerization process of the natural small molecule thioctic acid (TA) to form the PTA-Fe prepolymer. PTA-Fe prepolymer, isophorone diisocyanate (IPDI) and polyether amine (PEA) reacted to synthesis PTA-Fe-PU matrix with good self-healing performance at room temperature. The prepared NdFeB@SiO2-COOH MPs was mixed with the self-healing matrix and cured to obtain the magnetic room-temperature self-healing composite MPTA-Fe-PU. The best tensile strength of the composite was 7.31 MPa and the ultimate elongation was 833 %. After the prepared MPTA-Fe-PU sample strip was completely cut, the incision on the surface almost disapeared and the tensile strength recovered to 6.35 MPa after 12 h self-healing at room temperature. The self-healing efficiency was up to 87 %. The highly efficient self-healing properties were mainly derived from the disulfide bonds exchange reaction and iron(III) ion coordination in the matrix.

Effect of nano-silica modified resin on the interface strength and toughness of Al/CFRP hybrid laminates

In order to improve the interfacial strength and toughness of aluminum alloys and CFRP (carbon fiber reinforced plastics) hybrid laminates, modified resin with lower porosity was prepared by adding nano silica treated with silane coupling agent into epoxy resin. Al/CFRP hybrid laminates with modified resin were prepared by physical liquid deposition method and hot-press process. The strength and toughness of Al/CFRP hybrid laminates with modified resin were evaluated by tensile shear test and end notch fracture (ENF) test. The experimental results showed that the interfacial shear strength of Al/CFRP hybrid modified resin laminates is 18.8 ± 0.8 MPa and the fracture energy is 1546.33 ± 10.26 J /m2, which is 28.76 % and 15.38 % higher than that of Al/CFRP hybrid laminates with raw resin, respectively. The well-dispersed silicon nanoparticles effectively mitigate internal stress during the cross-linking process of the modified resin, thereby diminishing the dimensions of microcracks within the modified resin. The transition layer of the modified resin interface formed a cooperative and smooth structure. This structure can ensure that the transition of elements in the interface layer is smooth, and it is not easy to cause stress concentration. The formation of new bonds (C-Si bonds) at the interface of the modified resin indicates an enhancement of bonding strength at the interface, superimposing upon van der Waals forces, thereby enhancing the adhesive strength of the modified resin interface.

Fabrication of cement-based superhydrophobic coatings with enhanced self-cleaning property, chemical stability, and UV-radiation resistance

Superhydrophobic coatings (SCs) can potentially reduce dust accumulation on the structure surfaces and mitigate environmental corrosion.In this study, a superhydrophobic coating composed of nano-SiO2, N-octyltriethoxysilane, and silane coupling agent was prepared for cement-based structures by green sol–gel method. By means of SEM, FTIR, XRD, EDS, and XPS, it was proved that cement-based superhydrophobic coatings were successfully formed on the surface of cement-based substrate. Two different techniques (brushing and replication) were used for fabricating cement-based superhydrophobic coatings (CBSCs), and their optimum preparation conditions were determined via orthogonal experiments. The obtained results revealed that the contact angle (CA) and sliding angle (SA) of the fabricated SCs reached 153° and 4°, respectively. Furthermore, the CBSCs exhibited outstanding self-cleaning properties and mechanical stability. Moreover, the chemical stability and UV-radiation resistance of the fabricated CBSCs were significantly improved compared with ordinary concrete.

Adsorption behaviors of ethyltriethoxysilane on the calcium silicate hydrate surface: Effect of Ca/Si ratio and adsorption sites

Silane coupling agents (SCAs) are utilized to enhance the impermeability of concrete surfaces, whose adhesion force is affected by the interfacial interactions in between that remain unclear. In this study, we probe the adsorption tendencies of ethyltriethoxysilane (ETES) onto C-S-H surfaces by employing density functional theory (DFT) calculations and Born-Oppenheimer molecular dynamics (BOMD) simulations. Results suggest that significant chemisorption occurs at the CaOH(1.5), SiOH(1.0), Ca(1.0) sites C-S-H surfaces. Electronic structures analysis proved that the chemisorption of hydroxyl sites arises from the overlap of H and O atomic orbitals, resulting in the formation of hydrogen bonds. The chemisorption of the Ca(1.0) site is caused by electrostatic adsorption between calcium and oxygen. Adsorption energy results show: ECaOH(1.5) > ECa(1.0) > ESiOH(1.0). Moreover, ETES remains transverse adsorption on low Ca/Si C-S-H surfaces, while displaying longitudinal adsorption on high. Interaction analysis illustrates the configuration discrepancy arising from the absence of bridge silicon-oxygen tetrahedrons which possess vdW interactions with ethyl. Notably, transverse adsorption covers a wider area on the C-S-H surface thereby enhancing the hydrophobic effect. In summary, the utilization of ETES presents notable advantages within the context of low Ca/Si ratio cement. This study contributes valuable insights into the design and application of silane coatings.