Coupling Agent Research Articles

Unlocking Heavy Metal Remediation Potential: A Review of Cellulose–Silica Composites

This comprehensive review explores recent advancements in heavy metal remediation techniques, focusing on the utilization of cellulose–silica composites and tailored surface modification techniques. We examine the synthesis strategies and properties of cellulose–silica adsorbents, highlighting their enhanced adsorption capacities and structural robustness for removing heavy metal pollutants from aqueous environments. The review investigates various surface modification approaches, including thiol functionalization, amino acid grafting, and silane coupling agents, for optimizing the surface chemistry and morphology of cellulose–silica composites. Mechanistic insights into the adsorption processes and kinetics of modified adsorbents are discussed, along with considerations for optimizing adsorption performance under different environmental conditions. This review provides valuable perspectives on the development of effective adsorbent materials for sustainable heavy metal remediation applications.

Interfacial control and dispersion characteristics of polylactic acid fiber/pulp fiber composites

AbstractTo solve the problem of the dispersibility of pulp fiber in polylactic acid (PLA)/pulp fiber composites, PLA fiber instead of PLA beads and pulp fiber were used for initial physical mixing, and then internal mixer‐melting was conducted. The dispersion of pulp fiber in PLA was improved compared with conventional composite preparation protocols. After the pulp fiber was treated with a silane coupling agent, the compatibility of the composite and the transparency of the material were also improved. When the pulp fiber content reached 30%, the mechanical properties and heat resistance of the composite were optimal: tensile fracture strength of 56.52 MPa, and thermal deformation temperature increase of 5°C. Rheological studies indicate that when the pulp fiber content reached 10%, the system exhibited a PLA‐pulp fiber network. When the pulp fiber content was ≥20%, the system exhibited a PLA–PLA and pulp fiber–pulp fiber dual‐network structure.Highlights The dispersion of filler in the matrix was improved by blending fiber with fiber. There was rheological percolation upon filling the pulp fiber in the PLA matrix. The coupling agent facilitated reactive compatibilization and PLA chain extension.

Influence of Interface Modification on the Moisture Absorption and Thermal Resistance of Ramie Fiber/Degradable Epoxy Composites

Natural fiber/degradable epoxy composites have received much attention for their advantages of low carbon emissions, low environmental pollution, and utilization of renewable resources. However, the poor interfacial bonding strength and inferior moisture resistance of natural fiber/degradable epoxy composites restrict their application areas. In order to improve the moisture and heat resistance of natural fiber/degradable epoxy resin-based composites, this study modified the surfaces of ramie fibers with hydroxylated carbon nanotubes, silane coupling agents, and sodium hydroxide, respectively. Three types of modified ramie fiber/degradable epoxy composites, namely F-CN-DEP, F-Si-DEP, and F-OH-DEP, were prepared using a winding forming process. The water absorption rate and short-beam shear strength of the materials were tested under different environments, and the fiber morphology and thermal–mechanical properties of the materials were investigated by scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). The results show that F-CN-DEP exhibited the lowest moisture absorption rate; the highest shear strength, of 43.8 MPa; and a glass transition temperature (Tg) of 121.7 °C. The results demonstrate that carbon nanotubes on the fiber surface can improve the interfacial stability of ramie fiber/degradable epoxy composites in humid and hot environments. These results give guidelines for the development of natural fiber/degradable epoxy composites.

Demonstration of π-π Stacking at Interfaces: Synthesis of an Indole-Modified Monodisperse Silica Microsphere SiO2@IN.

In the present study, a novel silane coupling agent, designated INSi, was synthesized via a facile synthetic route, incorporating indole-functional moieties. This agent was further employed for the surface modification of homemade silica nanomicrospheres (SMPs). The ensuing nanomicrosphere composite, denoted as SiO2@IN, exemplified pronounced interfacial π-π interactions. Optimization of the reaction conditions was conducted using the response surface optimization technique. Subsequent validation of interfacial π-π interactions was accomplished through a synergistic approach, integrating theoretical calculations and comprehensive analyses of spectral and morphological attributes exhibited by the SiO2@IN.

Rubber-glass nanocomposites fabricated using mixed emulsions

Many composites consist of matrices of elastomers and nanoparticles of stiff materials. Such composites often have superior properties and are widely used. Embedding elastomers with nanoparticles commonly necessitates intense shear, using machines like extruders and roll millers, which cut polymer chains and degrade properties. Here, we prepare a rubber-glass nanocomposite by using two aqueous emulsions. Each emulsion is separately prepared with a single species of polymer chains. Each polymer chain is copolymerized with a small amount of silane coupling agent. Upon mixing the two emulsions, as water evaporates, the glassy particles retain the shape, and the rubbery particles change shape to form a continuous matrix. Subsequently, the silane coupling agent condensates, which cross-links the rubbery chains and interlinks the rubbery chains to the glassy particles. The cross-links and interlinks stabilize the nanostructure and lead to superior properties. The nanocomposite simultaneously achieves high modulus (~30 MPa), high toughness (~100 kJ m-2), and high fatigue threshold (~1,000 J m-2). The method of mixed emulsion is environmentally friendly and compatible with various open-air manufacturing processes, such as coat, cast, spray, print, and brush. Additionally, the silane coupling agent can interlink the nanocomposite to other materials. The method of mixed emulsion can be used to fabricate objects of complex shapes, fine features, and prescribed spatial variations of compositions.

Minimizing usage of silane coupling agent for amine-grafted mesoporous silica CO2 adsorbent

AbstractAmine-grafted adsorbents are promising CO2 adsorbents; however, the excessive addition of an amino silane coupling agent during their synthesis increases their production cost. Thus, using low amounts of silane, we synthesized 3-aminopropyltrimethoxysilane (APTMS)-grafted SBA-15 mesoporous silica and evaluated its CO2 adsorption performance. APTMS-grafted SBA-15 samples were prepared using either impregnation or heating–filtration method (grafting). The obtained samples were characterized by X-ray diffraction spectroscopy, transmission electron microscopy, N2 adsorption/desorption, scanning electron microscopy, magic-angle spinning nuclear magnetic resonance, and elemental analysis. The results revealed that the micropores of SBA-15 were preferentially blocked, and APTMS increasingly occupied the mesopores with increasing amine loading. The CO2-adsorption performance of the adsorbents was measured by thermogravimetric analysis under dry conditions. Both synthesis methods achieved high amine immobilization efficiency (78.3–92.2%), as estimated from the amount of silane coupling agents used in the synthesis and that immobilized on the support. The adsorbents prepared by the two methods adsorbed similar amounts of CO2 of approximately 0.5 mmol g− 1 in 400 ppm CO2 and ~ 1.0 mmol g− 1 in 5 vol% CO2. The adsorption amounts attained in this study are comparable to those of previously reported silane-coupling-agent-modified adsorbents that were prepared with more silane. In contrast, the adsorption rate of the samples was affected by the synthesis method, even with similar amine loadings. Nonetheless, the results revealed that even with a low amount of the silane coupling agent, high-performance amine-grafted CO2 adsorbents could be synthesized.

Synergistic flame‐retardant effects between silane coupling agents modified expanded graphite and Pt catalyst in silicone rubber composites

AbstractIn this work, different kinds of silane coupling agents modified expanded graphite (MEG) fillers were successfully prepared and then incorporated into silicon rubber matrix to fabricate flame‐retardant composite materials (SR/MEG). The inserted MEG fillers with siloxane chains exhibited good compatibility with the silicon rubber matrix, which cannot only reduce the negative impact of adding fillers on mechanical properties but also endow the silicon rubber composites with ideal flame retardancy. Subsequently, platinum (Pt) catalyst was incorporated into the SR/MEG composites to prepare SR/MEG/Pt composites, and the synergistic effects of MEG and Pt catalyst on the thermal stability, flame retardancy, and combustion behavior of silicon rubber composites were systematically investigated. The target SR/MEG/Pt composite with appropriate addition of MEG and Pt catalyst can obtain relatively high char residue of 41.9% and limiting oxygen index value of 29.6%, as well as achieve V‐0 rating in the vertical combustion test, owing to the formation of expanded and dense silicon–carbon protective layer under the catalysis of Pt catalyst. Moreover, the cone calorimeter test results showed that the peak of heat release rate and total heat release of SR/MEG composites were further reduced after the addition of an appropriate amount of Pt catalyst, manifesting the good synergistic effect of MEG and Pt catalyst on the flame retardancy performance of silicon rubber. The method proposed herein may provide a promising way for fabricating high‐performance flame‐retardant silicone rubber materials.

Combustion performance of aluminum modified boron nanoparticles coated with silane coupling agent

Boron (B) powder, with its high mass and volumetric heat values, makes it highly promising in the field of energetic materials. However, the oxide layer on the B surface is the most significant barrier to realizing its full potential as a fuel. How to eliminate or disrupt the oxide layer is currently an urgent problem that needs to be addressed. This study proposes an approach to enhance the combustion of nano-B powder by coating aluminum (Al) onto its surface using a silane coupling agent. The combustion characteristics of Al-modified B powder with different Al contents were investigated through experimental and molecular dynamic simulation methods, and the bidirectional diffusion mechanism on the interfacial layer of modified B particles was revealed. A small amount of Al powder can largely lower the initial oxidation temperature of B powder, increase the maximum flame temperature, and enhance the heat release. However, an excessive amount of Al powder leads to a deterioration in the combustion of B powder but can alter the combustion behavior and suppress the aggregation of B powder during the combustion. Additionally, combination reaction and redox reaction occurring during the combustion of B@Al samples not only reduce the burning time of B powder but also accelerate the flame expansion speed and improve the combustion efficiency. These results lay the foundation for the application of B@Al in the field of energetic materials.

The effect of gamma rays and stearic acid on calcium carbonate and its impact on the properties of epoxy-based composites

Abstract The purpose of this research is to produce composites of epoxy resin and calcium carbonate (EP/CaCO3) and investigate how treating the CaCO3 filler with stearic acid and gamma radiation affects the properties of the epoxy composites, enhancing their suitability for a range of applications. The CaCO3 powder was subjected to stearic acid treatment and later exposed to γ-radiation at various doses namely (10, 20 and 30 kGy), Different weight percentages of untreated and treated CaCO3 powder were added to epoxy resin (EP) to create EP/CaCO3 composites loaded with varying amounts of CaCO3 filler (5 %, 10 %, 20 %, 30 %, and 40 %). The influence of both stearic acid treatment and different doses of gamma radiation on CaCO3 was investigated. The composites were subjected to characterization of various properties including mechanical (splitting tensile strength, impact strength), thermal (TGA and dimensional thermal analysis) as well as morphological SEM examination. The analysis’ findings demonstrated that the stearic acid monolayer functions as a coupling agent in the EP matrix and can coat CaCO3 particles efficiently. The modification of CaCO3 by stearic acid and exposure to 30 kGy of gamma radiation shows a notable improvement in thermal stability and mechanical qualities for the epoxy composites loaded with various CaCO3 concentrations.

Effect of Ex Situ Modification of Bacterial Cellulose with Organosilane Coupling Agent on Drug Delivery Properties

Effect of Ex Situ Modification of Bacterial Cellulose with Organosilane Coupling Agent on Drug Delivery Properties

Effect of filler surface treatment on the physico-mechanical properties of filler/styrene-butadiene rubber nanocomposites

In the present work, the effects of various filler types and content on the characteristics and properties of styrene-butadiene rubber (SBR) were studied. This study prepared SBR filled with different fillers: kaolin, metakaolinite, synthetic zeolite Na-A, alumina (Al2O3) nanoparticles, and hybrid filler (synthetic zeolite Na-A/Al2O3). The silane coupling agent 3-aminopropyltriethoxysilane (APTES) was employed to treat the surface with fillers. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to determine the surface morphology. The results demonstrated that fillers improved the physicomechanical properties. Tensile strength and elongation at break (%) in composites containing synthetic zeolite Na-A increased by up to 158.6% at 3 phr and 100% at 2 phr, respectively. The results showed that the surface properties displayed by SEM analysis indicated a good distribution of filler particles. Also, the rubber compound’s resistance to organic solvents such as toluene was improved, as evidenced by swelling properties; the swelling ratio decreased by 17.5% while the crosslink density increased by 42.6% at 5 phr Al2O3/synthetic zeolite Na-A. The constants of the various hyperelastic models that explain the behavior of the composite materials under study were determined, and their predictions of the experimentally obtained stress-strain curves were compared. The study’s experimental findings will be helpful for several industrial uses, including an extender in water-based paints, rubber fillers, ceramic materials, paper fillers, and coating pigments.

Polyurethane modified asphalt mixture incorporating waste glass with a wide size range: preparation and performance evaluation

Increasing the utilisation rate of waste glass in asphalt mixtures, especially that with a wide range of particle sizes, is of great importance to resource recycling, while it may bring drawbacks to the engineering performance of asphalt mixtures. Incorporating polyurethane (PU) as a modifier can enhance asphalt mixture's performance, but there is limited research considering the usage of waste glass as aggregates. In this study, PU modified asphalt mixtures were prepared, incorporating waste glass particles ranging in size from 2.36mm to 9.5mm as a portion of the aggregates. Optimal preparation methods and mix designs for the PU-modified asphalt binder were determined through a series of tests designed based on Orthogonal method. The performances of the PU-modified asphalt binders were then evaluated to guide the selection of the optimal preparation method and mix design. PU-modified waste glass asphalt mixtures were then prepared and their engineering performances were assessed at various glass-to-aggregate ratios. The results show that scheme PU-1 with a shearing temperature of 140°C, a shearing time of 10min, a PU content of 10% and a compatibiliser content of 2% is suggested for preparing the PU-modified asphalt binder, which shows the best performances due to superior chemical modification and compatibility. Higher glass content decreases the high/low-temperature performance, but it can be improved by adding silane coupling agent or hydrated lime, with the latter showing better results. The incorporation of glass particles has little impact on anti-sliding performance, and asphalt mixtures maintain excellent anti-sliding properties up to a 20% replacement rate. Overall, the performance of the asphalt with waste glass up to 15% can meet the specification requirements. This novel approach offers a potential solution to enhance the incorporation of waste materials in asphalt construction, contributing to sustainable and environmentally-friendly road infrastructure.

Multimode sensing and imaging platform for versatile detection of GSH based on surface modification strategy of Ru(bpy)32+ doped SiO2 nanoparticles

Multimode sensing and imaging platform for versatile detection of GSH based on surface modification strategy of Ru(bpy)32+ doped SiO2 nanoparticles

Enhanced Interfacial Bonding Strength of Hot-Pressed Titanium Alloy/CFRTP Joint Via Laser Ablation and Interfacial Adhesive

Joining titanium alloy with carbon fiber reinforced thermoplastic (CFRTP) is one of the hot subjects in the automotive and aerospace industries. To improve the joint strength of TC4/CFRTP PA6, this study combined the surface treatment of TC4 alloy, including laser ablation, Silane Coupling Agent (SCA) treatment, and interfacial PA6 adhesive. The results showed that the laser texturing induced the micro-scale porous and macro-scale groove grid structure, respectively. The superhydrophilicity of the laser texturing as well as amino polar groups induced by SCA treatment promoted the adhesion of the thermoplastic PA6 melt into the microstructure of the TC4 alloy surface. The mechanical interlocking and hydrogen bonding between TC4 alloy and CFRTP PA6 significantly improved the shear strength of the TC4/CFRTP PA6 joint (17.5 MPa). Furthermore, with the incorporation of interfacial PA6 adhesive, the joint strength was further enhanced, and the damage of the TC4/CFRTP PA6 joint was transformed from interfacial to interlaminar CFRTP PA6.

Preparation and fluorescence detection of nitrogen-doped carbon quantum dots/cotton fiber composites

From the perspective of environmental protection and sustainable development, fluorescent probes have been prepared using inexpensive raw materials for fluorescence detection in wastewater treatment. Nitrogen-doped carbon quantum dots (N-CQDs)/cotton fiber composites were prepared by grafting N-CQDs onto the oxidized cotton fibers using a silane coupling agents. Through a series of characterizations using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray energy dispersive spectrometry (EDS), it was found that N-CQDs were loaded onto cotton fibers. In the N-CQDs/cotton fiber composite, the fluorescence rate of carbon quantum dots is higher, which is 17.2 %, and the detection limit is 1.21 μM. The optimum conditions for fluorescence detection of azo dye Chrome black T(EBT) with pH 8 and concentration 10 μM were studied. This method for the detection of EBT has advantages such as high sensitivity, simplicity, speed, reusability, and a high potential for application in wastewater detection.

معجل ثالثي مستدام لفلكنة الكبريت لمطاطي ال NR و ال SBR من مستخلص اوراق شجرة

       تم تحضير معجل جديد, طبيعي, رخيص, ومتاح يستخدم في انظمة فلكنة المطاط الطبيعي NR)) و مطاط الستايرين بيوتادايين ((SBR وقد تم تحضير هذا المعجل من المخلفات الزراعية. حيث تم اضافة مسحوق مجفف لمستخلص من اوراق شجرة الكينوكاربس لانسيفوليوس Conocarpus lancifolius بالنسب المئوية التالية:                   0.5, 1.0, 1.5, 2.0) wt%) الى العجينة الرئيسية لمطاطي ال NR  و ال SBR  والتي تحتوي على معجلات البنزوثايوزول (MBT, MBTS). تم اختيار مستخلص CLLE)) نظرًا لاحتوائه على مركبات الفلافونويد, السابونين و الفينولات داخل هيكلها، مما يعزز الترابط الهيدروجيني (H-bond) كرابطة ثانوية ، والتي بدورها تعزز معدل المعالجة. اظهرت النتائج قابلية مستخلص CLLE)) على تعجيل  (curing systems)نظامي الفلكنة المذكورين حيث كان التركيز الامثل مع مطاط  ال  0.5( pphr) SBR  والتركيز الامثل لمطاط ال NR  1 (pphr) . وكان تأثير هذا المستخلص على نظام معالجة مطاط  NR اكبر من مطاط ال SBR حيث انخفض زمن الانضاج الامثل Tc90 لمطاط ال  SBR بمقدار (2.42 %) في حين انخفض بمقدار 17.74 % لمطاط ال NR  , اما بالنسبة لمؤشر معدل النضوج (CRI) فقد ازداد في مطاط ال SBR بمقدار 5.9 % فقط, في حين انه ازداد بمقدار 24.83 % لمطاط ال NR. بالإضافة الى ذلك فان اضافة مستخلص CLLE)) قد عملت على تقليل زمن الاحتراق (ts2) ولكلا المطاطين. وكانت قيم ال ts2 لعينات مطاط ال SBR اكبر من قيم ال ts2 لعينات مطاط ال NR. كما بينت النتائج ان اضافة CLLE)) لم تؤثر على قيم مقاومة الشد وكان هناك انخفاض طفيف في قيمة الصلابة وزيادة في معامل الاستطالة عند (300%) وزيادة في قيم الاجهاد و الانفعال قبل الفشل. أدت إضافة CLLE إلى زيادة معدلات المعالجة بسبب احتوائها على مكونات نشطة (الفلافونويد والسابونين والفينولات) ، والتي شجعت على استخدام هذه المنتجات المرنة للتطبيقات الحيوية وتعمل كعامل اقتران للبوليمرات المحبة للماء والطارئة للماء.

A novel anti-corrosion and antibacterial integrated MAO/PCNZ composite coating on AZ31B Mg alloy

Magnesium and its alloys possess elastic modulus close to natural bone and degradable effects, making them widely applied in bone implantation. However, their rapid corrosion in a simulated body fluid restricts further application. This work firstly employs micro arc oxidation (MAO) technique to in situ grow a corrosion-resistant ceramic layer on the surface of AZ31B Mg alloy. Subsequently, nano ZnO particles are modified using a silane coupling agent and then incorporated into a poly(ε-caprolactone) coating with chitosan through a simple blending and micellar method to obtain the PCNZ composite coating. The chemical composition and micro structure are characterized by FTIR, XRD, SEM and AFM. Electrochemical tests and antibacterial experiments indicate that PCNZ composite coating exhibits excellent long-term corrosion resistance and certain antibacterial ability, demonstrating potential application in the field of bone implantation.

Preparation and characterization analysis of modified bentonite-based powder for improving explosion suppression effects

Properties of explosion suppression material have a significant impact on controlling the explosion propagations. Bentonite, with a large surface area and abundant pore structure, can adsorb free radicals during the explosion reactions. It is a kind of ideal explosion suppression materials. However, bentonite can easily absorb moisture and solidify into cakes in a humid environment, which lacks the possibilities of reactions with radicals in explosions and results in a poor suppression effect. To enhance the space suspension property of bentonite, in this paper, three surface modification methods are proposed to prepare the modified bentonite-based powder by using a silane coupling agent modification, silica encapsulation modification, and quaternary ammonium salt insertion modification. Then, changes in the characteristics of modified bentonite are analyzed and characterized using FTIR, SEM, et al. The results show that the pore structures fundamentally changed and surface is poor combination with water, which greatly solves the “Caking” problem.

Study on bulletproof performance of functionalized fabrics modified by microcapsules

AbstractThe incorporation of microcapsule particles (MPs) into fabrics offers the potential to enhance both the friction between fabric yarns and the bulletproof impact performance. In this study, MPs were prepared using the interfacial polymerization method. Furthermore, an innovative modification of the AF fabric was achieved by introducing a silane coupling agent and MPs. This resulted in the development of a microcapsules‐aramid fibers (MPs‐AF) composite material exhibiting excellent protective performance. The characterization experiment demonstrated the successful adhesion of MPs to the AF fabric, forming a robust bond between the fiber and the particles. Importantly, the modification process did not have any adverse effects on the fiber structure. The study further investigated the ballistic performance and protection mechanism of the modified fabrics through mechanical performance tests and ballistic impact tests. The yarn pull‐out experiment revealed that the MPs‐AF composite material exhibited a significant increase in pull‐out force, with a remarkable improvement of 175.6% compared to AF fabric. In the ballistic impact experiments, the MPs‐AF composite material demonstrated a substantial increase in ballistic limit velocity, rising from 52 to 118 m/s when compared to the AF fabric. These findings highlight the potential application of the MPs‐AF composite material in the field of wearable protection.Highlights Fiber surface modification grafting reaction. A simple and novel solution impregnation method was used to prepare modified AF. Preparation of microcapsule particles by interfacial polymerization. Green new fiber bulletproof material. Chemical grafting produces strong chemical bonds to increase interfacial resistance.

Ag Nanoparticles@Au Nanograting Array as a 3D Flexible and Effective Surface-Enhanced Raman Scattering Substrate.

Surface-enhanced Raman scattering (SERS) is a powerful analytical technique for chemical identification, but it remains a great challenge to realize the large-scale and well-controlled fabrication of sensitive and repeatable SERS substrates. Here, we report a facile strategy to fabricate centimeter-sized periodic Au nanograting (Au-NG) decorated with well-arranged Ag nanoparticles (Ag-NPs) (denoted as Ag-NPs@Au-NG) as a three-dimensional (3D) flexible hybrid SERS substrate with high sensitivity and good reproducibility. The Au-NG patterns with periodic ridges and grooves are fabricated through nanoimprint lithography by employing a low-cost digital versatile disc (DVD) as a master mold, and the Ag-NPs are assembled by a well-controlled interface self-assembly method without any coupling agents. Multiple coupling electromagnetic field effects are created at the nanogaps between the Ag-NPs and Au-NG patterns, leading to high-density and uniform hot spots throughout the substrate. As a result, the Ag-NPs@Au-NG arrays demonstrate an ultrahigh SERS sensitivity as low as 10-13 M for rhodamine 6G with a high average enhancement factor (EF) of 1.85 × 108 and good signal reproducibility. For practical applications, toxic organic pollutants including crystal violet, thiram, and melamine have been successfully detected with high sensitivity at a low detection limit, showing a good perspective in the rapid detection of toxic organic pollutants.