Types Of Silane Coupling Agents Research Articles

Physical properties and morphology of siloxane–polyacrylate dispersion and coating films

The aim of this work was to study the morphology and physical properties of siloxane–polyacrylate (SPA) dispersion and coating films. The SPA dispersion was synthesized by seeded emulsion polymerization using two different types of silane coupling agents, i.e., vinyltriethoxysilane (VTES) and 3-(trimethoxysilyl) propyl methacrylate (MPTMS), at 1–9% by weight. The effect of the type and content of silane coupling agent used in the SPA dispersion synthesis on the resulting morphology and physical properties of the obtained SPA dispersion and coating films were studied. The results revealed that SPA dispersion synthesized using VTES exhibited a smaller particle size and a higher stability than those using MPTMS. Furthermore, the hydrophobic surfaces and water repellence of the coating films using VTES in the emulsion were higher than those using MPTMS, due to the smoother surface morphology.

Synthesis of a polysiloxane coating and investigation of its functional properties with high hardness and flame retardancy

A high hardness and flame retardancy polysiloxane coating was prepared by the sol−gel method and its surface profile, thermal stability and flame retardancy were investigated. The physical properties and surface morphology were significantly effected by the m(R)/m(Si) values and types of silane coupling agents. The hardness of the polysiloxane coating films exhibited an increase as the ratio of m(R)/m(Si) decreases. The addition of KH560 to polysiloxane enabled the formation of hydrophobic property with high hardness and adhesive film on the polyacrylate substrate. The increase in cross-linking degree of the polysiloxane was found to be effective in improving the thermal stability. The microcalorimetry test confirmed that lowest peak heat release rate of polysiloxane was 30.44 W/g and the total heat release was 9.6 kJ/g. This article highlighted the high hardness and flame retardancy properties of the polysiloxane coating that has a potential use in protective films.

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.

The effect of amino-silane coupling agents having different molecular structures on the mechanical properties of basalt fiber-reinforced polyamide 6,6 composites

To improve the interfacial strength between basalt fibers (BFs) and PA6,6, amino-silane coupling agents were applied to BF-reinforced polyamide 6,6 composites. The effects of their molecular structures, especially the number of amino groups and the corresponding chain lengths, on the mechanical properties of basalt fiber-reinforced PA6,6 composites (BFRP) were then investigated. The results showed that even with the same type of silane coupling agent, the distinctive feature in its molecular structure is eventually displayed in the difference in the reinforcing mechanism to strengthen the interphase between BF and PA6,6, and consequently, its impact on the strength of the composites. The adhesive properties of BF to PA6,6 were promoted by the polar amino groups as well as the non-polar long CH2 chains of the silane coupling agents introduced to the BF surface. As the number of polar amino groups increased, the intermolecular hydrogen bonding with the CONH groups in PA6,6 increased, thus leading to enhanced interfacial adhesion between BF and PA6,6. The interfacial adhesion was also improved by the physical cross-linking formed from the chain entanglement between the silane molecules and PA6,6 as the number of non-polar long CH2 chains of the silane coupling agents increased. The tensile strength of their composites showed similar interfacial shear strength tendencies between BF and PA6,6 in the order of long-chain-, tri-, di-, and mono-amino-silane-treated BFRPs. Long-chain amino-silane was shown to be the most effective in strengthening the interphase between BF and PA6,6. This is because long-chain amino-silane induces strong chemical and physical bonding with PA6,6 as it has a large amount of amino groups in the terminate part and long CH2 chains in the spacer part.

An evaluation of modified Kaolinite surface on the crystalline and mechanical behavior of polypropylene

An approach for the surface modification of Kaolinite with two types of silane coupling agents is reported to investigate how structural chemical differences would influence the behavior of crystallization, crystalline structure and mechanical properties of polypropylene. Functionalization of Kaolinite showed that the mass ratio and the chemical structure of the silanes directly affected the mechanical and crystalline behavior of the polymer matrix. Compared to octyltriethoxysilane, functionalization with isobutyltrimethoxysilane led to an increase in the surface energy of kaolinite acting as a nucleating agent. This characteristic induced the formation of structures that gave the composite ductile behavior due to intra-spherulitic deformations under mechanical stress. These results have great potential to stimulate both research and industrial interest in the development of new materials based on a polypropylene matrix.

Improvement of the interface bonding between date palm fibers and polymeric matrices using alkali-silane treatments

In this paper, the effect of chemical treatments on date palm fibers (DPFs) properties was studied; DPFs were first treated with a 5 wt% NaOH aqueous solution for 1 h and then modified using two types of silane coupling agents (3-Mercaptopropyltrimethoxysilane and 3-Aminopropyltrimethoxysilane) with various concentrations (0.1, 0.5, 1 and 2 wt%) to improve the interfacial properties of DPFs with polymeric matrices. SEM observations showed the formation of silane layers on the alkalized surface of DPFs. The Fourier-transform infrared (FTIR) results showed that the salinization was successfully performed by forming covalent Si–O–C bonds between DPF and silane coupling agent. The pull-out behavior of treated fibers was also investigated using two matrices; polyurethane (PU) and epoxy. The obtained results showed that the treatments have successfully improved the interfacial bond characteristics of DPF-PU and DPF-Epoxy systems.

Preparation and characterization of modified SiO2 nanospheres with dichlorodimethylsilane and phenyltrimethoxysilane

In this study we synthesized spherical nanosilica by the Sol-Gel method using tetraethyl orthosilicate (TEOS), and the average particle diameter was measured by scanning electron microscopy (SEM). The surface of silica nanoparticles was modified with two kinds of silane coupling agents: dichlorodimethylsilane (DCDMS) and phenyltrimethoxysilane (PhTMS). We investigated the effect of the type of silane coupling agent with different functional groups (alkoxy or chloro) on the surface properties of modified silica by various analytical methods, i.e., FT-IR spectroscopy, CHN analysis, UV-visible spectra and thermogravimetric analysis (TGA) measurements. The particles modified with DCDMS showed larger grafting density from CHN analysis and higher weight loss from TGA measurement indicating the higher content of silane grafted on the surface of SiO2 nanoparticles. We suggest that the variations in grafting were dependent on the silane condensation which indicating the greater ability of condensation reaction of DCDMS with OH groups of silica rather than PhTMS.

Exploring the comparative effect of silane coupling agents with different functional groups on the cure, mechanical and thermal properties of nano-alumina (Al2O3)-based natural rubber (NR) compounds

The surface of sol–gel-synthesized nano-alumina (Al2O3) was modified by three types of silane coupling agents with different specific functionalities, namely 3-aminopropyltriethoxysilane (APTES), triethoxy(octyl)silane (OCTEOS) and bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT). The aim of the present study was to explore the effect of both unmodified and surface-modified nano-Al2O3 on the cure characteristics, mechanical properties, cross-link density and thermal stability of natural rubber (NR) nanocomposites. Results revealed that silane coupling agents were very effective to enhance maximum rheometric torque (R∞) and mechanical properties like modulus and tensile strength of nano-Al2O3-based NR nanocomposites. APTES offered higher value of cure rate index for NR compounds as compared to two other silane coupling agents. Among three silane coupling agents, TESPT provided highest improvement in the mechanical properties of NR/nano-Al2O3 composites. This might be explained by considering excellent improvement in the cross-link density of NR compounds in the presence of TESPT-treated nano-Al2O3. The incorporation of both TESPT- and OCTEOS-modified nano-Al2O3 into the NR matrix markedly improved the thermal stability of NR composites. Moreover, bi-functional silane TESPT not only increased the hydrophobicity of nano-Al2O3, but also improved the probability of sulfur cross-linking during cure process of NR compounds.

Comparison of aged XLPE power cables restoration by injecting two various anti-failure nanofluids

Abstract This study investigates and compares two different silicone anti-failure rejuvenation fluids based on alumina nanofiller in terms of their capability in rehabilitation and restoration of water tree aged medium voltage cross-linked polyethylene (XLPE) distribution power cable insulations. These two rejuvenation fluids include two types of silane coupling agents used for forming chemical bonds between nanoparticles and cable polymer matrix, filling water tree micro voids and drying the humidity of cable insulation. These two compositions contain γ-alumina nanoparticles which have applications in improving dielectric properties, treating and modifying the surface of the aged insulation and filling water tree micro voids. After injecting the two rejuvenation fluids in two groups of aged cables, dielectric loss factor (tanδ) of the injected samples was measured every week from day 1 to 30 and their results were compared with the new unused and aged samples. Microstructure analysis of the aged and rejuvenated insulations was carried out by scanning electron microscope (SEM) and the chemical bonds of the aged and rejuvenated samples were detected and monitored by Fourier transform infrared (FTIR) spectroscopy. The type of elements and the weight percent of the absorbed elements on the surface of rejuvenated insulations were studied by energy disperse X-ray spectroscopy (EDX). After one month from the injection, it was revealed that tanδ of the injected samples (both rejuvenation fluids) decreased in a way that their tanδ values were even less than the new unused samples. Results of SEM analysis illustrated that rejuvenation fluids filled the water tree micro voids and modified the insulation surfaces. FTIR analysis also indicated that both silicone fluids penetrated in cable insulations and the peaks related to silicone and alumina bonds could be clearly observed. EDX test demonstrated and compared the amount and weight percentage of the rejuvenated elements such as silicone, aluminum and iron. Finally, through the results of these 4 tests, the best rejuvenation composition was selected among these two compositions.

Effect of silane coupling agent on improving the adhesive properties between asphalt binder and aggregates

Moisture damage negatively affects the pavement service life. A typical way to delay the moisture damage is to improve the adhesion between asphalt binder and aggregates. The purpose of this paper is to investigate the effects of silane coupling agent (SCA) on improving the adhesion between asphalt binder and aggregates. In this paper, the contact angles of the aggregates modified by different SCA hydrolysates were measured. The adhesion energy and stripping energy between asphalt binder and aggregates modified by different SCA hydrolysates were calculated. Secondly, the tensile strengths between asphalt binder and aggregates before and after immersion in water were measured. Lastly, the interfacial interactions between SCA and the aggregates were studied by Fourier transform infrared (FTIR) and scanning electronic microscopy (SEM). The surface energy results prove that the SCA can significantly improve the adhesion energy and stripping energy between the aggregates and the asphalt binder. The tensile test results show that the tensile strength of the aggregates modified with a type of SCA (KH550) hydrolysate before immersion in water was increased by 58%, and the tensile strength after the immersion in water was increased by 155%. Based upon these results, it can be concluded that using SCA has a superior effect on improving adhesive properties between asphalt binder and aggregates.

Effect of Silane Coupling Agent on Tribological Properties of Hemp Fiber-Reinforced Plant-Derived Polyamide 1010 Biomass Composites.

We have studied the effects of silane coupling agents used for the surface treatment of fiber on the tribological properties of hemp fiber (HF) reinforced plant-derived polyamide 1010 (PA1010) biomass composites. Hemp fibers were surface-treated by two surface treatment methods: (a) alkali treatment by sodium hydroxide solution and (b) surface treatment by silane coupling agents. Three types of silane coupling agents, namely aminosilane, epoxysilane and ureidosilane were used. These HF/PA1010 biomass composites were extruded using a twin extruder, and injection-molded. The mechanical and tribological properties were evaluated by the ring-on-plate type sliding wear test. It was found that tribological properties of HF/PA1010 biomass composites improved with the surface treatment by the silane coupling agent. This may be attributed to the change in the mode of friction and wear mechanism by the interfacial adhesion between fiber and matrix polymer according to the type of silane coupling agent used. In particular, the ureidosilane coupling agent showed the best improvement effect for the tribological properties of these biomass composites in this study.

Enhanced dielectric constant of acrylonitrile–butadiene rubber/barium titanate composites with mechanical reinforcement by nanosilica

Acrylonitrile–butadiene rubber (NBR), a synthetic rubber having C≡N dipoles, was chosen as a polymer matrix with a higher dielectric constant than other non-polar rubber like silicone rubber or ethylene–propylene–diene monomer. Barium titanate (BaTiO3), as a ferroelectric material, with a high dielectric constant and low dielectric loss was selected as a main filler to further enhance the dielectric constant of NBR. An effective silane coupling agent (KH845-4), selected from five types of silane coupling agents with different characteristic functional groups, was used to modify the surface of BaTiO3 particles to enhance its interfacial adhesion to the matrix. Fourier transform infrared spectroscopy (FTIR) was used to verify the successful modification. The addition of BaTiO3 obviously enhanced the dielectric constants. In particular, an uncommon pattern of dielectric loss has been displayed and analyzed in this paper. Nevertheless, the reinforcing effect of mechanical strength of the NBR/treated BaTiO3 composites is limited. On this basis, the addition of nanosilica (SiO2), replacing part of NBR, improved the mechanical strength. Confirmed by scanning electron microscopy (SEM), the SiO2 and treated BaTiO3 particles were dispersed well in the NBR matrix. The tensile strength was increased from 4.33 to 6.12 MPa when SiO2 accounted for 4%. Moreover, the curing characterizations, crosslinking density, resistivity, and oil resistance were evaluated. This composite material can be used in manufacturing electronic devices, which are subjected to oily environments for a long time.

Functionalized TiO2 nanoparticles by single-step hydrothermal synthesis: the role of the silane coupling agents.

A simple, robust and versatile hydrothermal synthesis route to in situ functionalized TiO2 nanoparticles was developed using titanium(IV) isopropoxide as Ti-precursor and selected silane coupling agents (3-aminopropyltriethoxysilane (APTES), 3-(2-aminoethylamino)propyldimethoxymethylsilane (AEAPS), and n-decyltriethoxysilane (DTES)). Spherical nanoparticles (ca. 9 nm) with narrow size distribution were obtained by using DTES or by synthesis performed without silane coupling agents. Rod-like nanoparticles along with 9 nm spherical nanoparticles were formed using aminosilane coupling agents because of a combination of oriented attachment of nanoparticles and specific adsorption of the aminosilane on crystallographic faces of anatase nanoparticles. The nanoparticles were functionalized in situ and became hydrophobic as silanes reacted to form covalent bonds on the surface of TiO2. The versatility of the aqueous synthesis route was demonstrated, and by selecting the type of silane coupling agent the surface properties of the TiO2 nanoparticles could be tailored. This synthesis route has been further developed into a two-step synthesis to TiO2–SiO2 core–shell nanoparticles. Combustion of the silane coupling agents up to 700 °C leads to the formation of a nanometric amorphous SiO2 layer, preventing growth and phase transition of the in situ functionalized nanoparticles.

Effect of bacterial cellulose on properties of poly(lactic acid)

The aim of this research is to study the mechanical and thermal properties of composites based on poly(lactic acid) (PLA) by using bacterial cellulose (BC) as a reinforcement. BC is produced by Acetobacterxylinum. To improve the interfacial adhesion between the BC and PLA matrix, BC is treated with different types of silane coupling agents (BC: Silane = 1: 0.00943) namely 3-aminopropyltrimethoxysilane (APS), N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (DMS) and N1-(3-trimethoxysilyl propyl) diethylenetriamine (TMS). PLA is also modified with maleic anhydride (MA) in order to improve the electrophilicity property of PLA. In this work, reactive composites of BC reinforced PLA are prepared using a melt compounding process with twin screw extruder and injection molding machine. The effect of various silane coupling agents of 3 types and various contents of BC (1, 3, 5wt%) on mechanical and thermal properties are studied by using universal testing machine, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The DSC analysis is shown that the addition of BC particles significantly affect the crystallization rate of PLA because BC particles can act as a nucleating agent. The addition of 5 wt% BC to PLA provides more crystalline region than BC addition of 3 wt% and 1 wt% to PLA. Moreover, PLA composite with BC modified by TMS has the highest crystalline volume, followed by the DMS and APS, respectively. Young’s modulus of PLA/5 wt% BC-TMS composite has the greatest increase compared with neat PLA. Moreover, PLA composites with BC treated by DMS have higher modulus than the one that is treated with APS.

Preparation of superhydrophobic nanocomposite fiber membranes by electrospinning poly(vinylidene fluoride)/silane coupling agent modified SiO2 nanoparticles

ABSTRACTSuperhydrophobic nanocomposite fiber membranes were prepared by blend electrospinning of poly(vinylidene fluoride) (PVDF) mixed with silane coupling agent modified SiO2 nanoparticles. The nanoparticles were prepared by the sol–gel method, and the average particle diameter was measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The effects of the type of silane coupling agent, such as n‐octyltriethoxysilane, vinyltrimethoxysilane (A‐171), and vinyltriethoxysilane (A‐151), and the mass ratio of the modified silica particles and PVDF on the surface wettability of the composite fiber membrane were investigated. The results indicated that the incorporation of silane coupling agent modified silica particles into the PVDF membrane increased the roughness of the surface and formed micro/nano dual‐scale structure compared to the pristine PVDF membrane, which was responsible for the superhydrophobicity and self‐cleaning property of the nanocomposite fiber membranes. The value of water contact angle (CA) increased with the increase of the content of modified SiO2 nanoparticles in the nanocomposite membrane, ranging from 149.8° to 160.1° as the mass ratio of modified 170 nm SiO2 with PVDF matrix increased from 0.5:1 to 5:1, indicating the membrane possesses a superhydrophobic surface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44501.

Silane-modified halloysite/Fe3O4 nanocomposites: Simultaneous removal of Cr(VI) and Sb(V) and positive effects of Cr(VI) on Sb(V) adsorption

New adsorbents were successfully prepared by in-situ growing Fe3O4 nanoparticles on halloysite nanotubes (HNTs) followed by subsequent modification with silane coupling agents. The as-prepared composites were characterized by TEM, XRD, TGA, ATR-FTIR, BET, and Zeta potential. The results confirm that Fe3O4 nanoparticles were successfully decorated on internal nanotube surfaces and silane coupling agents were grafted onto the external surfaces. Among the four types of silane coupling agents modified HNTs/Fe3O4, anilino-methyl-triethoxysilane (KH-42) modified HNTs/Fe3O4 composite exhibits the highest capacity for single adsorption of Cr(VI) and simultaneously adsorption of Cr(VI) and Sb(V). Moreover, the maximum Sb(V) removal efficiency increases from 67.0% in the single-solute system to 98.9% in the bi-solute system, suggesting that the presence of Cr(VI) enhances the Sb(V) removal by m-HNTs/Fe3O4. ATR-FTIR and XPS results reveal the existence of N–O–Cr bonds on adsorbent surfaces in the corresponding single-solute system, while Cr–O–Sb binding forms in the bi-solute system, which is responsible for the synergistic promoting effect on simultaneous adsorption of Cr(VI) and Sb(V) by m-HNTs/Fe3O4. The present work evinces that m-HNTs/Fe3O4 holds the potential in treating industrial wastewater and natrual surface water with coexisting heavy metals such as Cr(VI) and Sb(V).

Surface modification of mordenite in Nafion composite membrane for direct ethanol fuel cell and its characterizations: Effect of types of silane coupling agent

Mordenite (MOR) has been used to solve the alcohol crossover in direct ethanol fuel cells. However, the lack of compatibility has been a problem. This paper shows the compatibility improvement of MOR in a Nafion composite membrane for use in a fuel cell using four types of silane coupling agents: gamma-glycidoxypropyltrimethoxysilane (GMPTS), (3-mercaptopropyl)trimethoxysilane (MPTS), (3-mercaptopropyl)triethoxysilane (MPTES) and (3-mercaptopropyl)methyl-dimethoxysilane (MPDMS). The coupling agents were used to treat the MOR surface before mixing with Nafion. Each type of silane was treated carefully and differently, depending on its structure. Their characterizations were also described. The results showed that better compatibility and a noticeable reduction in ethanol permeability were achieved when using all silane-treated MOR in the composite. It was found that the Nafion/MOR-MPTES membrane had the highest proton conductivity at all temperature ranges from 30 to 70°C. This was due to the fact that the sulfhydryl (SH) functional group in MPTES provided the sulfonic group in its structure after the oxidation in the surface treatment process. These sulfonic groups at the MOR surface facilitated proton transport and improved the selectivity of the membrane.

실란커플링제 종류가 친수성 코팅 필름의 물성에 미치는 영향

In order to improve the hydrophilic property of polymer films, coating solutions which showed a good hydrophilic property, were prepared by the sol-gel method. The coating solutions were prepared by adding different types of silane coupling agents (aminosilane, epoxysilane and acrylsilane) to a colloidal silica (15 nm diameter). The solutions prepared by adding aminosilane resulted in gels which could not be used as coating solutions. On the other hand, the coating solutions prepared by the addition of epoxysilane showed contact angles of 10~15o and good hydrophilic property at R=0.10~0.15 (R=silane coupling agent/colloidal silica weight ratio). In addition, the coating solutions prepared by the addition of acrylsilane at R=0.03~0.07, exhibited contact angles of 5~10o, which means better hydrophilic property than aminosilane or epoxysilane.

Surface modification of porous alumina filters for CO2 separation using silane coupling agents

Inorganic membranes are becoming increasingly interesting for CO2 gas separation processes considering their potential in CO2 capture and storage for mitigating global warming. Porous alumina filters with the ability of CO2 gas separation were prepared by modifying four types of silane coupling agents: 3-Aminopropyltriethoxysilane (APTES), 3-Ureidopropyltriethoxysilane (Ureido), Octadecyltrimethoxysilane (ODS), and Heptadecafluorodecyltrimethoxysilane (FAS17). CO2/N2 gas selectivity was less than 1.0 for all the filters, meaning that less CO2 gas could permeate the filter, compared with N2 gas. The difference of gas selectivity among the prepared filters was ascribed to two main factors. The first was the relative electric charges of the atoms in both the gas molecules and the functional groups of the silane coupling agents. Oppositely charged atoms result in a physical interaction between CO2 molecule and the silane coupling agent at the surface of porous alumina structure. The second factor was the configuration of the CO2 molecule. It could be considered that the oxygen atoms at the exterior of the CO2 molecule have a stronger physical interaction with other charged species than the carbon atoms located at the center of the molecule.

Facile synthesis of functionalized ionic surfactant templated mesoporous silica for incorporation of poorly water-soluble drug

The present paper reported amino group functionalized anionic surfactant templated mesoporous silica (Amino-AMS) for loading and release of poorly water-soluble drug indomethacin (IMC) and carboxyl group functionalized cationic surfactant templated mesoporous silica (Carboxyl-CMS) for loading and release of poorly water-soluble drug famotidine (FMT). Herein, Amino-AMS and Carboxyl-CMS were facilely synthesized using co-condensation method through two types of silane coupling agent. Amino-AMS was spherical nanoparticles, and Carboxyl-CMS was well-formed spherical nanosphere with a thin layer presented at the edge. Drug loading capacity was obviously enhanced when using Amino-AMS and Carboxyl-CMS as drug carriers due to the stronger hydrogen bonding force formed between surface modified carrier and drug. Amino-AMS and Carboxyl-CMS had the ability to transform crystalline state of loaded drug from crystalline phase to amorphous phase. Therefore, IMC loaded Amino-AMS presented obviously faster release than IMC because amorphous phase of IMC favored its dissolution. The application of asymmetric membrane capsule delayed FMT release significantly, and Carboxyl-CMS favored sustained release of FMT due to its long mesoporous channels and strong interaction formed between its carboxyl group and amino group of FMT.