Showing papers on "Silane published in 2017"

Excellent corrosion protection performance of epoxy composite coatings filled with amino-silane functionalized graphene oxide

Abstract: Epoxy coatings containing graphene oxide (GO) and amino-silane modified GO (A-GO) with various weight fractions (0.05, 0.1, 0.3, and 0.5 wt%) are prepared to investigate the effect of silane modified GO on performance of nanocomposite coatings. (3-Aminopropyl) triethoxysilane (APTES) is used as organosilane for A-GO synthesis. A-GO is characterized by FTIR, XRD, FE-SEM, and EDS. The dispersion quality of nanosheets in epoxy coating is examined by FE-SEM, revealing the interfacial interaction of GO in coating has improved via silane modification. Besides, the pull-off adhesion strength of epoxy coating to substrate increases by about two times via adding A-GO. The results of electrochemical impedance spectroscopy show that epoxy/A-GO coatings can provide superior corrosion protection performance and maximum corrosion resistance is achieved via adding 0.1 wt% A-GO. By increasing the loading of A-GO, the barrier properties decrease due to agglomeration of nanosheets in polymer matrix.

Functionalization of halloysite nanotubes (HNTs) via mussel-inspired surface modification and silane grafting for HNTs/soy protein isolate nanocomposite film preparation

Abstract: The use of a catechol derivative (dopamine) for surface modification of the internal/external halloysite nanotubes (HNTs) and facilitating epoxy-functionalized silane grafting on the HNTs surfaces via a poly(dopamine) (PDA) ad-layer were demonstrated in this study. Aqueous dopamine was bound to alumina/silica at the tube and self-polymerized to form a thin, surface-adherent PDA ad-layer in an alkaline environment. The silane agent (KH560) was then supplied to the PDA-coated HNTs (PDHNTs) surface to introduce epoxy groups. The versatile promotion of the PDA layer in the PDHNTs was confirmed by the X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The surface modification of the PDA coating and silane grafting was successfully carried out. The natural components-based PDHNTs-O/soy protein isolate (SPI) nanocomposite film was obtained due to the penetration and entanglement of the SPI chains to the PDHNTs-O nanotubes and their lifting luminal and interfacial adhesions via covalent/physicochemical bonding. Compared to the unmodified SPI film, the tensile strength of the PDHNTs-O/SPI nanocomposite films increased from 5.90 MPa to 8.73 MPa, the Young's modulus improved by 54.5% and moisture absorption decreased by 47.1%. The functionalized surfaces also improved the dispersion and compatibility of the PDHNTs-O to the SPI matrix.

Fabrication and characterization of layered double hydroxide/silane nanocomposite coatings for protection of mild steel

Abstract: In this paper, environmentally friendly layered double hydroxide nanoparticles/silane hybrid nanocomposite coatings were fabricated on mild steel substrate. Zinc–aluminum layered double hydroxides (Zn–Al LDHs) pillared with different anions (nitrate, molybedate and phosphate) were synthesized and characterized by X-ray diffraction (XRD). Various LDHs was employed in a hybrid silane coating based on mixture of tetraethyl ortosilicate (TEOS) and aminopropyl triethoxy silane (APTES). The silane coatings including LDHs were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and contact angle measurement. Then, the corrosion characterization of the coatings was investigated by electrochemical impedance spectroscopy (EIS), polarization and electrochemical noise (EN) techniques. Addition of LDHs to the sol–gel film increased its barrier properties due to their planar structure. The results revealed that the silane coating in the presence of phosphate could provide superior electrochemical corrosion protection compared to the sol–gel film which is solely incorporated with molybedate and nitrate.

Electrochemical investigations of the corrosion resistance of a hybrid sol–gel film containing green corrosion inhibitor-encapsulated nanocontainers

Abstract: In the present study, the effect of Nettle loaded nanocontainers (Nettle-NCs) on the active corrosion inhibition properties of a silane bi-layer coating was studied. In addition, the synergistic inhibition between the Nettle-NCs and zinc acetate (ZA) was studied. Results obtained from electrochemical impedance spectroscopy (EIS) test demonstrated the effective synergistic corrosion inhibition of mild steel by silane coating containing Nettle-NCs and ZA. The active performance of Nettle-NCs/Silane bi-layer coatings on the MS panels was studied by electrochemical impedance spectroscopy (EIS) and salt spray tests.

Argon plasma treatment of fluorine-free silane coatings: a facile, environment-friendly method to prepare durable, superhydrophobic fabrics

Abstract: A novel method to prepare durable superhydrophobic fabrics through pre-applying an alkyl silane (alkyl chain longer than C15) onto fabric substrate and by subsequent vacuum plasma treatment in argon is reported. The treated fabrics show a contact angle of 154.2° with low contact angle hysteresis (sliding angle 4.5°). The coatings are durable and can withstand 150 cycles of standard laundries. The argon plasma treatment is found to significantly enhance SiOSi bonding among the silane molecules, leading to a highly crosslinked silica network. The silane coating also shows high optical transparency. Apart from fabrics, other substrates such as filter paper, plastic film, glass slide, silicon wafer, and metal are treated in a similar way, and all the treated surface show durable hydrophobicity, though the contact angle is lower than that of the coated fabrics. Post-crosslinking of silane through argon plasma treatment may offer a facile but environment-friendly way to prepare durable superhydrophobic fabrics.

Effect of silane/nano-silica on the mechanical properties of basalt fiber reinforced epoxy composites

Abstract: The present study explains the role of surface modification of constituent materials on composite material performance. The influence of silane and nano-hybrid coatings on mechanical properties of basalt fibers and composite materials on their base was investigated. Infrared spectroscopy indicated that modification of basalt fiber surface and nano-SiO2 was successfully applied. The surface modification leads to the significant increase in the tensile strength of basalt fibers compared to the non-coated fibers. The tensile strength of silane-treated fibers was established 23% higher than the non-coated fibers, indicating that silane plays a critical role in the strength retention of basalt fibers. Also it was pointed out that silane coupling agents can be used for the preparation of the nano-hybrid coating. Addition of SiO2 nanoparticles into the fiber surface was incorporated to enhance the interfacial bonding of basalt fiber reinforced epoxy composite.

The influences of silanes on interfacial adhesion and surface properties of nanocellulose film coating on glass and aluminum substrates

Abstract: Nanocellulose is a natural polymer containing abundant hydroxyl groups which can create the network of hydrogen bonds between intra- and inter-molecular cellulose chains and also react with many other functional molecules. These interactions are helpful to film formation and surface modification. Silylation is a well-known modification, in which silane is substituted into a molecule for the improvement of desired properties such as hydrophobization, antimicrobial activity, and compatibilization with plastics for composites. However, to our knowledge, there is no study regarding the silane-modified nanocellulose for adhesion improvement even though nanocellulose film has potential for applications as a protective coating, insulation coating, biomedical coating, etc. Therefore, in this work nanofibrillated cellulose in aqueous suspension - obtained from hemp stubs - was used as a coating material. Various silanes containing dissimilar functional groups were employed in order to improve poor adhesion of nanocellulose films on glass and aluminum substrates and also enhance their physical and mechanical properties. It was found that silane containing an amino group provided the optimum increase of adhesion performance when compared with epoxy and methacryloxy groups, in which higher ratio of amino silane tended to give better adhesion on glass and aluminum substrates. Moreover, amino silane was capable of improving surface hardness, elastic modulus, and scratch resistance of coating film and also providing the satisfied results of optical properties and hydrophobic characteristic to nanocellulose film.

The Effect of Different Coupling Agents on Nano-ZnO Materials Obtained via the Sol-Gel Process.

Abstract: Hybrid nanomaterials based on zinc oxide were synthesized via the sol-gel method, using different silane coupling agents: (3-glycidyloxypropyl)trimethoxysilane (GPTMS), phenyltriethoxysilane (PhTES), octyltriethoxysilane (OTES), and octadecyltriethoxysilane (ODTES). Morphological properties and the silane precursor type effect on the particle size were investigated using dynamic light scattering (DLS), environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The bonding characteristics of modified ZnO materials were investigated using Fourier transform infrared spectroscopy (FTIR). The final solutions were deposited on metallic substrate (aluminum) in order to realize coatings with various wettability and roughness. The morphological studies, obtained by ESEM and TEM analysis, showed that the sizes of the ZnO nanoparticles are changed as function of silane precursor used in synthesis. The thermal stability of modified ZnO materials showed that the degradation of the alkyl groups takes place in the 300-500 °C range. Water wettability study revealed a contact angle of 142 ± 5° for the surface covered with ZnO material modified with ODTES and showed that the water contact angle increases as the alkyl chain from the silica precursor increases. These modified ZnO materials, therefore, can be easily incorporated in coatings for various applications such as anti-corrosion and anti-icing.

Influence of the silanes on the crosslink density and crosslink structure of silica-filled solution styrene butadiene rubber compounds

Abstract: The effects of three silane coupling agents, triethoxy(octyl)silane (TEOS), bis[3-(triethoxysilyl)propyl]disulfide (TESPD), and bis[3-(triethoxysilyl)propyl]tetrasulfide (TESPT) on the filler-rubber interaction, crosslink density and crosslink structure of the silica-filled solution styrene butadiene rubber (SSBR) vulcanizates were studied. High dispersion silica, 7000GR, was used as the filler, and the loading range was varied from 0 to 60 phr. Crosslink density was measured by the swelling method. Experimental results showed that Kraus plot can be applicable to the silica-filled SSBR vulcanizates to separate filler-rubber interaction from the measured swelling data. Filler-rubber interaction increased by increasing sulfur rank in the silane as TEOS < Silica without silanes < TESPD < TESPT. Sulfurless silane, i.e. TEOS, only worked as a covering agent for hydrophobating silica surface. Silica without silane show high filler-rubber interaction than TEOS system because chain-end functionalized SSBR w...

Catalytic Dehydrogenative Coupling of Hydrosilanes with Alcohols for the Production of Hydrogen On-demand: Application of a Silane/Alcohol Pair as a Liquid Organic Hydrogen Carrier

Abstract: The compound [Ru(p-cym)(Cl)2 (NHC)] is an effective catalyst for the room-temperature coupling of silanes and alcohols with the concomitant formation of molecular hydrogen. High catalyst activity is observed for a variety of substrates affording quantitative yields in minutes at room temperature and with a catalyst loading as low as 0.1 mol %. The coupling reaction is thermodynamically and, in the presence of a Ru complex, kinetically favourable and allows rapid molecular hydrogen generation on-demand at room temperature, under air, and without any additive. The pair silane/alcohol is a potential liquid organic hydrogen carrier (LOHC) for energy storage over long periods in a safe and secure way. Silanes and alcohols are non-toxic compounds and do not require special handling precautions such as high pressure or an inert atmosphere. These properties enhance the practical applications of the pair silane/alcohol as a good LOHC in the automotive industry. The variety and availability of silanes and alcohols permits a pair combination that fulfils the requirements for developing an efficient LOHC.

Coconut shell powder reinforced thermoplastic polyurethane/natural rubber blend-composites: effect of silane coupling agents on the mechanical and thermal properties of the composites

Abstract: The objective of this work is to modify coconut shell powder (CSP) using various silane coupling agents and to study the effect of modification on the interfacial adhesion and mechanical properties of the fillers in the binary blend of thermoplastic polyurethane and natural rubber. Mechanical properties such as tensile strength, tear strength, hardness and abrasion resistance were evaluated. Results revealed that, compared to triethoxyvinylsilane modified CSP composites, glycidyloxypropyltrimethoxysilane treated CSP showed higher tensile strength and better interfacial adhesion with the matrix. The efficiency of the silane treatment is further characterized by the FT-IR analysis of fillers and the morphological study of both the CSP and the composites. FT-IR studies demonstrated that the silyl parts of both silane coupling agents efficiently grafted to the CSP. SEM images of treated CSPs provide ample evidence for the increased mechanical properties of the composites. The increased thermal stability of is evident from the thermo gravimetric analysis.

Novel dental composite material reinforced with silane functionalized microsized gypsum filler particles

Abstract: Gypsum has been recognized as acceptable for human consumption as a dietary source of calcium. During contact with teeth, it releases Ca2+ ions needed for remineralization of tooth tissue, and therefore based on the concept of remineralization, gypsum may be a strategic additive for dental restorative materials. Hence, the objective of this study was to develop and characterize a novel dental material reinforced with different weight fraction of micro sized gypsum filler particle. A novel composite material was fabricated using conventional resin matrix consisting of Bisphenol-A glycidyl methacrylate (Bis-GMA), tri-ethylene glycol dimethacrylate (TEGDMA), camphorquinone (CQ) and ethyl 4 dimethyl amino benzoate (EDMAB). Four different compositions were prepared by reinforcing different weight percentage (0–3 wt%) of silane functionalized micro sized gypsum particle. Fourier Transformed Infrared spectroscopy (FT-IR), Transmission Electron Microscope (TEM) and Thermogravimetric Analysis (TGA) of silane treated filler were used to study the coupling phenomena between filler and resin. Polymerization shrinkage of composites was evaluated using specific gravity method. The Dynamic Mechanical Analysis (DMA) result revealed that the Glass transition temperature was found to be decreased by 15°C compared to unfilled composite. It was also found that the 2 wt% gypsum content recorded the highest value of storage modulus. Simultaneous Thermal Analysis (STA) result revealed that 2 wt% gypsum filled dental composite exhibited maximum thermal stability. The novel dental material exhibited better physical, optical, mechanical, thermal properties and lowest polymerization shrinkage with maximum conversion. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Effect of MDP-containing Silane and Adhesive Used Alone or in Combination on the Long-term Bond Strength and Chemical Interaction with Lithium Disilicate Ceramics.

Abstract: PURPOSE To evaluate the effect of a silane and an adhesive containing MDP, used alone or combined in the same solution, on the microshear bond strength (μSBS) to lithium disilicate ceramics immediately and after 1-year water storage, and compare the bond strength results with the Raman spectra of the treated lithium disilicate surfaces. MATERIALS AND METHODS A total of 30 CAD/CAM blocks of lithium disilicate (LD; IPS e.max CAD) were cut into four square sections (6 x 6 x 6 mm; n = 60 per group) and processed as recommended by the manufacturer. The LD specimens were divided into 12 groups according to the following independent variables: silane coupling agent (no silane; silane without 10-MDP [MBS, Monobond S]; silane with 10-MDP [MB+, Monobond Plus]) and adhesive + luting composite (no adhesive + Enforce; no adhesive + RelyX Ultimate; Prime & Bond Elect [PBE], a silane- and MDP-free universal adhesive + Enforce; Scotchbond Universal Adhesive [SBU], a silane- and MDP-containing universal adhesive + RelyX Ultimate). After each treatment, cylindrical, transparent matrices were filled with a luting composite and light cured. Specimens were stored in water (37°C for 24 h or 1 year) and submitted to the microshear bond strength (μSBS) test. The failure pattern and μSBS were statistically evaluated (α = 0.05). In addition, specimens were examined for chemical interaction using Raman spectroscopy. RESULTS The use of the adhesive PBE alone showed higher mean μSBS compared with both groups with silane (MSB or MB+) without PBE (p < 0.001) at 24 h. The use of the SBU adhesive or MBS silane alone, as well as MB+ associated with SBU, showed higher mean μSBS (p < 0.001) at 24 h. After 1-year water storage, all groups showed a significant decrease in mean μSBS. However, the application of PBE or SBU associated with MB+ silane showed higher 1-year mean μSBS (p < 0.001). In terms of chemical interaction, when silane (MSB or MB+) was applied, only a slight decrease of Si-O peaks occurred. Otherwise, when PBE or SBU adhesives were applied, methacrylate peaks were only observed in the SBU groups. CONCLUSION The best results in terms of bond strength after water storage were obtained when an MDP-containing silane was associated with a universal adhesive. The use of a simplified bonding protocol that includes either a silane or a universal adhesive is not recommended.