Papers by Keyword: Silanization

Abstract: Hybrid adhesives epoxy-silica-zirconia were prepared and applied to bond aluminum sheet specimens. Silica nanoparticles were synthesized with the sol-gel “in situ” technique utilizing two different precursors, namely tetraethyl orthosilicate (TEOS) and 3 glycidyloxypropyltrimethoxysilane (GPTMS). Zirconia nanoparticles were prepared also with sol-gel technique and added to the hybrid adhesives before curing. The adhesive properties of the prepared materials were improved after performing several physical and chemical treatments to the aluminium specimens. The best apparent shear strength tests were for the adhesive hybrid materials prepared at 100°C with TEOS.

Abstract: This research aims to study the effect of the functionalization of the multiwall carbon nanotubes (MWCNTs) on the mechanical property improvement of phenolic composites for bipolar plate applications in proton exchange membrane fuel cells (PEMFC). The MWCNTs were oxidized by strong acid and silanized by silane coupling agent in order to enhance the interfacial adhesion between the MWCNTs and matrix and were used as reinforcement in the phenolic composites. The silanized MWCNTs was found to improve the mechanical properties of the composites; however, they caused the decrease of electrical conductivity due to the wrapping of the MWCNTs with non-conductive silane molecules. Nevertheless, the conductivity of more than 100 S/cm is maintained to meet the DOE requirement of materials for use as bipolar plates.

Abstract: The science of core-shell nanoparticles requires investigation into several physical and chemical properties of the composite nanoparticles. Unlike the conventional sol-gel or the reverse microemulsion micelle method, we presented here a non-seeded process of encapsulating superparamagnetic magnetite nanoparticles (SPMN) with silica. Physico-chemical analysis of the product was used to confirm the result of the coating procedure. Colloidal suspension of SPMN and silica nanoparticles were synthesised through coprecipitation method and modified Stöber method respectively. Afterwards, both colloidal suspensions of SPMN and silica nanoparticles were sonicated to encapsulate the SPMN with silica. Elemental mapping of the composite particles with electron spectroscopy imaging (ESI) confirmed the core-shell micrograph of the SPMN and silica. The X-ray diffraction pattern (XRD) showed the silica shell to be in amorphous form. FTIR analysis further confirmed the chemical properties of the product to be silica coated SPMN.

Abstract: This paper aims to synthesize by combustion reaction and silanilized of the ZnAl_1.9Eu_0.1O₄, with silane agent 3-aminopropyltrimethoxysilane. The characterization of materials before and after silanization was investigated. Nanoparticles ZnAl_1.9Eu_0.1O₄ was obtained according to the theory of propellants and explosives using the synthesis combustion reaction. The samples were deagglomerated and passed through a sieve of 325 mesh and added to 3-aminopropyltrimethoxysilane, followed by heat shock treatment by ultrasonic and microwave. Subsequently centrifuged and dried at 150 ° C for 24 hours. The samples before and after the silane were characterized by X-ray diffraction, infrared spectroscopy and thermogravimetric analysis. The results indicate the formation of a major phase spinel normal ZnAl₂O₄, and the EuAlO₃ peaks as secondary phase. The FTIR spectra for ZnAl_1.9Eu_0.1O₄ have absorption bands below 1000 cm^-1, and after silanization showed bands of C = O, axial strain - CN and Si-O bands, which proves the silanization. The thermogravimetric curves showed good thermal stability, with mass loss around 30%.

Abstract: In this paper we propose nanoferrites Ni-Zn silanization with 3-aminopropyltrimethoxysilane using the method of reflux and evaluate the effect of silanization on the structure, morphology and magnetism of the magnetic nanoparticles aimed at biological applications. The samples as synthesized and after silanization were characterized by XRD, FTIR, SEM and testing magnetic attraction. The results indicated a single phase inverse spinel Ni-Zn ferrite, high intensity of diffraction peaks and a high basal width of all reflections observed, indicating that the samples are crystalline, and formation of nanoparticles. Morphologically, for nanoferrites Ni-Zn synthesized observed formation of large agglomerates in the form of spongy blocks of frail and after silanization was observed with respect dense pellets, indicating that most particles were rigidly connected by the presence of the agent silane. The characteristic bands of the spinel were observed for the Ni-Zn nanoferrites before and after silanization, and also observed the characteristic bands of silane in confirming the ferrites silanized functionalization of ferrites with the silane agent. Nanoparticles ferrite as synthesized and after silanized were strongly attracted by the presence of a magnet, immediately after the presence thereof indicating that the silane is effective is not interfere with the magnetic particles, maintaining the same magnetic behavior.

Abstract: The aim of the method development in this paper was to tackle the problems with the erythro-2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) methodology: the rather laborious workflow and the loss of material during different steps of the method. In the optimised workflow, The detection limit of MMPB was 0.01 μg/L. Supposing the average of molecular weights of microcystins variants are 1000, the value of the detection limit is equivalent to 0.05 μg/L of microcystins. These results indicated that this method is the most sensitive method for determination of total microcystins, and it could be applied to the monitoring of microcystins in drinking water, reservoirs and freshwater lakes.

Abstract: A series of hierarchical ZSM-48 zeolites was prepared by seed silanization. The structural and textural properties of the hierarchical ZSM-48 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), N2 adsorption-desorption, 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS NMR), and Fourier transform infrared spectroscopy adsorbed by pyridine (Py-IR). It was found that the crystal size of ZSM-48 was significantly reduced by seed silanization. Due to the secondary porosity in the mesopore region generated in hierarchical ZSM-48, both the total surface area and the pore volume of the material have a considerable increase. The enhancement of the textural properties could be controlled by changing the amount of silanizaiton agent.

Abstract: For gelating agent in hydraulic fracturing fluid, the temperature resistance is required. To improve the temperature resistance of Guar gum (GG), it was modified by silanization. The reaction conditions were investigated, and the optimized conditions were as following: the reaction temperature of 85°C, 5: 1 molar ratio of guar gum to TMS-Cl and 4-6 h of reaction time. The viscosity of silanized guar gum (SGG) aqueous gel was greatly improved even high temperature at 80°C.

Abstract: The purpose of this study was to evaluate the effects of silanization of the glass on denture base materials and to evaluate different types of glasses. A total of 136 Poly(methyl methacrylate) (PMMA) (Palapress – Heraeus Kulzer) blocks were prepared in dimensions of 65mm x 10mm x 3mm. PMMA blocks were modified by different ratios of non-silanized and silanized Bioactive Glass Granules (BAG) (Vivoxid) and Inert Glass Granules (IG) (Vivoxid). The blocks were polished under water cooling and divided into 17 groups. (Group 1) No glass (control), (Group 2-5) 3-6-9-12% non-silanized BAG, (Group 6-9) 3-6-9-12% silanized BAG, (Group 10-13) 3-6-9-12% non-silanized IG, (Group 14-17) 3-6-9-12% silanized IG. The specimens were stored in distilled water and weighed (Mettler, Toledo) in days of 1, 2, 3, 7, 14, 21, 30, 45, 60. After water sorption test, the specimens were dried under 80°C and weighed in days of 0, 1, 2, 3, 5, 7, 9 for calculating the solubility values. Statistical analysis was performed using analysis of variance (ANOVA) followed by post-hoc comparisons (Dunnett T3, p<0.05). Water sorption and solubility values were significantly affected by the type and silanizaion of the glass (p<0.05). The highest water sorption value was observed in 12% silanized IG group (1,83±0,04%), whereas the lowest sorption values were recorded with 12% non-silanized BAG group (1,21±0,07%). Contrarily, The highest solubility value was observed in 12% non-silanized BAG group (0,98±0,03%), whereas the lowest solubility values were recorded with 12% non-silanized BAG group (0,34±0,03%). Water sorption and solubility values were affected by the type and silanization of the glass. Silanization improved the physical properties of the glass as well as the properties of the denture base material.

Abstract: In this paper, we present the fabrication and characterization of semiconducting carbon nanotube thin-film field-effect transistors (SN-TFTs). High-k dielectric material, hafnium-oxide (HfOX) is used as the gate-oxide of the device. A Thin-film of semi-conducting single walled carbon nanotube (SWCNT) is deposited on the amino-silane modified HfOX surface. Two types of SN-TFTs with interdigitated source and drain contacts are fabricated using 90% and 95% purity of semiconducting SWCNTs (s-SWCNT), have exhibited a p-type behavior with a distinct linear and saturation region of operation. For 20 µm channel length SN-TFT with 95% pure s-SWCNTs has a peak on-off current ratio of 3.5×104 and exhibited a transconductance of 950 µS. The SN-TFT fabricated with HfOX gate oxide has shown a steep sub-threshold slope of 750 mV/decade and threshold voltage of -0.7 V. The SN-TFT of channel length 50 µm has exhibited a maximum mobility of 26.9 cm2/V•s.