Propyl Trimethoxy Silane Research Articles

A study on the corrosion inhibition properties of silane-modified Fe2O3 nanoparticle on mild steel and its effect on the anticorrosion properties of the polyurethane coating

Fe2O3 nanoparticle was modified with 3-amino propyl trimethoxy silane (APTMS) to enhance its compatibility with the polyurethane coating matrix. The surface chemistry of the Fe2O3 nanoparticles was evaluated by thermal gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. Electrochemical impedance spectroscopy (EIS) was utilized to investigate the electrochemical behavior of the steel specimens dipped in the 3.5% NaCl solutions without and with modified and unmodified Fe2O3 nanoparticles extracts. The morphology of the surface of steel samples was investigated by scanning electron microscope (SEM). Also, the polyurethane nanocomposites were prepared by addition of 2 wt% unmodified and modified nanoparticles. The effects of nanoparticles on the anticorrosion properties of the polyurethane coating were investigated with salt spray and pull-off adhesion tests. Results obtained from FTIR and TGA analyses revealed that about 5% APTMS grafted on the surface of Fe2O3 nanoparticles through physical/chemical bondings. Results obtained from EIS and SEM analyses depicted that the unmodified Fe2O3 nanoparticles showed better corrosion inhibitive performance in the extract form than other samples. However, the surface-modified Fe2O3 nanoparticles enhanced the corrosion protection properties of the polyurethane coating much greater than the unmodified Fe2O3 nanoparticles by enhancing the coating barrier performance.

Synthesis and characterization of novel bifunctional mesoporous silica catalyst and its scope for one-pot deacetalization–knoevenagel reaction

Bifunctional (both sulfonic and amine functionalized) mesoporous silica catalysts were prepared by hydrothermal method. (3-[2-(2-amino ethyl amino) ethyl amino] propyl trimethoxysilane) and (3-mercaptopropyl) trimethoxysilane respectively were used as amine and sulfonic sources. The synthesised bifunctional materials were fully characterized by BET, P-XRD, 29Si CPMAS-NMR, FTIR, XPS and SEM spectral analysis. FTIR and NMR results endorse the successful grafting of organic amines and sulfonic group by surface silanol of silica. The presence of of N and S groups in the catalyst material was confirmed by the XPS spectra. Catalytic activity of the bifunctional material was tested for one-pot deacetalization–knoevenagel reaction, which gave excellent yield (95 %). Catalyst is reusable with little loss of activity up to 4 runs (<6 %).

Separation of Arsenic from Aqueous Solutions by Amino-Functionalized γ-Fe2O3-β-Zeolite

In this research, γ-Fe2O3-β-zeolite nanocomposite was synthesized and functionalized by 3-amino propyl trimethoxysilane. The magnetic functionalized adsorbent was characterized by FTIR, X-ray diffraction, thermal analysis, vibrating sample magnetometry, scattering electron microscopy, and N2 adsorption-desorption techniques. The adsorbent was then used for adsorption of arsenic from aqueous solutions. At optimized conditions the adsorption capacity of 30 mg.g−1 was obtained, which was higher than the previously reported values. The loaded adsorbent was easily separated from the solution by applying an external magnetic field. Regeneration of the adsorbent by NaOH solution indicated that 97% of the initial capacity was remained after four adsorption-regeneration cycles.

Effects of framework structure and coupling modification on the properties of mesoporous silica/poly(methyl methacrylate) composites

Mesoporous silicas (MPSs) with two-dimensional (2D) hexagonal framework (SBA-15) and worm-hole framework (MSU-J) were synthesized with poly(ethylene oxide- b-propylene oxide- b-ethylene oxide) (P123) and α,ω-polyoxypropylene diamine (D2000) as templates, respectively. Both SBA-15 and MSU-J were further modified with γ-(methacryloyloxy) propyl trimethoxy silane (MAPTS) via post-grafting to prepare organic mesoporous silicas (denoted SBA-15-G and MSU-J-G, respectively) with –C = C groups on the surface of mesopores. All mesoporous silicas were employed as filler to prepare improved poly(methyl methacrylate) (PMMA) composites with lower dielectric constant, higher thermal, and mechanical properties. It was found that all mesoporous silicas retained their mesostructure in MPS/PMMA composites to introduce a lot of voids into the composites. So, the dielectric constant of composites decreased with the loading of mesoporous silica and their organic derivatives increased. Also, all composites exhibited stabilized dielectric constant with lower value in comparison to pure PMMA over the whole frequency from 1 to 160 MHz. Specifically, with the addition of MPS to PMMA, the dielectric constants of the composite can be reduced from 2.91 of the pure PMMA to 2.73 and 2.64 by incorporating 4 wt% SBA-15 and 7 wt% MSU-J, respectively. All the composites exhibited improved mechanical properties, glass transmission temperature ( Tg), and thermal stability in comparison to PMMA. All these differences in macro-properties are attributed to the different structure between MPS/PMMA composites and PMMA. MSU-J silica with the larger framework pore size provides the composite with the best improvement in dielectric, thermal, and mechanical properties.

Synthesization, Characterization, and in Vitro Evaluation of Cytotoxicity of Biomaterials Based on Halloysite Nanotubes.

Halloysite is an aluminosilicate clay that has been widely used for controlled drug delivery, immobilization of enzymes, and for the capture of circulating tumor cells (CTCs). Surface modification of halloysite by organosilanes has been explored to improve their properties. In this study halloysite clay nanotubes (HNTs) were functionalized by two different organosilanes: Trimethoxy(propyl)silane (TMPS), and Triethoxy(octyl)silane (EOS). Untreated and modified samples were characterized by scanning electron microscopy (SEM), X-ray diffractometry (XRD), thermogravimetrical analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). Results showed a strong interaction of organosilanes with the chemical groups present in HNTs. Biocompatibility and cytotoxicity of these nanomaterials were determined using C6 rat glioblastoma cells. Our results indicate that prior to functionalization, HNTs show a high biocompatibility and low cytotoxicity. However, HNTs functionalized with EOS and TMPS showed high cytotoxicity by inducing apoptosis. These results allow the identification of potential applications in biomedical areas for HNTs.

Effect of Ammonium Polyphosphate Modified with 3-(Methylacryloxyl) Propyltrimethoxy Silane on the Flammability and Thermal Degradation of Pine-Needles

This paper investigated the influence of ammonium polyphosphate (APP) and ammonium polyphosphate modified with 3-(methylacryloxyl) propyltrimethoxy silane (M-APP) on flame retardancy and thermal degradation of pine needles. The presence of M-APP increased the char residue and decreased the pyrolysis temperature of pine needles observed by TGA. The addition of M-APP shifted the degradation peaks of pine needles to lower temperatures observed by DTG. The cone calorimetry test results showed that the situation of HRR, THR, SPR, TSP and the mass loss (%) on pine needles treated with M-APP was sharply less than the other samples. On the other hand, M-APP prolonged the ignition time (TTI) compared with the other samples. Therefore, M-APP has an overall better performance than APP on pine needles.

Constructing covalent interface in rubber/clay nanocomposite by combining structural modification and interlamellar silylation of montmorillonite.

Strong interfacial interaction and nanodispersion are necessary for polymer nanocomposites with expectations on mechanical performance. In this work, montmorillonite (MMT) was first structurally modified by acid treatment to produce more silanol groups on the layer surface. This was followed by chemical modification of γ-methacryloxy propyl trimethoxysilane molecule (KH570) through covalent grafting with the silanol groups. (29)Si and (27)Al magic angle spinning (MAS) NMR results revealed the microstructural changes of MMT after acid treatment and confirmed the increase of silanol groups on acid-treated MMT surfaces. Thermogravimetric analysis indicated an increase in the grafted amount of organosilane on the MMT surface. X-ray diffraction (XRD) showed that the functionalization process changed the highly ordered stacking structure of the MMT mineral into a highly disordered structure, indicating successful grafting of organosilane to the interlayer surface of the crystalline sheets. The styrene-butadiene rubber (SBR)/MMT nanocomposites were further prepared by co-coagulating with SBR latex and grafted-MMT aqueous suspension. During vulcanization, a covalent interface between modified MMT and rubber was established through peroxide-radical-initiated reactions, and layer aggregation was effectively prevented. The SBR/MMT nanocomposites had highly and uniformly dispersed MMT layers, and the covalent interfacial interaction was finally achieved and exhibited high performance.

In situ emulsion copolymerization of methyl methacrylate and butyl acrylate in the presence of SiO2 with various surface coupling densities

Poly(methyl methacrylate-co-butyl acrylate) (poly(MMA-co-BA))/SiO2 nanocomposite particles with various morphologies were prepared through in situ emulsion copolymerization of methyl methacrylate and butyl acrylate using surface 3-(methacryloyloxy) propyl trimethoxysilane (MPS)-modified SiO2 nanoparticles as nanofillers. The surface MPS-coupling density of SiO2 nanoparticles could influence the hydrophilic–lipophilic properties of SiO2 nanoparticles and subsequently influence the particle morphology of poly(MMA-co-BA)/SiO2 nanocomposite particles. With the increase of the surface MPS-coupling density of SiO2 nanoparticles, the morphology of nanocomposite particles changed from a raspberry-like one to a guava-like one. A formation mechanism of nanocomposite particles with various morphologies was proposed on the basis of the results of polymerization kinetics, particle size evolution in the process of polymerization, and particle size and morphology of the final nanocomposite particles.

Development of slate fiber reinforced high density polyethylene composites for injection molding

During the last decade the use of fiber reinforced composite materials has consolidated as an attracting alternative to traditional materials due to an excellent balance between mechanical properties and lightweight. One drawback related to the use of inorganic fibers such as those derived from siliceous materials is the relative low compatibility with conventional organic polymer matrices. Surface treatments with coupling agents and the use of copolymers allow increasing fiber–matrix interactions which has a positive effect on overall properties of composites. In this research work we report the use of slate fiber treated with different coupling agents as reinforcement for high density polyethylene from sugarcane. A silane (propyltrimethoxy silane; PTMS) and a graft copolymer (polyethylene-graft-maleic anhydride; PE-g-MA) were used to improve fiber–matrix interactions on HDPE-slate fiber. The effect of the different compatibilizing systems and slate fiber content were evaluated by scanning electron microscopy (SEM), dynamic thermomechanical analysis (DTMA) as well as mechanical properties (tensile, flexural and impact). The results show that the use of silane coupling agents leads to higher fiber–matrix interactions which has a positive effect on overall mechanical properties. Interesting results are obtained for composites containing 30wt.% slate fiber previously treated with propyltrimethoxy silane (PTMS) with an increase in tensile and flexural strength of about 16% and 18% respectively.

실란처리 되어진 실리카가 첨가된 에폭시 접착제의 접착박리강도에 관한 연구

본 연구에서는 기존 에폭시수지에 에폭시 콩기름(Epoxidized soybean oil : ESBO)과 실란처리 되어진 실리카가 첨가된 에폭시 접착제의 접착특성에 대하여 고찰하였다. 실리카의 표면처리는 실란커플링제인 <TEX>${\gamma}$</TEX>-methacryloxy propyl trimethoxy silane (MPS), <TEX>${\gamma}$</TEX>-glycidoxy propyl trimethoxy silane (GPS), 그리고 <TEX>${\gamma}$</TEX>-mercapto propyl trimethoxy silane (MCPS)을 사용하였다. 실리카 첨가 에폭시 접착제의 표면특성과 구조특성은 scanning electron microscope (SEM)과 Fourier transform infrared spectroscopy (FT-IR)을 이용하여 관찰하였으며 T-peel 시험법에 의한 접착특성은 universal testing machine (UTM)를 이용하여 분석하였다. 실란처리에 따른 실리카의 평형 확산압력, 표면자유에너지, 비표면적은 BET법을 이용한 <TEX>$N_2$</TEX>/77 K 기체 흡착을 통하여 관찰하였다. 결과로서, 에폭시 접착제의 접착박리강도는 미처리에 비해 접착제 내 실란처리된 실리카가 함유됨에 따라 증가하였다. 이러한 결과는 실란커플링제가 에폭시 접착제의 분산을 증가시키는 중요한 역할이라고 판단된다. 그리고 MCPS로 실란처리한 에폭시 접착제의 경우 GPS와 MPS에 비해 가장 우수한 접착력을 나타냄을 확인하였다. In this paper, the effect of silane-treated silicas and epoxidized soybean oil (ESBO) addition on adhesion properties of silicas-filled epoxy adhesives was examined. The silicas were treated by <TEX>${\gamma}$</TEX>-methacryloxy propyltrimethoxy silane (MPS), <TEX>${\gamma}$</TEX>-glycidoxy propyl trimethoxy silane (GPS), and <TEX>${\gamma}$</TEX>-mercapto propyl trimethoxy silane (MCPS). Surface and structural properties of the adhesives were determined by using scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). The t-peel strength of the adhesives was estimated using the universal testing machine (UTM). And, the equilibrium spreading pressure, surface free energy, and specific surface area were investigated by BET methods with <TEX>$N_2$</TEX>/77 K adsorption. As a result, the peel strength of the adhesives was increased in the presence of silane-treated silicas in the adhesives compared to that of untreated silicas. This result indicated that the silane coupling agent played an important role in improving the dispersion of silicas in epoxy adhesives. And, the adhesives treated by MCPS were superior to the others in adhesion.

Development of Poly(propylene) Superhydrophobic Surfaces by Functionalised TiO2 Nanoparticles: Effect of Solvents and Dipping Times

SummaryWe present a simple strategy for the fabrication of poly(propylene) (PP) superhydrophobic surfaces, i.e., surfaces that show water contact angle (WCA) ≥ 150° after a simple dipping process. Injection‐moulded PP samples were coated with titanium dioxide nanoparticles previously functionalised with trimethoxy propyl silane. Water, ethanol or xylene were used as solvents in the nanoparticles' suspensions. The prepared superhydrophobic surfaces were characterised by WCA, FTIR‐ATR, SEM and profilometry measurements. PP coated samples showed very low wettability, with WCAs higher than 150° when xylene was used as a solvent. The combination of increasing the surface roughness via dipping coating process plus the low surface tension of the coating produced the final superhydrophobic PP substrates.

Characterization of organo-modified bentonite sorbents: The effect of modification conditions on adsorption performance

The organic modification of a natural bentonite was evaluated using two methods: exchanging the interlayer cations by hexadecyltrimethylammonium (HDTMA) and grafting with vinyltrimethoxysilane (VTMS) and γ-methacryloyloxy propyl trimethoxysilane (TMSPMA) on montmorillonite surface. The physicochemical characterization of all materials was made by X-ray diffraction (XRD), IR spectroscopy, thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) surface area techniques. HDTMA cations and organosilanes were intercalated into the interlayer space of montmorillonite, as deduced from the increase of the basal spacing. IR spectroscopy, TGA and BET area give evidence of successful organic modification. The studies show a decrease in the IR absorption band intensity at 3465cm−1 with surfactant modification, and also a decrease of mass loss due to adsorbed water observed in two samples: the organoclay and functionalized bentonites, which are evidences of a lower interlayer hydrophilicity. The efficiency of aniline removal onto natural bentonite, organobentonite and functionalized bentonites from aqueous solutions was evaluated. Aniline sorption on natural bentonite was studied using batch experiments, XRD and IR spectroscopy. The hydrophobic surface of organobentonite and functionalized bentonites increased the retention capacity for nonionic organic substances such as aniline on bentonites. The sorption properties of modified bentonite, through different modification methods, enhanced the potential industrial applications of bentonites in water decontamination.

Surface modification of Fe2O3 nanoparticles with 3-aminopropyltrimethoxysilane (APTMS): An attempt to investigate surface treatment on surface chemistry and mechanical properties of polyurethane/Fe2O3 nanocomposites

Fe2O3 nanoparticles were modified with various amounts of 3-amino propyl trimethoxy silane (APTMS). Modified and unmodified nanoparticles were introduced into the polyurethane matrix at different concentrations. Fourier transform infrared radiation (FT-IR) and X-ray photoelectron spectrophotometer (XPS) were employed in order to investigate the APTMS grafting on the nanoparticles field emission-scanning electron microscope (FE-SEM) was utilized in order to investigate nanoparticles dispersion in the polyurethane coating matrix as well as the fracture behavior of the nanocomposites. The mechanical properties of the nanocomposites were investigated by dynamic mechanical thermal analysis (DMTA) and tensile test. The FTIR spectra and XPS analysis clearly showed that APTMS was grafted on the surface of nanoparticles successfully and formed chemical bonds with the surface. Also, surface treatment of the nanoparticles by silane resulted in the significant improvement of the mechanical properties of the polyurethane coating. The improvement was most pronounced when the nanoparticles were modified with 3gr silane/5g nanoparticles.

Thermal-responsive ion-imprinted polymer based on magnetic mesoporous silica SBA-15 for selective removal of Sr(II) from aqueous solution

Highly thermal-responsive magnetic Sr(II)-imprinted polymer (Sr(II)-TMIIP) was successfully synthesized as a potential effective adsorbent for selective removal of Sr(II) in aquatic environments. First, magnetic polyethyleneimine-loaded mesoporous SBA-15 (Fe3O4@PEI-SBA-15) was prepared via a simple polymer-mediated self-assembly method. Then, the surface of Fe3O4@PEI-SBA-15 was endowed with reactive vinyl groups through modification with 3-(methacryloyloxy)propyl trimethoxysilane (MPS). With the aid of vinyl groups, free radical polymerization of N-isopropylacrylamide (NIPAM), methacrylic acid (MAA), and N,N′-methylenebisacrylamide (BIS) in the presence of Sr(II) was performed with 2,2′-azobisisobutyronitrile (AIBN) as initiator, which provided a desired imprinted layer coating onto Fe3O4@PEI-SBA-15. The as-prepared Sr(II)-TMIIP was characterized by Fourier transmission infrared spectra (FT-IR), X-ray diffractometer (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM), UV, and N2 adsorption–desorption techniques. The results showed that the Sr(II)-TMIIP exhibited thermal stability, temperature and magnetic sensitivity (M s = 10.34 emu/g), and ordered mesoporous structure. Batch mode adsorption studies were conducted to investigate the specific binding kinetics, adsorption equilibrium, and selective recognition ability of Sr(II)-TMIIP. Adsorption equilibrium experiments showed that the adsorption amount strongly depended on temperature and reached a maximum around the lower critical solution temperature (LCST). Regeneration experiments indicated that repeated adsorption and desorption by temperature swings were possible. Compared with the nonimprinted polymer (NIP), the Sr(II)-TMIIP had good temperature response and excellent selectivity and reusability, making it possible in applying for Sr(II) separation and controlled release.

A core-shell surface magnetic molecularly imprinted polymers with fluorescence for λ-cyhalothrin selective recognition.

In this study, we report here a general protocol for making core-shell magnetic Fe3O4/SiO2-MPS/MIPs (MPS = 3-(methacryloxyl) propyl trimethoxysilane, MIPs = molecularly imprinted polymers, Fe3O4/SiO2-MPS as core, MIPs as shell) viaa surface molecular imprinting technique for optical detection of trace λ-cyhalothrin. The fluorescent molecularly imprinted polymer shell was first prepared by copolymerization of acrylamide with a small quantity of allyl fluorescein in the presence of λ-cyhalothrin to form recognition sites without doping. The magnetic Fe3O4/SiO2-MPS/MIPs exhibited paramagnetism, high fluorescence intensity, and highly selective recognition. Using fluorescence quenching as a detecting tool, Fe3O4/SiO2-MPS/MIPs were successfully applied to selectively and sensitively detect λ-cyhalothrin, and a linear relationship could be obtained covering a wide concentration range of 0-50 nM with a correlation coefficient of 0.9962 described by the Stern-Volmer equation. The experimental results of practical detection revealed that magnetic Fe3O4/SiO2-MPS/MIPs as an attractive recognition element was satisfactory for determination of trace λ-cyhalothrin in honey samples. This study, therefore, demonstrated the potential of MIPs for detection of λ-cyhalothrin in food.

Effects of geometry and temperature on mode I interlaminar fracture of filled polypropylene-elastomer nanocomposite

In this study, organically modified Na-MMT clay was used for the preparation of blend nanocomposites containing different ratios of polypropylene (PP) and ethylene propylene diene monomer (EPDM) elastomer in a twin screw extruder. Maleic-grafted PP (MAPP) was used as compatibilizer for making PP hydrophilic. Surface modification of Na-MMT was made by using amino propyl trimethoxy silane (APS) and trimethyl amine as coupling agent with surface grafting catalyst, respectively. A fracture mechanics approach has been adopted by mode I test and the effects of specimen geometry have been investigated. Increase in interlaminar fracture energy value, G c, was observed as the crack propagated through the composite, i.e. a rising ‘R-curve’ for both blend and nanocomposites. Deep fracture studies were carried out at different temperatures (−60 °C to 60 °C) using Izod impact and SENT tests. Fracture energy, fracture stress and brittle ductile transition were determined from crack initiation and propagation process, which showed significant improvement in impact and fracture energy at positive temperature. The wide-angle X-ray diffraction (XRD) patterns showed increased d-spacing of clay layers, indicating enhanced compatibility between PP and clay with the addition of maleated polypropylene (MAPP). Morphology/impact property relationships and an explanation of the toughening mechanisms were made by comparing the impact properties with scanning electron micrographs (SEMs) of fracture surfaces. The transmission electron microscopy (TEM) photomicrographs illustrated the intercalated and partially exfoliated structures of the hybrids with clay, MAPP and elastomer.

Application of EIS and salt spray tests for investigation of the anticorrosion properties of polyurethane-based nanocomposites containing Cr2O3 nanoparticles modified with 3-amino propyl trimethoxy silane

Abstract The Cr2O3 nanoparticles were modified with 3-amino propyl trimethoxy silane in order to obtain proper dispersion and increment compatibility with the polyurethane coating matrix. The nanocomposites prepared were applied on the St-37 steel substrates. The existence of 3-amino propyl trimethoxy silane on the surface of the nanoparticles was investigated by Fourier transform infrared (FTIR) spectroscopy and thermal gravimetric analysis (TGA). Dispersion of the surface modified particles in the polyurethane coating matrix was studied by a field emission-scanning electron microscope (FE-SEM). The electrochemical impedance spectroscopy (EIS) and salt spray tests were employed in order to evaluate the corrosion resistance of the polyurethane coatings. Polarization test was done in order to investigate the corrosion inhibition properties of the Cr2O3 nanoparticle on the steel surface in 3.5 wt.% NaCl solution. The adhesion strengths of the coatings were evaluated by pull-off adhesion tester before and after 120 days immersion in 3.5 wt.% NaCl solution. FT-IR and TGA analyses revealed that surface modification of the nanoparticles with 0.43 silane/5 g pigment resulted in the greatest amount of silane grafting on the surface of particles. Results obtained from FE-SEM analysis showed that the surface modified nanoparticles dispersed in the coating matrix properly. Results obtained from EIS and salt spray analyses revealed that the surface modified particles enhanced the corrosion protection performance of the polyurethane coating considerably. The improvement was more pronounced for the coating reinforced with 0.43 g silane/5 g pigment. Moreover, the adhesion loss decreased in the presence of surface modified nanoparticles with 0.43 silane/5 g pigment.

The influence of surface modification of lithium zinc phosphate pigment on corrosion inhibition of mild steel and adhesion strength of epoxy coating

In this paper, the influence of sol–gel surface modification of lithium zinc phosphate (LZP) pigment by methacryloxy propyl trimethoxy silane on corrosion inhibition, dispersion stability and adhesion strength was studied. IR spectroscopy and thermogravimetric analysis confirmed that organic functional group was successfully grafted onto the LZP surface. EIS and polarization measurements of mild steel showed an improvement in corrosion resistance for the extract of surface modified pigment in 3.5 % NaCl solution which was connected to better solubility proved by ICP-OES. The dispersion stability of the pigment in epoxy resin was found to be improved after surface modification. In addition, the adhesion strength of the epoxy coating containing surface modified pigment to mild steel after exposure to salt spray (5 % NaCl solution) was enhanced. The sol–gel surface modification had led to increase in hydrophobicity of the pigment particle surface, but simultaneously increased solubility of the pigment in water possibly due to the lower degree of agglomerates or aggregates of the pigment particles.

Surface modification of Cr2O3 nanoparticles with 3-amino propyl trimethoxy silane (APTMS). Part 1: Studying the mechanical properties of polyurethane/Cr2O3 nanocomposites

Abstract The surface of Cr 2 O 3 nanoparticles was modified with various amounts of 3-amino propyl trimethoxy silane (APTMS). Thermal gravimetric analysis (TGA), turbidimeter and Fourier transform infrared (FTIR) spectroscopy were utilized in order to investigate APTMS grafting on the nanoparticles. Then, polyurethane nanocomposites were prepared using various loadings of silane modified Cr 2 O 3 nanoparticles. The nanoparticles dispersion in the coating matrix was studied by a field emission scanning electron microscopy (FESEM). Dynamic mechanical thermal analysis (DMTA) and tensile test were utilized in order to investigate the mechanical properties of the nanocomposites. Results obtained from FTIR, TGA and turbidimeter measurements revealed that the organic functional groups of the silane were successfully grafted on the surface of the nanoparticles. The mechanical properties of the polyurethane were significantly enhanced using 2 wt% Cr 2 O 3 nanoparticles modified with 0.43 g silane/5 g pigment compared with other samples.

Micro double tapered optical fiber sensors based on the evanescent field-effect and surface modification

A double tapered optical fiber sensor based on evanescent field-effect and surface modification technology was introduced in this work. Whether the liquid and gas molecules had polarities or not, they all could be detected by the sensors modified in different silane coupling agents. At the same time, the sensing characters of the single mode optical fiber with three different tapering lengths were researched, and it came to a conclusion that the optical fiber sensor had stronger evanescent field effect and higher sensitivity when length of tapered fiber was 30mm. The functionalized tapered fibers modified by 3-aminopropyltrimethoxy silane (APTES) or 3-methylpropenylacyloxy propyltrimethoxy silane (MPAPTES), were employed to detect the polar or nonpolar molecules which had corresponding features. Further, the results of quantitative tests showed that the fiber optic sensor was sensitive to the change of the ethanol concentration and the characteristic peaks of the absorption power spectra could reach to 3–5dB.