共查询到20条相似文献,搜索用时 15 毫秒
1.
Natchamon Watcharakul Sirilux Poompradub Pattarapan Prasassarakich 《Journal of Sol-Gel Science and Technology》2011,58(2):407-418
In situ silica reinforcement of natural rubber (NR) grafted with methyl methacrylate (MMA) (MMA-GNR) was achieved via the
sol–gel reaction of tetraethoxysilane (TEOS) by the use of solid rubber and latex solutions. Silica contents within the MMA-GNR
as high as 48 and 19 phr were obtained when using the solid rubber and latex solutions, respectively, under optimum conditions.
The conversion efficiency of TEOS to silica was close to 95%. The in situ formed silica MMA-GNR/NR composite vulcanizates
were prepared. MMA-GNR/NR composite vulcanizates reinforced with the in situ formed silica prepared by either method had similar
mechanical properties to each other, but a shorter cure time and higher mechanical properties than those reinforced with the
commercial silica at 9 phr. The TEM micrographs confirmed that the in situ formed silica particles were well dispersed within
the MMA-GNR/NR composite matrix, whilst the commercial silica particles showed a significant level of agglomeration and a
lower level of dispersion. 相似文献
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LinYong Song ChunLei Lin Lan Wang HaiLin Sheng YiFeng Zhou WangYan Nie 《Journal of Sol-Gel Science and Technology》2011,58(3):651-655
A new strategy to fabricate teardrop-shaped silica particles is presented. Monodispersed teardrop-like silica particles were
obtained through basic catalyzed sol–gel process of tetraethoxysilane by employed sodium polyacrylate as soft template. Increasing
the salt concentration of solution, the morphology of silica particles can transform from teardrop-like to hollow structures,
and finally formed solid particles. The morphologies of silica particles are characterized by TEM and SEM. Our finding can
be scaled up for large-scale synthesis of unusual structures of inorganic or composite materials in a predictable manner.
This study is expected to provide further understanding of the role of polyelectrolyte in the synthesis of inorganic materials
towards design of unusual architectures and functional materials. 相似文献
4.
Bharat P. Kapgate Chayan Das Amit Das Debdipta Basu Uta Reuter Gert Heinrich 《Journal of Sol-Gel Science and Technology》2012,63(3):501-509
Silica particles were generated and grown in situ by sol–gel method into rubber blends comprised of natural rubber (NR) and acrylonitrile butadiene rubber (NBR) at various blend ratios. Silica formed into rubber matrix was amorphous in nature. Amount of in situ silica increased with increase in natural rubber proportion in the blends during the sol–gel process. Morphology studies showed that the generated in situ silica were nanoparticles of different shapes and sizes mostly grown into the NR phase of the blends. In situ silica filled NR/NBR blend composites showed improvement in the mechanical and dynamic mechanical behaviors in comparison to those of the unfilled and externally filled NR/NBR blend composites. For the NR/NBR blend at 40/60 composition, in particular, the improvement was appreciable where size and dispersion of the silica particles into the rubber matrix were found to be more uniform. Dynamic mechanical analysis revealed a strong rubber–in situ silica interaction as indicated by a positive shift of the glass transition temperature of both the rubber phases in the blends. 相似文献
5.
A. Santiago A. González J. J. Iruin M. J. Fernández-Berridi L. Irusta 《Journal of Sol-Gel Science and Technology》2012,61(1):8-13
Hydrophobic silica nanoparticles were obtained by microwave assisted sol–gel method using a two-step procedure. In the first
step different size silica particles were generated from tetraethyl orthosilicate and in the second one the silica particles
were hydrophobized using hexadecyl trimethoxysilane (HDTMOS). Under microwave irradiation, high conversion degrees were obtained
at relatively short reaction times. The HDTMOS added in the second step instead of coating the silica nanoparticles generated
new ones and therefore the final product showed a bimodal size distribution. All the synthesized nanoparticles gave rise to
high water contact angles (≈150°) and low hysteresis values. 相似文献
6.
Guillermo Andrade-Espinosa Vladimir Escobar-Barrios Rene Rangel-Mendez 《Colloid and polymer science》2010,288(18):1697-1704
The synthesis and physical properties of high surface area silica xerogels obtained by a two-step sol–gel process in the absence
of supercritical conditions are reported. The hydrolysis and condensation reactions were followed by infrared spectroscopy.
The increment in the bands corresponding to silanol and hydroxyl groups suggests that the hydrolysis reaction was complete
during the first 30 min. The effect on surface area and global reaction time under various reaction conditions, such as type
of alkaline catalyst and solvents, water–monomer and solvent–monomer molar ratios, was also studied. The obtained results
suggest that surface area was increased using 3-aminopropyltriethoxysilane as catalyst. The use of isopropyl alcohol as solvent
promotes the reduction of the capillary stress, giving a well-structured xerogel. As a conclusion, with H2O/i-PrOH/TEOS in a molar ratio of 10:4:1, it was possible to obtain silica xerogels with surface areas about 1,240 m2/g. Such surface areas are comparable with those obtained under supercritical conditions (aerogels), and higher than those
xerogels conventionally obtained under normal condition (500–800 m2/g). 相似文献
7.
Cristina Lavinia Nistor Dan Donescu Alain Perichaud Wael Ballout Marius Ghiurea 《Journal of Sol-Gel Science and Technology》2011,57(2):164-171
The sol–gel synthesis strategies combined with the templated growth of organic–inorganic hybrid networks provide access to
an immense new area of innovative multi-functional advanced materials. One possible way to prepare such new advanced materials
is to encapsulate liquid active agents (such as monomers, dyes, catalysts and hardeners) in microcapsules. Silica microcapsules
of tetraethylortosilicate (TEOS) and 3-(trimethoxysilyl)propyl methacrylate (MPTS) were prepared in a precursor-monomer/NH4OH water microemulsion system. Trimethylolpropane triacrylate (TMPTA)—a trifunctional monomer useful in manufacturing of coatings,
inks and adhesives—and a corresponding photoinitiator (DAROCUR 1173) were entrapped inside the obtained microcapsules. MPTS
was used to increase compatibility between TMPTA and the sol–gel precursors. As stability agent we added a “home made” product
resulted from functionalization of poly (ethylene glycol) methyl ether (MPEG) with (3-isocyanatopropyl) triethoxysilane (NCOTEOS).
Were obtained microcapsules containing incorporated monomer and having average particle size in range of 0.5–50 μm. Thermal
analysis, morphology study and the increase of the silica microcapsules average diameter, measured by DLS technique confirm
the monomer encapsulation. 相似文献
8.
Zhijie Chen Liu Yang Yingjie Yan Dongming Qi Zhihai Cao 《Colloid and polymer science》2014,292(7):1585-1597
Silica capsules were prepared via a sol–gel process using tetraethyl orthosilicate (TEOS) in inverse miniemulsions under highly acidic conditions (pH?<?2). Formation of silica capsules under acidic conditions proceeded via internal phase separation of silica species in the droplets. This mechanism is different from the well-known interfacial reaction mechanism for most syntheses of silica capsules. The driving force for the formation of capsules was the interaction between silica species and cetyltrimethylammonium bromide (CTAB) as well as between silica species and the hydrophilic block of the block copolymer surfactant, poly(ethylene-co-butylene)-b-poly(ethylene oxide) (P(E/B)-PEO). The effects of synthetic parameters on the particle morphology and size were systematically investigated in terms of the reaction time, amount of TEOS, CTAB, P(E/B)-PEO, and hydrochloric acid concentration, as well as addition of ethanol. 相似文献
9.
Jiang Chi Liu Weiqu Yang Maiping He Sha Xie Yankun Wang Zhengfang 《Journal of Sol-Gel Science and Technology》2018,87(2):455-463
Journal of Sol-Gel Science and Technology - Superhydrophobic coatings were successfully fabricated on cotton textiles through a simple one-step sol–gel process. A fluorinated copolymer... 相似文献
10.
Z. Altıntaş E. Çakmakçı M. V. Kahraman N. K. Apohan A. Güngör 《Journal of Sol-Gel Science and Technology》2011,58(3):612-618
Photocurable silica-titania hybrid coatings were prepared through an anhydrous sol–gel process. Moreover, test samples were
prepared by the addition of definite ratios of fluoro acrylate oligomers into the formulations to manage the optical properties
of transmitted light. Formulations were applied to corona-treated polycarbonate substrates. Upon adding the inorganic component
to the coating material, thermal, mechanical, and other properties, such as hardness, gloss, contact angle, and flame resistance
were improved. The photocured hybrid films showed an increase in the refractive index with increasing the titanium tetraisopropoxide
content. As expected, a decrease was observed in the refractive index of the coatings with the incorporation of fluoro acrylate
resin. The surface morphology of the hybrid films was characterized by ESEM analysis. In addition the chemical composition
of the surface of the coatings was identified by ESEM–EDS technique. ESEM studies indicated that inorganic particles were
dispersed homogenously throughout the organic matrix. 相似文献
11.
Jun Qian Huagui Zhang Guangchun Cheng Zhijuan Huang Shuaiying Dang Yongshen Xu 《Journal of Sol-Gel Science and Technology》2010,56(3):300-309
This paper presented a novel approach to prepare PP/silica nanocomposites. First, PPw-g-KH570 (γ-methacryloxypropyl trimethoxysilane) was obtained by pre-irradiation grafting method and characterized by FTIR and TGA. Then
the non-aqueous sol–gel gelation kinetics of TEOS (tetraethoxysilane)-formic acid system in xylene was researched. Subsequently
PPw/silica hybrid was obtained by in situ non-aqueous sol–gel reaction of TEOS in the presence of PPw-g-KH570 solution in xylene. Finally PP/silica nanocomposites were prepared by blending of PP matrix and PPw/silica hybrid.
The mechanism of in situ formed PPw/silica hybrid was proposed. The morphology of PPw/silica hybrid and microstructures of
PP/silica nanocomposites were characterized by TEM and SEM. The mechanical and thermal properties of PP/silica nanocomposites
were also well studied by tensile tests and DSC. It was showed that the nanosilica particles were well dispersed in PPw/silica
hybrid with the aid of grafting KH570 due to co-condensation by grafted KH570 and TEOS. PPw/silica hybrid was well dispersed
in PP matrix with good compatibility and strong interactions. The resulted PP/silica nanocomposites possessed better performance
than that of pure PP matrix. 相似文献
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Herein, addition reaction occurred between glycidol and partially hydrolyzed Ti4+ complexes provides a opportunity to obtain dry anatase nanopowder with high redispersity in water. This property is considered to be originated from the two OH groups located in the two ends of glycidol resulted chlorinated propandiol molecules. In aqueous solution, the two OH groups are respectively connected with particle surface and external free water by the formation of hydrogen bonds, resulting in high water redispersity of nanoparticles. Due to the much less amount of chlorinated propandiol molecules than adsorbed molecule water on particle, the wide space between organic molecules facilitates the mutual physical surface touch of individual particles to form hydrogen bond between them. A novel property is then obtained for surface modified titania nanoparticles, which is the gelation of redispered nanoparticles in aqueous solution. 相似文献
14.
High-quality cubic MCM-48 is successfully synthesized using a new silica source known as silatrane and cetyltrimethylammonium
bromide (CTAB) as the structure-directing agent via sol–gel process. The effects of synthesis parameters, viz. crystallization
temperature, crystallization time, surfactant concentration, quantity of NaOH, and silica source, on the product structure
are investigated. The synthesized samples are characterized using X-ray diffractometer (XRD), N2 adsorption–desorption isotherms, and electron microscopy. Optimally, this product is synthesized from samples crystallized
at 140°C for 16 h with a CTAB/SiO2 ratio of 0.3 and NaOH/SiO2 ratio of 0.5. The XRD result exhibits a well-resolved pattern, corresponding to the Ia3d space group of MCM-48. The BET surface area of this product is as high as 1,300 m2/g with a narrow pore-size distribution of 2.86 nm. The scanning electron microscopic (SEM) images also show the truncated
octahedral shape and well-ordered pore system of MCM-48 particles. 相似文献
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Hasan Guleryuz Ingeborg Kaus Claudine Filiàtre Tor Grande Mari-Ann Einarsrud 《Journal of Sol-Gel Science and Technology》2010,54(2):249-257
Deposition of silica thin films on silicon wafer was investigated by in situ mass measurements with a microbalance configured
for dip coating. Mass change was recorded with respect to deposition time when the substrate was fully immersed in the silica
sol. Mass gain during deposition was higher than predicted from monolayer coverage of silica nano particles. This implied
that deposition was facilitated by gelling of the nanoparticles on the substrate. The rate of deposition was enhanced by increasing
the particle concentration in the sol and by decreasing the particle size from 12 to 5 nm. Increasing the salt concentration
of the silica sol at constant pH enhanced the deposition of the silica particles. Reducing the pH of the sol from 10 to 6
decreased the deposition rate due to aggregation of the primary silica particles. 相似文献
17.
M. A. S. Pedroso M. L. Dias C. Azuma C. G. Mothé 《Colloid and polymer science》2000,278(12):1180-1186
This study focused on the preparation of a hydrocarbon dispersion of nanospherical silica using tetraethoxysilane homopolymerization
by a sol–gel process catalyzed by NH4OH in ethanol. The silica surface was rendered hydrophobic by the introduction of trimethylchlorosilane or trimethylethoxysilane
as a terminator. Organophilic particles with diameters in the range 10–130 nm were obtained under controlled conditions. Nevertheless,
the organophilic fraction dispersed in hexane was not greater than 62%. The homopolymerization reaction time was directly
related to the particle size and, in some cases, its insolubility. High terminator concentration and low termination temperature
favored the increase in the number of organophilic particles. The chlorine-containing terminator was more efficient in promoting
the production of hydrocarbon hydrophobic nanospheres.
Received: 21 February 2000/Accepted: 21 June 2000 相似文献
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