نتایج جستجو برای: silica distribution

تعداد نتایج: 644141  

Journal: :journal of tethys 0

the takmeh-dash region comprises a wide variety of igneous bodies that have been developed from early to late neogen. the granitic rocks and related aplite apophyses have been developed along fault-dominated structures which defines a well pronounced mineralized zone. according to isotopic and fluid inclusion studies, most of the quartz-pyrite units are solution-related with some traces of cu, ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان - دانشکده مهندسی عمران 1392

abstract in aggregate, active forms of reactive silica with mineral names are sometimes associated with sand and gravel in concrete mixture. alkali hydroxides originated from alkalis in the cement or other resources form an alkaline silica gel with this reactive silica which becomes swallowed and expanded during time causing damage to concrete. there have been growing researches on alkaline r...

Journal: :international journal of nano dimension 0
tayseir mohammed abd ellateif chemical engineering department, universiti teknologi petronas, tronoh-31750, perak, malaysia saikat maitra government college of engineering and ceramic technology, kolkata-700010, india

in the present investigation surface modification of silica nanoparticles by alumina was carried out by sol-gel process. fourier transform infrared (ftir) and x-ray fluorescence (xrf) confirmed the synthesis of silica and the surface modification as alumina is anchored to silica surface. field emission scanning electron microscopy (fesem) and transmission electron microscopy (tem) investigation...

In the present investigation surface modification of silica nanoparticles by alumina was carried out by sol-gel process. Fourier transform infrared (FTIR) and X-ray fluorescence (XRF) confirmed the synthesis of silica and the surface modification as alumina is anchored to silica surface. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) investigation...

In the present investigation surface modification of silica nanoparticles by alumina was carried out by sol-gel process. Fourier transform infrared (FTIR) and X-ray fluorescence (XRF) confirmed the synthesis of silica and the surface modification as alumina is anchored to silica surface. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) investigation...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علوم پایه دامغان 1388

اخیراً استفاده از کاتالیزورها و معرف های تثبیت شده روی بسترهای جامد و شرایط بدون حلال گسترش یافته است زیرا چنین معرف هایی فرایندهای خالص سازی را تسهیل می کنند. از اینرو ما می خواهیم کاتالیزور اسیدی جامدی، ساخته شده از سولفوریک اسید جذب شده روی سیلیکاژل (h2so4-silica) وکاربرد آن در تهیه دی هیدروپیریمیدینون ها، تبدیل الکل ها به کربامات های نوع اول مربوطه و محافظت n-boc آمین ها را معرفی کنیم. تهیه ...

In this study, a polymer-silica nanocomposite using the sol-gel method was synthesized in three steps at room temperature. The nanocomposite material was formed with an organic compound (polyethylene glycol) and inorganic silica nanoparticles. Furthermore, the size and the distribution of nanoparticles in the polymer matrix were characterized by a transmission electron microscope (TEM).  In add...

Journal: :علوم و تکنولوژی پلیمر 0
مرتضی گنجایی ساری محسن محسنی یاسمن عقیلی عزالدین مهاجرانی سیامک مرادیان

in this article, hybrid organic-inorganic materials were prepared by free radical copolymerization of 2-hydroxyethyl methacrylate (hema) and 3-methacryloxy-propyltrimethoxysilane (mptms) via sol-gel process. the methoxysilane-containing copolymer precursors were synthesized at different compositions. these copolymer precursors were then hydrolyzed and condensed to produce phema-sio2 nanocomposi...

Journal: :Langmuir : the ACS journal of surfaces and colloids 2012
Lee A Fielding Oleksandr O Mykhaylyk Steven P Armes Patrick W Fowler Vikas Mittal Stephen Fitzpatrick

Many types of colloidal particles possess a core-shell morphology. In this Article, we show that, if the core and shell densities differ, this morphology leads to an inherent density distribution for particles of finite polydispersity. If the shell is denser than the core, this density distribution implies an artificial narrowing of the particle size distribution as determined by disk centrifug...

Journal: :Journal of colloid and interface science 2007
Jeongwoo Lee Chang Kook Hong Soonja Choe Sang Eun Shim

Core-polystyrene/shell-silica nanocomposite particles are synthesized by simple soap-free emulsion polymerization employing positively charged silica sol. The polymerization is initiated with conventional anionic KPS. It is found that the silica sol should be added after the initiation and nucleation of the soap-free emulsion polymerization in order to obtain colloidally stable composite partic...

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