scholarly journals Synthesis and Characterization of Silicate Gel by using Sol-gel Process: Experiments and DFT calculations

2020 ◽  
Vol 9 (6) ◽  
pp. 411-421
Author(s):  
Hassan Chaair ◽  
Anas Driouich ◽  
Safae El alami El hassani ◽  
Fatimazahra Chajri ◽  
Ouafae Britel ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Sodium Silicate ◽  
Density Functional ◽  
Sol Gel ◽  
Silica Content ◽  
Reaction Products ◽  
Conceptual Density Functional Theory ◽  
Reactivity Indexes ◽  
Sol Gel Process ◽  
Reversible Gel

The synthesis of geopolymers requires the formation of an irreversible gel. This gel is produced by the sol-gel process using sodium silicate and hydrochloric acid reagents. On the one hand, the experimental study of the gelling reaction shows that for concentrations of hydrochloric acid varying between 0.5-2.0 mol/L and concentration of sodium silicate varying between 1.0-6.0 mol/L, three reaction products are obtained. The first product is a clear solution, the second product is a reversible gel, and the last product is an irreversible gel. The products obtained are characterized by SEM, X-Ray Diffraction, FTIR spectroscopy and EDS Spectroscopy techniques. The microstructural analyzes of the two gels revealed that these obtained solids are almost similar whereas the structural and elementary analyzes show that the silica content in the irreversible gel is higher than the silica content in the reversible gel. On the other hand, the theoretical study of the reactivity of gelling, defined via the conceptual density functional theory (CDFT) combined with functional B3LYP function with a 6-31G base (d). They are allowed us to define the global and local reactivity indexes of two reagents, sodium silicate and hydrochloric acid.

Synthesis and bioactivity assessment of high silica content quaternary glasses with Ca: P ratios of 1.5 and 1.67, made by a rapid sol-gel process

2017 ◽  
Vol 106 (2) ◽  
pp. 510-520 ◽  
Author(s):  
Basam A. E. Ben-Arfa ◽  
Hugo R. Fernandes ◽  
Isabel M. Miranda Salvado ◽  
José M. F. Ferreira ◽  
Robert C. Pullar
Keyword(s):  
Sol Gel ◽  
Silica Content ◽  
High Silica Content ◽  
Sol Gel Process ◽  
High Silica

A novel bulk sol-gel process to prepare monolithic silica materials

1999 ◽  
Vol 14 (10) ◽  
pp. 4098-4102 ◽  
Author(s):  
Ce Wang ◽  
Yahong Zhang ◽  
Yunfeng Lu ◽  
Yen Wei
Keyword(s):  
Sol Gel ◽  
Silica Content ◽  
Monolithic Silica ◽  
Nonpolar Solvents ◽  
Sol Gel Process ◽  
Silica Materials ◽  
High Silica ◽  
Acid Catalyzed ◽  
Carbonate Salts ◽  
Hydrolysis Of

A bulk sol-gel process has been developed to prepare monolithic silica materials at room temperature. The process involves an acid-catalyzed hydrolysis of tetraethyl orthosilicate in tetrahydrofuran containing aqueous HC1 catalyst, followed by neutralization with carbonate salts, extraction with aliphatic nonpolar solvents, molding, gelation, and drying. This method shortens the processing time from weeks for the conventional sol-gel process to several days. The silica objects prepared from the process are transparent, crack-free, and of relatively low volume shrinkage (e.g., 52%) and high silica content (e.g., 82%).

Preparation of Sodium Silicate–Based Aerogels Using a Two‐Step Sol–Gel Process and Ambient Pressure Drying

2019 ◽  
Vol 387 (1) ◽  
pp. 1800226 ◽  
Author(s):  
Uzma K. H. Bangi ◽  
Shivani S. Pandit ◽  
Dhanashri B. Bagal ◽  
Hyung‐Ho Park
Keyword(s):  
Sodium Silicate ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Ambient Pressure Drying ◽  
Sol Gel Process

Preparation and Characterization of Polyimide-Silica Nanocomposites by Sol-Gel Process

2006 ◽  
Vol 111 ◽  
pp. 111-114 ◽  
Author(s):  
Yao Yi Cheng ◽  
Kun Chang Chuang
Keyword(s):  
Sol Gel ◽  
Amic Acid ◽  
Silica Content ◽  
Nano Particles ◽  
Hybrid Thin Film ◽  
Silica Nanocomposites ◽  
Sol Gel Process ◽  
Tetracarboxylic Dianhydride

Polyimide (PI)-based nanocomposites were prepared by the in-situ generation of organic silica nano-particles through a sol-gel process, combined with spin coating and multi-step curing process. In this study, silica nano-particles were introduced into the PI matrix to promote its thermal properties. Nanometer-scale composites were successfully obtained from poly(amic acid) (PAA) mixture loaded with silica. 3,3’,4,4’- Biphenyl tetracarboxylic dianhydride (BPDA) and p-phenylenediamine (p-PDA) were employed to synthesize the PAA precursor. The hybrid thin film was prepared from aminoalkoxysilane-capped PAA and tetraethoxysilane (TEOS). In this work, we investigated the effect of coupling agent, 3-aminopropyltriethoxysilane (APrTEOS). The TGA results indicate that the thermal stability of the nanocomposites can be enhanced as silica content increases. Without the incorporation of APrTEOS, less improvement can be achieved.

Influence of the silica content in SPEEK–silica membranes prepared from the sol–gel process of polyethoxysiloxane: Morphology and proton mobility

2009 ◽  
Vol 337 (1-2) ◽  
pp. 125-135 ◽  
Author(s):  
Irene Colicchio ◽  
Dan E. Demco ◽  
Maria Baias ◽  
Helmut Keul ◽  
Martin Moeller
Keyword(s):  
Sol Gel ◽  
Silica Content ◽  
Proton Mobility ◽  
Silica Membranes ◽  
Sol Gel Process

Physical properties of sodium silicate based silica aerogels prepared by single step sol–gel process dried at ambient pressure

2009 ◽  
Vol 476 (1-2) ◽  
pp. 397-402 ◽  
Author(s):  
Jyoti L. Gurav ◽  
A. Venkateswara Rao ◽  
A. Parvathy Rao ◽  
D.Y. Nadargi ◽  
S.D. Bhagat
Keyword(s):  
Physical Properties ◽  
Sodium Silicate ◽  
Ambient Pressure ◽  
Sol Gel ◽  
Silica Aerogels ◽  
Single Step ◽  
Sol Gel Process

“Abrasion Resistant Coatings with Ultraviolet Absorption, via sol-gel dipping method.“

2004 ◽  
Vol 847 ◽  
Author(s):  
Naiming Arfsten ◽  
Manuel A. Alvarez
Keyword(s):  
Chemical Stability ◽  
Sol Gel ◽  
Glycidyl Ether ◽  
Dip Coating ◽  
Epoxy Compound ◽  
Cross Linking ◽  
Reaction Products ◽  
Film Hardness ◽  
Sol Gel Process ◽  
Uv Range

ABSTRACTMulti-cpoxy functional - glycidyl ether is used as a cross-linking epoxy compound between modified 22'44'-tetrahydroxybenzophenone and silicone molecules. The adduct reaction products, as effective abrasion resistant coatings and yet reactive in the sol gel process, are formulated into the colloidal based polysiloxane resin as an essential part of the solution for dip coating sheets. Such coatings incorporate ultraviolet radiation selection or absorbing compounds with superb chemical stability and mechanical strength for coatings on substrates such as glass. The hardness of these coatings was measured at 6H following ASTM (D-3363) film hardness by pencil test. The resulting coatings were exposed to ultraviolet (UV-A) radiation during a time greater than 600 hours. The exposed samples still maintain excellent absorption in the UV range.

scholarly journals Microstructure and Thermomechanical Properties of Polyimide-Silica Nanocomposites

2006 ◽  
Vol 2006 ◽  
pp. 1-9 ◽  
Author(s):  
A. Al Arbash ◽  
Z. Ahmad ◽  
F. Al-Sagheer ◽  
A. A. M. Ali
Keyword(s):  
Sol Gel ◽  
Thermomechanical Properties ◽  
Silica Content ◽  
Hydroxyl Groups ◽  
Thermal Coefficient ◽  
Silica Network ◽  
Interphase Interaction ◽  
Silica Nanocomposites ◽  
Sol Gel Process ◽  
Alkoxy Groups

Novel polyimide-silica nanocomposites with interphase chemical bonding have been prepared using the sol-gel process. The morphology, thermal and mechanical properties were studied as a function of silica content and compared with the similar composites having no interphase interaction. The polyimide precursors, polyamic acids (PAAs) with or without pendant hydroxyl groups were prepared from the reaction of pyromellitic dianhydride with a mixture of oxydianiline and 1,3 phenylenediamine or 2,4-diminophenol in dimethylacetamide. The PAA with pendant hydroxyl groups was reacted with isocyanatopropyltriethoxysilane to produce alkoxy groups on the chain. The reinforcement of PAA matrices with or without alkoxy groups on the chain was carried out by mixing appropriate amount of tetraethoxysilane (TEOS) and carrying out its hydrolysis and condensation in a sol-gel process. Thin hybrid films were imidized by successive heating up to 300C∘. The presence of alkoxy groups on the polymer chain and their cocondensation with TEOS developed the silica network which was interconnected chemically with the polyimide matrix. SEM studies show a drastic decrease in the silica particle size in the chemically bonded system. Higher thermal stability and mechanical strength, improved transparency, and low values of thermal coefficient of expansion were observed in case of chemically bonded composites.

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