Influence of Ethyl Acetoacetate on the Structure and Thermal Stability of Alumina Aerogel

2015 ◽  
Vol 816 ◽  
pp. 157-162 ◽  
Author(s):  
Lin Xu ◽  
Yong Gang Jiang ◽  
Jun Zong Feng ◽  
Jian Feng
Keyword(s):  
Thermal Stability ◽  
Ethyl Acetoacetate ◽  
Sol Gel ◽  
Gelation Time ◽  
Supercritical Drying ◽  
Molar Ratio ◽  
Pure Alumina ◽  
Alumina Aerogel ◽  
Alumina Aerogels ◽  
Thermal Stability Of

Alumina aerogels were prepared from aluminum sect-butoxide via sol-gel process and supercritical drying. The influence of Ethyl acetoacetate (Etac) on the aerogel properties, microstructure, and thermal stability was systematically studied. At the same time, reaction mechanism was also investigated. The results show that, without and with Etac addition, the alumina aerogels are consisted of crystalline boehmite and amorphous network, respectively. When nEtac/nAl molar ratio is 0.01~0.15:1, Al2O3 aerogels have larger surface area (71~98 m2/g) than pure alumina aerogel (61m2/g) after heated at 1200°C, a proper ratio of Etac is helpful to increases the gelation time and stability of alumina sol, and is useful to improve the thermal stability of Al2O3 aerogels.

Rapid preparation process, structure and thermal stability of lanthanum doped alumina aerogels with a high specific surface area

RSC Advances ◽  
2016 ◽  
Vol 6 (31) ◽  
pp. 26271-26279 ◽  
Author(s):  
Jingfeng Yang ◽  
Qihua Wang ◽  
Tingmei Wang ◽  
Yongmin Liang
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Supercritical Drying ◽  
High Specific Surface Area ◽  
Rapid Preparation ◽  
Alumina Aerogels ◽  
Process Structure ◽  
Thermal Stability Of

In this study, we developed a new and rapid preparation method of alumina aerogels based on the sol–gel method and supercritical drying technique and prepared alumina aerogels with high specific surface area.

scholarly journals Impact of Spherical Anatase TiO2 Nanoparticles on Thermal Properties of Polypropylene Resin

2021 ◽  
Author(s):  
Ahlem Bendaoued ◽  
Mouna Messaoud ◽  
Omar Harzallah ◽  
Sophie Bistac ◽  
Rached Salhi
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
Sol Gel ◽  
Thermal Characterization ◽  
Degree Of Crystallinity ◽  
Molar Ratio ◽  
Excellent Thermal Stability ◽  
Energy Applications ◽  
Production Of Hydrogen ◽  
Thermal Stability Of

Abstract Ceramics nanometric reinforced polymer composite is a significant material for catalysis, solar cells, production of hydrogen and energy applications, etc. In order to take benefit from the interesting mechanical properties and thermal stability of TiO2, these ceramic nanomaterials was synthesized by the Sol-Gel process in attempt to study the thermal stability, structure, and morphology of the resulting nanoparticles powders. The obtained results revealed that, the sphere is composed of 20-30 nm nanoparticles with excellent thermal stability of nano-TiO2. This work focused on the thermal characterization and the study of nanocomposite xWt. %TiO2/PP (x=0, 2.5, 5, 7.5 mol%). In this study, the obtained results revealed that the molar ratio of TiO2 influences the final thermal stability and degree of crystallinity of the composite. It was found that the use of TiO2 seems to be an effective and very promising way to increase the thermal properties of the resulting composite. The greatest degree of crystallinity (54.80%) and thermal degradation stability are obtained for composite reinforced by 7.5Wt. %TiO2.

scholarly journals Synthesis and photocatalytic properties of Sn–TiO2 nanomaterials

2020 ◽  
Vol 10 (01n02) ◽  
pp. 2060018
Author(s):  
E. M. Bayan ◽  
T. G. Lupeiko ◽  
L. E. Pustovaya ◽  
M. G. Volkova
Keyword(s):  
Phase Transition ◽  
Thermal Stability ◽  
Sol Gel ◽  
Rutile Phase ◽  
Photocatalytic Properties ◽  
Light Activation ◽  
X Ray ◽  
Tio2 Nanomaterials ◽  
Visible Light Activation ◽  
Thermal Stability Of

Sn-doped TiO2 nanomaterials were synthesized by sol–gel method. It was shown the phase compositions and phase transitions change with the introduction of different tin amounts (0.5–20[Formula: see text]mol.%). X-ray powder diffraction was used to study the effect of different tin amounts on the anatase–rutile phase transition. It was found that the introduction of ions increases the thermal stability of anatase modifications. The material’s photocatalytic activity was studied in reaction with a model pollutant (methylene blue) photodegradation under UV and visible light activation. The best photocatalytic properties were shown for material, which contains 5[Formula: see text]mol.% of Sn.

Thermal stability of europium(III) chelate encapsulated by sol–gel glass

2009 ◽  
Vol 480 (2) ◽  
pp. 908-911 ◽  
Author(s):  
E. Kin ◽  
T. Fukuda ◽  
S. Yamauchi ◽  
Z. Honda ◽  
H. Ohara ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Sol Gel ◽  
Thermal Stability Of

Fabrication of Carbon Aerogels

2006 ◽  
Vol 11-12 ◽  
pp. 19-22 ◽  
Author(s):  
Y.N. Feng ◽  
Lei Miao ◽  
Yong Ge Cao ◽  
T. Nishi ◽  
Sakae Tanemura ◽  
...  
Keyword(s):  
Pore Size ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Limited Range ◽  
Molar Ratio ◽  
Carbon Aerogels ◽  
Resorcinol Formaldehyde ◽  
Catalyst Content ◽  
Fabrication Parameters ◽  
Pyrolysis Processes

RF (Resorcinol-Formaldehyde) aerogels and carbon aerogels were prepared through the sol-gel method following the routes of polymerization, gelation, supercritical drying and pyrolysis processes. The influence of fabrication parameters on the textural structure of the samples, e.g., specific surface area, pore size, and pore size distribution, etc., were systematically investigated. With a decrease in the R/F molar ratio, or an increase in the catalyst content within a limited range, the porosity of the nanostructure materials increases. The optimal temperature of pyrolysis for RF aerogel was investigated by TGA (Thermogravimetric Analysis).

scholarly journals Optimization of Polyamide Pulp-Reinforced Silica Aerogel Composites for Thermal Protection Systems

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1278
Author(s):  
Mariana E. Ghica ◽  
Cláudio M.R. Almeida ◽  
Mariana Fonseca ◽  
António Portugal ◽  
Luísa Durães
Keyword(s):  
Thermal Stability ◽  
Thermal Protection ◽  
Molar Ratio ◽  
Experimental Procedure ◽  
Thermal Protection Systems ◽  
Protection Systems ◽  
Density Values ◽  
Polyamide Fibers ◽  
First Time ◽  
Thermal Stability Of

The present work describes for the first time the preparation of silica-based aerogel composites containing tetraethoxysilane (TEOS) and vinyltrimethoxysilane (VTMS) reinforced with Kevlar® pulp. The developed system was extensively investigated, regarding its physical, morphological, thermal and mechanical features. The obtained bulk density values were satisfactory, down to 208 kg·m−3, and very good thermal properties were achieved—namely a thermal conductivity as low as 26 mW·m−1·K−1 (Hot Disk®) and thermal stability up to 550 °C. The introduction of VTMS offers a better dispersion of the polyamide fibers, as well as a higher hydrophobicity and thermal stability of the composites. The aerogels were also able to withstand five compression-decompression cycles without significant change of their size or microstructure. A design of experiment (DOE) was performed to assess the influence of different synthesis parameters, including silica co-precursors ratio, pulp amount and the solvent/Si molar ratio on the nanocomposite properties. The data obtained from the DOE allowed us to understand the significance of each parameter, offering reliable guidelines for the adjustment of the experimental procedure in order to achieve the optimum properties of the studied aerogel composites.

scholarly journals Development of Novel Silica-Based Formulation of α-Lipoic Acid: Evaluation of Photo and Thermal Stability of the Encapsulated Drug

Pharmaceutics ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 228 ◽  
Author(s):  
Ekaterina S. Dolinina ◽  
Elizaveta Yu. Akimsheva ◽  
Elena V. Parfenyuk
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Lipoic Acid ◽  
Sol Gel ◽  
Silica Matrix ◽  
Matrix Modification ◽  
Drug Stabilization ◽  
Further Development ◽  
Kinetics Of ◽  
Thermal Stability Of

Powerful antioxidant α-lipoic acid (LA) is easily degraded under light and heating. This creates difficulties in its manufacture, storage and reduces efficiency and safety of the drug. The purpose of this work was to synthesize novel silica-based composites of LA and evaluate their ability to increase photo and thermal stability of the drug. It was assumed that the drug stabilization can be achieved due to LA-silica interactions. Therefore, the composites of LA with unmodified and organomodified silica matrixes were synthesized by sol-gel method at the synthesis pH below or above the pKa of the drug. The effects of silica matrix modification and the synthesis pH on the LA-silica interactions and kinetics of photo and thermal degradation of LA in the composites were studied. The nature of the interactions was revealed by FTIR spectroscopy. It was found that the rate of thermal degradation of the drug in the composites was significantly lower compared to free LA and mainly determined by the LA-silica interactions. However, photodegradation of LA in the composites under UV irradiation was either close to that for free drug or significantly more rapid. It was shown that kinetics of photodegradation was independent of the interactions and likely determined by physical properties of surface of the composite particles (porosity and reflectivity). The most promising composites for further development of novel silica-based formulations were identified.

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