The effect of high temperature sol-gel polymerization parameters on the microstructure and properties of hydrophobic phenol-formaldehyde/silica hybrid aerogels

Seraji, Mohamad Mehdi; Sameri, Ghasem; Davarpanah, Jamal; Bahramian, Ahmad Reza

doi:10.1016/j.jcis.2017.01.014

Cited by 28 publications

(10 citation statements)

References 28 publications

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“…The OH group causes the capillary and tension effect which pull the surface material during the APD step. The shrinkage was also caused by the generating of a new crosslink among near surfaces (Seraji, Seifi, and Bahramian 2015;Seraji et al 2017).…”

Section: Resultsmentioning

confidence: 99%

Influence Of Drying Time And Temperature On Zirconium-Based Material (ZBM) Properties For 99Mo/99mTc Generator Development

et al. 2018

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INFLUENCE OF DRYING TIME AND TEMPERATURE ON ZIRCONIUM-BASED MATERIAL (ZBM) PROPERTIES FOR 99Mo/99mTc GENERATOR DEVELOPMENT. Zirconium-based material (ZBM) has an important role in producing Technetium-99m (99m Tc) due to its high adsorption capacity to Molybdenum-99 (99 Mo). The adsorption capacity of the ZBM depends on the specific surface area which is influenced by several parameters in the synthesis process. This study aims to investigate the influence of drying time and temperature on the structure and specific surface area of the ZBM. Synthesis of the ZBM was carried out using zirconium chloride, 2-propanol, water and tetrahydrofuran at 75 °C, 90 °C and 120 °C and for 3 hr, 5 hr and 7 hr, respectively. Functional group and specific surface area of the ZBM was analyzed by FTIR and BET method, respectively. At the variation of drying time, the functional group pattern showed by FTIR spectra was not significantly different. The O-H group of the ZBM increased as the drying temperature decreases. At 75 and 90°C, the specific surface area increased as the function of time was increased but was decreased at 120°C. The highest surface area of the synthesized ZBM had a poor performance as a 99 Mo/ 99m Tc generator material, whereas the eluate met the required standard.

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Section: Resultsmentioning

confidence: 99%

Influence Of Drying Time And Temperature On Zirconium-Based Material (ZBM) Properties For 99Mo/99mTc Generator Development

et al. 2018

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“…The influence of thermal treatment of monoliths and aerogels on their properties is studied by many authors [31][32][33][34], however only a few works deal with the influence of thermal treatment on properties of inorganic-organic films [35][36][37]. In paper [35], the authors studied the properties of organic-inorganic thin SiO 2 films modified with polydimethysiloxane, while the given films were deposited on glass and aluminium alloy and treated at temperatures of 100, 200, 300 and 400 °C.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Treatment Temperature on Surface Properties of Inorganic-Organic Films

Papučová¹

2021

Ceramics - Silikaty

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The paper deals with the treatment temperature influence of inorganic-organic films on their surface properties. Inorganic-organic films were prepared by sol-gel method in "tetraethoxysilane -triethoxy(octyl)silane -water -nitric acid -isopropyl alcohol" system, and they were treated at temperatures of 140, 160, 180, 200 and 220 °C. The atomic force microscopy and sessile drop technique were used for characterization of film surface. The morphology, rms-roughness, and surface wettability (hydrophobicity) were evaluated. Surface free energy and its polar and dispersion component were calculated by Owens-Wendt-Rabel-Kaelble (OWRK) method, using contact angles of water and diiodomethane. On the basis of results of all studied properties, the films can be divided into two groups. The first group is represented by films prepared at temperatures of 140, 160 and 180 °C because there is the evaporation of present solvents. The second group is represented by films prepared at temperatures of 200 and 220 °C because the degradation processes of inorganic-organic components are in progress in films.

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“…Their low cost, high tensile strength, and fire‐retardant characteristics make them as a great candidate for preparation of organic aerogels. Recently, Bahramian research group has focused on the preparation and characterization of novolac type phenolic aerogels for high temperature applications 8–12 . Moreover, they reported a new sol–gel method for preparation of novolac aerogels named as solvent saturated vapor atmosphere (SSVA) 13 .…”

Section: Introductionmentioning

confidence: 99%

Microstructural properties, thermal insulation and thermal degradation behavior of boron‐containingmonolithic novolac xerogels

Seraji

Ahmad

2020

J of Applied Polymer Sci

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Enhancement of thermal stability‐insulation performance of hyper porous materials is the premier issue to design of novel porous thermal protection systems. Boron‐containing monolithic novolac xerogels (BCNXs) were synthesized using sol–gel networking of novolac resin with hexamethylenetetramine (HMTA) and boric acid at the solvent saturated vapor atmosphere (SSVA). The aim was to elucidate the effect of higher crosslinking density and thermal stable boron containing chemical bonds on the microstructure, thermal conductivity, and thermal oxidation stability of novolac xerogels. The results of FESEM and BET analysis showed that the microstructural characteristics of xerogels are significantly depend on the HMTA and boric acid concentration. The thermogravimetric results were analyzed using characteristic kinetic temperature (CKT)‐characteristic kinetic temperature range (CKTR) approximations. The effect of micromorphology of xerogels on the thermal conductivity was investigated. The effective thermal conductivity of samples were in the range of 0.031–0.048 W/m K.

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The effect of high temperature sol-gel polymerization parameters on the microstructure and properties of hydrophobic phenol-formaldehyde/silica hybrid aerogels

Cited by 28 publications

References 28 publications

Influence Of Drying Time And Temperature On Zirconium-Based Material (ZBM) Properties For 99Mo/99mTc Generator Development

Influence Of Drying Time And Temperature On Zirconium-Based Material (ZBM) Properties For 99Mo/99mTc Generator Development

The Influence of Treatment Temperature on Surface Properties of Inorganic-Organic Films

Microstructural properties, thermal insulation and thermal degradation behavior of boron‐containingmonolithic novolac xerogels

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