Сибирский федеральный университет

Тип публикации: статья из журнала

Год издания: 2020

Идентификатор DOI: 10.17516/1998-2836-0173

Ключевые слова: tannins, abies bark, formaldehyde, sol-gel condensation, organic and carbon xerogels, structure, thermal properties

Аннотация: Methods of organic and carbon xerogels synthesis based on the use of condensed tannins isolated from abies bark were developed. Organic gels were synthesized by sol-gel condensation of tannins with formaldehyde in a solution of ethanol in the presence of catalysts (NaOH or HCl). The final gelation products were dried by alternating low (-18 - -40 degrees C) and room temperature to obtain tanninformaldehyde (TF) xerogels. FTIR study indicates that the formation of xerogels was accompanied by crosslinking reactions mainly due to the formation of carbon-carbon and alkyl ether bonds. Using the method of thermogravimetry, it was found that organic TF xerogels are thermally stable up to a temperature of 295 degrees C and they are resistant to ignition in air at temperatures up to 600 degrees C and can be used as thermo- and fire-retardant materials. Carbon tannin-formaldehyde xerogels were obtained by carbonization of organic xerogels at 800 degrees C in an argon atmosphere. The porous structure and surface morphology of organic and carbon xerogels was studied by BET- and SEM-methods. A significant development of the specific surface area (to 483-524 m(2)/g)as a result of the organic xerogels carbonization was established. Using SEM, it was shown that in carbon gels a spatially cross-linked structure of polymer chains consisting of 5-10 nmsized globule particles forming nanometer-sized pores is retained. Methods of organic and carbon xerogels synthesis based on the use of condensed tannins isolated from abies bark were developed. Organic gels were synthesized by sol-gel condensation of tannins with formaldehyde in a solution of ethanol in the presence of catalysts (NaOH or HCl). The final gelation products were dried by alternating low (-18 – -40 °C) and room temperature to obtain tannin-formaldehyde (TF) xerogels. FTIR study indicates that the formation of xerogels was accompanied by crosslinking reactions mainly due to the formation of carbon-carbon and alkyl ether bonds. Using the method of thermogravimetry, it was found that organic TF xerogels are thermally stable up to a temperature of 295 °C and they are resistant to ignition in air at temperatures up to 600 °C and can be used as thermo- and fire-retardant materials. Carbon tannin-formaldehyde xerogels were obtained by carbonization of organic xerogels at 800 °C in an argon atmosphere. The porous structure and surface morphology of organic and carbon xerogels was studied by BET- and SEM–methods. A significant development of the specific surface area (to 483–524 m2/g)as a result of the organic xerogels carbonization was established. Using SEM, it was shown that in carbon gels a spatially cross-linked structure of polymer chains consisting of 5-10 nmsized globule particles forming nanometer-sized pores is retained. © Siberian Federal University. All rights reserved

Журнал: JOURNAL OF SIBERIAN FEDERAL UNIVERSITY-CHEMISTRY

Выпуск журнала: Vol. 13, Is. 2

Номера страниц: 175-188

ISSN журнала: 19982836

Место издания: KRASNOYARSK

Издатель: SIBERIAN FEDERAL UNIV

• Kuznetsov Boris N. (FRC Krasnoyarsk Sci Ctr SB RAS, Inst Chem & Chem Technol SB RAS, Krasnoyarsk, Russia; Siberian Fed Univ, Krasnoyarsk, Russia)
• Ivanov Ivan P. (FRC Krasnoyarsk Sci Ctr SB RAS, Inst Chem & Chem Technol SB RAS, Krasnoyarsk, Russia)
• Levdanskiy Vladimir A. (FRC Krasnoyarsk Sci Ctr SB RAS, Inst Chem & Chem Technol SB RAS, Krasnoyarsk, Russia)
• Kuznetsov Boris N. (FRC Krasnoyarsk Sci Ctr SB RAS, Inst Chem & Chem Technol SB RAS, Krasnoyarsk, Russia; Siberian Fed Univ, Krasnoyarsk, Russia)

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