Laskowski, Jessica and Milow, Barbara and Ratke, Lorenz (2014) Subcritically dried resorcinol-formaldehyde aerogels from a base-acid catalyzed synthesis route. Microporous and Mesoporous Materials, 197, pp. 308-315. Elsevier. doi: 10.1016/j.micromeso.2014.06.031. ISSN 1387-1811.
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Abstract
Resorcinol-formaldehyde (RF) aerogels are prepared from a newly developed base-acid catalyzed sol-gel synthesis route. RF-gels synthesized are nanostructured and can be dried under ambient conditions without significant shrinkage. The sol-gel reaction of resorcinol (R) and formaldehyde (F) in water (W) (R/F = 0.7, R/W = 0.04) is initially catalyzed by Na2CO3 with a molar ratio of resorcinol to catalyst (R/C) of 100. After a specified time after starting the reaction (1-3 h), citric acid (1 M, 4–20 vol.-%) is added which initiates the acid catalyzed step and causes a spontaneous gelation. The time of change in pH value by adding acid is of great importance and influences the structure and properties of the material. RF-aerogels consisting of small particles much smaller than 100 nm are prepared by applying a long base catalyzed step. Particle size, density, thermal conductivity and surface area are basically independent of the amount of citric acid, but this parameter influences the mechanical resistance. A theoretical model is used to describe the time dependence of catalyst change in the sol-gel process.
Item URL in elib: | https://elib.dlr.de/90065/ | ||||||||||||
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Document Type: | Article | ||||||||||||
Additional Information: | referiert | ||||||||||||
Title: | Subcritically dried resorcinol-formaldehyde aerogels from a base-acid catalyzed synthesis route | ||||||||||||
Authors: |
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Date: | 2014 | ||||||||||||
Journal or Publication Title: | Microporous and Mesoporous Materials | ||||||||||||
Refereed publication: | Yes | ||||||||||||
Open Access: | No | ||||||||||||
Gold Open Access: | No | ||||||||||||
In SCOPUS: | Yes | ||||||||||||
In ISI Web of Science: | Yes | ||||||||||||
Volume: | 197 | ||||||||||||
DOI: | 10.1016/j.micromeso.2014.06.031 | ||||||||||||
Page Range: | pp. 308-315 | ||||||||||||
Publisher: | Elsevier | ||||||||||||
ISSN: | 1387-1811 | ||||||||||||
Status: | Published | ||||||||||||
Keywords: | Sol-gel; resorcinol-formaldehyde aerogel; base-acid catalyzed; subcritical drying | ||||||||||||
HGF - Research field: | Aeronautics, Space and Transport | ||||||||||||
HGF - Program: | Transport | ||||||||||||
HGF - Program Themes: | Terrestrial Vehicles (old) | ||||||||||||
DLR - Research area: | Transport | ||||||||||||
DLR - Program: | V BF - Bodengebundene Fahrzeuge | ||||||||||||
DLR - Research theme (Project): | V - Neuartige Fahrzeugkonzepte und -strukturen (old) | ||||||||||||
Location: | Köln-Porz | ||||||||||||
Institutes and Institutions: | Institute of Materials Research > Aerogele | ||||||||||||
Deposited By: | Laskowski, Jessica | ||||||||||||
Deposited On: | 27 Oct 2014 10:30 | ||||||||||||
Last Modified: | 30 May 2019 22:07 |
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