Structural evolution in carbon aerogels as a function of precursor material and pyrolysis temperature
Several organic reactions that proceed through a sol-gel transition have been identified at LLNL. The most-studied reaction involves the aqueous polycondensation of resorcinol (1,3-dihydroxybenzene) with formaldehyde. Recently, we have shown that phenol can be added to this polymerization as a comonomer. The resultant crosslinked gels are supercritically dried from carbon dioxide ({Tc}=31{degrees}C, P{sub c}=7.4 MPa) to give resorcinol-phenol-formaldehyde (RPF) aerogels. Because RPF aerogels are composed of a highly crosslinked aromatic polymer, they can be pyrolyzed in an inert atmosphere to form vitreous carbon monoliths. The resultant aerogels are black in color and no longer transparent, yet they retain the high porosity (40--98 %), ultrafine cell/pore size (< 50 nm), high surface area (600--800 m{sup 2}/g), and interconnected particle ({approximately}10 nm) morphology of their organic precursors. In this study, we examine the acoustic and mechanical properties of these materials as a function of precursor material and pyrolysis temperature.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 231318
- Report Number(s):
- UCRL-JC--123480; CONF-960401--8; ON: DE96009706
- Country of Publication:
- United States
- Language:
- English
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