Evidence for network formation during the carbonization of coal from the combination of rheometry and 1H NMR techniques

Steel, Karen M., Diaz, Miguel C., Patrick, John W. and Snape, Colin E. (2006) Evidence for network formation during the carbonization of coal from the combination of rheometry and 1H NMR techniques. Fuel, 85 12-13: 1821-1830. doi:10.1016/j.fuel.2006.01.016


Author Steel, Karen M.
Diaz, Miguel C.
Patrick, John W.
Snape, Colin E.
Title Evidence for network formation during the carbonization of coal from the combination of rheometry and 1H NMR techniques
Formatted title
Evidence for network formation during the carbonization of coal from the combination of rheometry and 1H NMR techniques
Journal name Fuel   Check publisher's open access policy
ISSN 0016-2361
1873-7153
Publication date 2006-09
Sub-type Article (original research)
DOI 10.1016/j.fuel.2006.01.016
Volume 85
Issue 12-13
Start page 1821
End page 1830
Total pages 10
Place of publication Oxford, United Kingdom
Publisher Elsevier
Language eng
Abstract High-temperature rheometry and H-1 NMR have been combined to assess the microstructural changes taking place during carbonization of a number of different coals. A linear relationship exists between the logarithm of the material's complex viscosity (eta*) and the fraction of hydrogen present in rigid structures (phi(rh)) for the resolidification region in which the material is liquid-like with small amounts of dispersed solid. The relationship is best characterized by the Arrhenius viscosity equation given by eta* = eta(0)* exp([eta]phi(rh)), where eta(0)* is the complex viscosity of the liquid medium and [eta] is the intrinsic viscosity of the resolidified material. Attempts to fit the Krieger-Dougherty suspension equation showed that the solid regions formed do not pack together like a normal suspension. Instead. it is more likely that cross-linking and cyclization reactions within the liquid medium give rise to a network structure of solid material and a characteristic gel point. The ratio of hydrogen present in rigid structures to that still present in liquid form at the gel point is approximately 2:3. The resolidified material was found to have a higher [eta] than the components of the coal that remained unsoftened, which suggests that while the unsoftened components have a fairly equant shape, the resolidified components have a much higher hydrodynamic volume. The resolidification process bears similarity with thermosetting polymer networks and the eta* measurements taken for a blend of two coals follow a common two-component polymer blending rule.
Keyword Coal
Carbonization
Viscoelasticity
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status Non-UQ

 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 9 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 10 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Fri, 10 Jul 2009, 16:08:19 EST by Dr Karen Steel on behalf of School of Chemical Engineering