INFLUENCE OF CHEMICAL MODIFICATION OF A BITUMINOUS COAL ON ITS BEHAVIOR DURING THERMOMECHANICAL ANALYSIS

The rheological behaviour of a Donbass bituminous coal was characteriz ed by thermomechanical analysis under high pressure (6 MPa) from ambie nt temperature up to 600 degrees C. Under these conditions the onset o f the transfer of the coal from a viscous to a viscofluid state could be determined from the thermomechanical curves in a range of temperatu re not easily accessible with classical plastometers. The softening te mperature and the activation energy of the viscous flow could also be determined. As intramolecular interactions are principally involved in the first stage of the thermoplasticity of coals, chemical modificati ons were applied to the coal by reductive alkylation and oxidation und er several conditions (Sternberg and Lazarov reactions) to modify the intermolecular association. The influence of these treatments is clear ly shown by the thermomechanical analysis.