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

The rheological behaviour of a Donbass bituminous coal was characterized by thermomechanical analysis under high pressure (6 MPa) from ambient temperature up to 600 degrees C. Under these conditions the onset of the transfer of the coal from a viscous to a viscofluid state could be determined from the thermomechanical curves in a range of temperature not easily accessible with classical plastometers. The softening temperature 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 modifications were applied to the coal by reductive alkylation and oxidation under several conditions (Sternberg and Lazarov reactions) to modify the intermolecular association. The influence of these treatments is clearly shown by the thermomechanical analysis.