Effect of the solvents treatment on the elastic properties of the bituminous coal

The measurements of density, velocity of ultrasonic waves at frequency of 2 .5 MHz, and dynamic elastic modulus were made for a raw and HCl-demineraliz ed bituminous coal (C-daf = 86.8%), subjected to action of selected solvent s such as methanol, tetrahydrofuran, pyridine, and ethylenediamine. It was found that the measured values were different for samples after treatment w ith solvents. Ultrasonic velocities and elastic moduli were generally found to increase after solvent treatment in both demineralized and the raw coal samples. The dependence of elastic modulus on swelling exhibited the same nature as that for polymers.