Temperature dependence of nuclear magnetic resonance absorption in coal

The proton magnetic resonance in the vitrain of Yūbari caking coal and its residue of pyridine extraction has been studied over the range 90 to 423°K. At lower temperature the absorption line consists of a broad component. At higher temperature this component begins to decrease rapidly in the line width and resolves into two components. This rapid narrowing of the absorption line width suggests a glass transition attributed to the molecular motion in coal. The variation of the second moment of the absorption line with temperature reflects the line width variation. From these results some information on the molecular motion and arrangement in coal have been obtained.