SOME COMMENTS ON THE PAPER OF LARSEN ET-AL AND THE NATURE OF CROSS-LINKING IN COAL

In this short paper two arguments are made. First, the swelling report ed in the preceding paper cannot be due to a selective titration of hy drogen-bonding cross-links, for various reasons associated with the th ermodynamics and statistical mechanics of how these interactions are t reated. Second, in the ''liquid'' state (i.e., T > T-g) H bonds cannot be cross-links because their ''lifetimes'' or relaxation times are mu ch shorter than that of a mechanical experiment such as swelling. In o ther words, hydrogen bonds break and re-form many times during the cou rse of swelling, giving the chain segments ample time and opportunity to relax.