A mode-coupling theory catastrophe scenario description of relaxations in semicrystalline nylons

In the conception of mode-coupling theory the liquid-glass transition is due to topological singularities (mathematical catastrophes) in a system's parameter space. It is shown that previously published dielectric relaxation data for a number of semicrystalline polymers (polyalanine, polyglycine, nylon 3 and nylon 4) exhibit the characteristic signatures for an A(4)-singularity: inflection points, linear regions in ln(omega), l/f noise regions, as well as a double minimum. Besides agreeing qualitatively with mode-coupling theory predictions, the data can also be described quantitatively with the A(4)-scenario.