Carbon‐13 NMR studies of local dynamics in polymer solutions and melts

Abstract

AbstractCarbon‐13 spin‐lattice relaxation time measurements have been performed at two experimental frequencies on a series of amorphous polymers in the bulk state at temperatures well above the glass‐transition temperatures and in solution. The high experimental values of the T1 minimum as a function of temperature cannot be accounted for only by the specific orientation autocorrelation functions developed for polymers. They indicate the existence of an additional fast anisotropic motion, which we have assigned to librations of limited but significant extent of the internuclear CH vectors about their rest position. Moreover, in most cases, the temperature dependence of the segmental motions proves that they are involved in the glass‐rubber transition phenomena.