SOLID-SOLID PHASE-TRANSFORMATION OF UNIAXIALLY ORIENTED N-ALKANE CRYSTALS OF HIGH-PURITY

The C-13 solid-state NMR spectrum and the spin-lattice relaxation time, T-1C, have been measured at different temperatures for a uniaxially oriented n-C27H56 crystal mat of purity 99.98%, setting the orientation axis parallel or perpendicular to the static magnetic field. On the basis of the change in the lineshape and T-1C value in the different phase A, A', and H, the molecular motions such as rapid local fluctuation and rotation about the molecular chain axis are discussed in the respective phases.