STRUCTURAL-ANALYSIS OF POLYETHYLENE FIBERS BY SOLID-STATE HIGH-RESOLUTION NMR - THE DISTRIBUTION OF C-13 SPIN-LATTICE RELAXATION-TIMES

13C solid state high resolution NMR spectra of ultra high-molecular weight polyethylene fibers (UHF) and high-density polyethylene fibers (HDF) were measured at room temperature. The 13C spin-lattice relaxation decay curves for the main lines, assigned to the orthothombic crystalline phase (ORC), were composed of multiple components and analyzed by non-linear least squares method. Although it was difficult to determine the number of components, the distribution curve of T1Cs was obtained and the origin discussed in relation to the crystalline structure of the polyethylene fibers. Three component analysis gave fairly good agreement. The ambiguity of the component analysis is due to the distribution of the T1C of each component. The longest T1C component had a narrow distribution but the other components were spread over a wide range of T1C. The T1C value of the each component is shorter in HDF than in UHF. © 1990 The Society of Polymer Science, Japan.