PHASE STRUCTURAL-ANALYSIS OF ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE FIBERS BY SOLID-STATE HIGH-RESOLUTION NMR

13C solid state high resolution NMR spectra of ultra high-molecular weight polyethylene fibers (UHF) were measured. The main narrow line is due to orthorhombic crystalline phase (ORC). Because of the high degree of crystallinity, amorphous phase signal is observed so small as the foot of the main crystalline phase signal. The small signal of monoclinic crystal phase (MCC) can be observed at lower field than the ORC signal. Signal width of MCC peak is as narrow as ORC peak. Several kinds of relaxation parameters are measured to discuss the two crystalline and intermediate phase. The crystalline phase signal can be divided into several components according to the difference in relaxation time. The signal of highly mobile component spreads over MCC and ORC signals. This component is not a crystal but its conformation is similar to that of the crystal. It may be such as oriented amorphous. © 1990, The Society of Polymer Science, Japan. All rights reserved.