Phase Structural Analysis of Ultra High-Molecular Weight Polyethylene Fibers by Solid State High Resolution NMR

Abstract

ABSTRACT:BC 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.

Structural Analysis of Polyethylene Fibers by Solid State High Resolution NMR; the Distribution of 13C Spin-Lattice Relaxation Times

“…The results obtained assuming n = 3 for the components giving the crystalline signal are shown in Table I. 23 The longest Tic component reveals longer Tic value and greater fraction in UHF than in HDF. Molecules in the crystal of UHF may possibly have less mobility.…”

“…23 We measured carbon spin~lattice relaxation time (T 1 c) of the crystalline phase and found that the crystalline signal is composed of several components having different T 1 c. It was necessary to postulate the number of components for dividing the relaxation decay curve corresponding to respective ones. However, there were some difficulties to estimate the number of components having different relaxation times, because we had no idea of the number based on morphological nor dynamical model.…”

Structural transformation of ultra-high modulus and molecular weight polyethylene fibers by high-temperature wide-angle X-ray diffraction

“…20 have also been observed. 5,6 Different interpretation of these nonorthorhombic crystals has been A Scintag XDS 2000 X-ray diffractometer equipped with a high-temperature chamber was proposed, including triclinic, 5,7,8 monoclinic crystals, 9,10 or 'the oriented mobile' which resembles employed in this work. The CuKa radiation was generated at an accelerating potential of 45 kV the crystals but with higher mobility.…”

“…The CuKa radiation was generated at an accelerating potential of 45 kV the crystals but with higher mobility. 11,12 Structural transformations from the orthoand a tube current of 35 mA. The K b radiation was filtered by using a single-channel analyzer.…”

Crystallite Sizes and Lattice Distortions of Gel-Spun Ultra-High Molecular Weight Polyethylene Fibers

“…6 • 10 At either high pressure or the temperature close to its melting point, the orthorhombic crystals go through a solid-state phase transformation to the pseudohexagonal crystals. 3,4,10 The crystallite sizes and lattice distortions in UHMWPE fibers are not as well understood. The wide angle X-ray diffraction (W AXD) peak widths are known to be closely associated with crystallite sizes.…”