Characterization of Structural Knot Distributions in UHMWPE Fibers

Microbeam wide-angle X-ray diffraction（WAXD） experiments were carried out at different structural knot positions of SIOC and M4 fibers of ultra-high molecular weight polyethylene（UHMWPE）. The optical microscope images revealed that SIOC fiber had bamboo-like structural knots, and M4 fiber had chaotic distribution of structural knots. WAXD patterns showed the monoclinic unit cell in the whole M4 fiber, but different lamellar orientations in the bamboo joint of SIOC fiber. In addition, small-angle X-ray scattering（SAXS） patterns confirmed that the SIOC fiber contained uniform distribution of shish structures, and differential scanning calorimetry（DSC） measurements showed that its less branched and short chains benefited the orthorhombic-hexagonal phase transformation.