Structure-property analysis for gel-spun, ultrahigh molecular mass polyethylene fibers

Abstract

Abstract The structures of four gel-spun, ultrahigh molecular mass polyethylene fibers have been studied with the techniques of full-pattern x-ray diffraction, small-angle x-ray scattering, powder x-ray diffraction, solid-state 13C nuclear magnetic resonance, differential scanning calorimetry, and optical microscopy. A high molecular mass polyethylene fiber is also studied for comparison. At room temperature these fibers show mainly the common orthorhombic crystals and a small amount of monoclinic crystals in addition to an intermediate, oriented phase and the amorphous phase. The structure parameters of the orthorhombic phase change slightly with fiber processing history. The chains of the intermediate phase have largely a trans-conformation and are oriented preferentially parallel to the fiber axis, but are disordered laterally. The mobility (correlation time) of the carbon atoms of the intermediate phase is higher than that of the crystalline phase by 2 orders of magnitude, but lower than that of the a...