Structure and properties of gel‐spun ultra‐high molecular weight polyethylene fibers obtained from industrial production line

Abstract

AbstractThe structure evolution of commercial fibers with excellent performance is always a hot research topic. In this work, we used samples obtained from different forming stages of industrial production lines with a total draw ratio of 54.5 to explore the structure–property evolution of ultra‐high molecular weight polyethylene (UHMWPE) fibers through a combination of differential scanning calorimetry, wide‐angle X‐ray diffraction, and small angle X‐ray scattering methods. The results showed that the preferential orientation of amorphous molecular chain and the crystallinity increased rapidly in predrawing process, but the mechanical properties were basically unchanged, demonstrating that this stage had little effect on mechanical properties of fibers. At first‐step drawing, the crystallinity and orientation degree increased from 68% to 81% and 0.88 to 0.97, respectively, accompanied by rapid increase in modulus and tensile strength (29.5 to 878.1 cN/dtex and 4.3 to 21.1 cN/dtex, respectively) and the formation of monoclinic phase and fibrillar crystals also happened at this stage. The content of monoclinic phase with tighter structure was increased during the second‐step and third‐step drawing, which were crucial for the continuous improving mechanical properties. In addition, the molecular schematic diagram was proposed to describe structural development of UHMWPE fibers during manufacture process.