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

The 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.

Automated summary

The study investigates the structure evolution of ultra-high molecular weight polyethylene (UHMWPE) fibers from different forming stages using various analytical techniques. It is found that the crystallinity and orientation degree of fibers increase with each drawing step, leading to improvements in mechanical properties. Additionally, the formation of monoclinic phase plays a crucial role in enhancing the mechanical properties during the manufacturing process.