Preparation And Characterization Of Ultrahigh Molecular Weight Polyethylene Fibers

UHMWPE(Ultra High Molecular Weight Polyethylene, UHMWPE) fiber is widely used in various industries based on its excellent mechanical properties. Although more attentions had paid to UHMWPE fiber, the quality and stability of domestic UHMWPE fiber need to be improved. Thus the study of the preparation process and the microstructure evolution mechanism of UHMWPE fiber play an important role during its preparation.Gel spinning method is the main way to industrial production preparation of UHMWPE fibers. In the industrial production process, UHMWPE is difficult to dissolve in solvent quickly and efficiently due to the high molecular weight, high viscosity and too much entangled nodes of the conventional raw material. Therefore, the conventional UHMWPE feedstock preparation required high temperature to dissolve completely. However, the high process temperature destroyed the molecular chain structure and reduced the molecular weight of UHMWPE dramatically, which greatly affect the mechanical performance of UHMWPE fiber.In this paper, in order to solve the solubility of UHMWPE, the modified UHMWPE raw material with low crystallinity and disentanglement was prepared through the Independent Intellectual Property Rights of technology which can be rapidly dissolved in solvent. This raw material laid the foundation for preparing the high mechanical performance UHMWPE fiber.In Donghua University, a small production line was used to study the industrialization research of high-performance UHMWPE fibers. In Gel spinning process, the modified UHMWPE powder with molecular weight of 4.67 million was used as raw material, the parallel experiments of the different UHMWPE powder concentrations( 6%, 7%, 8%, 9% and 10%) and the different spinning temperatures(250?, 270? and 290?) on the preparation of UHMWPE fiber properties was designed to study the mechanical performance influence of UHMWPE fibers. The optimal spinning process parameter was 8r/min of twin-screw extruder rate, 80? of the first level stretching temperature, 100 ? of the second level stretching temperature and 110 ? of the third level stretching temperature. In the small production line, when the spinning temperature was 250?, solution concentration were 6wt% and 7wt% respectively, the monofilament with highly intensity about of 42~45cN/dtex was successfully prepared, which was improved over 80% compared with the contrast sample.In Donghua University, small production line experiments shown that UHMWPE fibers with excellent mechanical properties could be prepared under low temperature, and concentration, which accumulated experience for the large volume preparation of UHMWPE fibers. In enlargement production lines of Ningbo institute of industrial tochnology, the parallelled experiments of the different solution concentrations(4%, 5%, 6% and 7%) and the different spinning temperatures(190?, 200?, 220? and 240?) were designed for the preparation of UHMWPE fiber. The results shown that when solution concentration was 4%, spinning temperature was 190? and 200? respectively, the multifilaments with high intensity of 35~37cN/dtex were prepared, and, monofilament strength reached 42~48cN/dtex. This process with the low spinning temperature not only effectively alleviated the molecular weight degradation, but also greatly reduced production costs.The structure of UHMWPE determined its excellent performance, so it was very important to expore the structure evolution of UHMWPE when it was prepared. In this paper, differential scanning calorimetry(DSC) was used to test the non-isothermal crystallization of different UHMWPE fiber prepared by the Gel-spinning, scanning electron microscope(SEM) for the surface morphology and wide-angle X-ray diffraction(WAXD) for crystallization, orientation, grain size and crystal layer spacing microstructure of UHMWPE fiber during the preparation in different stages.