Structure Evolution Analysis Of UHMEPE Fiber During Processing And Its Antibacterial Modification

In recent years,ultra-high molecular weight polyethylene(UHMWPE)fibers have been widely used in the fields of national defense industry and civilian fabrics due to their high modulus,high axial tensile strength and high cut resistance.Although UHMWPE fiber has excellent mechanical properties,and the tensile strength of some commercial UHMWPE fiber products can reach more than 40 c N/dtex,but it is only 3%of the maximum theoretical value.The performance of materials is determined by its microstructure,and the change of microstructure is closely related to the processing.Therefore,research on the relationship between the processing-structure-performance has a guiding significance for the performance improvement of UHMWPE fiber.With the development of economy and society,people's awareness of health protection has gradually increased.It is hoped that traditional fiber products can have multiple functions while meeting basic requirements.Therefore,functional modification of traditional fabrics and development of a UHMWPE fabric with antibacterial function and good comfort has important economic value and social significance.First of all,the relationship between the processing-structure-performance of UHMWPE fibers obtained from different forming stages of industrial production lines was studied by online sampling methods in this article.It was found that the orientation of amorphous molecular chains and lamellae in UHMWPE fibers would be caused in the pre-drawing,extraction and drying process.The axial fine lines in fiber surface was appeared and the elongation at break was greatly reduced,but the crystallinity,tensile strength and modulus were basically unchanged.After first-stage of hot drawing,monoclinic crystals were formed in the UHMWPE fibers,and the folded-chain crystals were transformed into fibrous crystals.At the same time,the crystallinity and orientation of crystal region in fibers were rapidly increased,and the tensile strength and modulus were significantly improved,indicating that the improvement of mechanical properties may be caused by the increase in crystallinity,orientation of crystal region and the formation of fibrous crystals.After second and third-stages of hot drawing,the crystallinity of UHMWPE fiber was basically unchanged,but orientation of crystal region and mechanical properties were continuously improved,and the crystal size of monoclinic crystals were continuously decreased.It showed that the improvement of mechanical properties in fibers at this stage may be caused by the increase in orientation of crystal region and the continuous improvement of the monoclinic crystal structure.Finally,the structural evolution model was established to study the processing-structure-performance relationship of industrial UHMWPE fibers under the combined action of stress and temperature fields.Secondly,the co-deposition reaction of dopamine and polyethyleneimine was used to modify the surface of UHMWPE fiber in this paper,and Cu²⁺was fixed on the fiber surface through coordination reaction to obtain an antibacterial fabric(UHMWPE-PDA/PEI-Cu).The antibacterial fabric was characterized and analyzed through a series of methods such as SEM,ATR-FTIR,XPS.The antibacterial performance of UHMWPE-PDA/PEI-Cu was studied and the results showed that it has good antibacterial effects against E.coli and S.aureus.In addition,the antibacterial properties of UHMWPE-PDA/PEI-Cu prepared with different copper sulfate solution concentrations and reaction times were explored,and the results showed that UHMWPE-PDA/PEI-Cu obtained from copper sulfate solution with a concentration of 70 m M and a reaction time of 2 h has the best antibacterial effect against E.coli and S.aureus.In terms of antibacterial mechanism analysis,research had been carried out through Zeta potential,ICP and EPR,etc.,and the possible antibacterial mechanism of UHMWPE-PDA/PEI-Cu was inferred:the synergistic effect of static electricity and singlet oxygen(¹O₂),which can inhibit the reproduction of bacterial.