Impact of different modification methods on creep behavior of ultra-high molecular weight polyethylene fibers
Ultra-high molecular weight polyethylene(PE-UHMW)fibers are widely used in various fields due to their excel-lent properties.However,their tendency to creep under long-term load limits their broader applications.Most research on PE-UHMW fibers focuses on optimizing the creep performance of the fibers themselves,with less discussion on the creep process and behavior.Creep-resistant fiber samples with different properties through two modification methods were prepared:graphene blend-ing and branching modification.The creep behavior and corresponding mechanisms of different fibers were investigated through mechanical performance characterization,a 3-hour creep test at 40%of the breaking load,and differential scanning calorimetry(DSC)testing.Conventional fibers,PE-UHMW fibers doped with varying amounts of graphene,PE-UHMW fibers with different degrees of branching,and commercial creep-resistant fibers Dyneema DM20 were compared.It was found that both blending and branching modifications could enhance the creep resistance of PE-UHMW fibers,but they exhibit different creep behaviors and mechanisms.The addition of graphene effectively reduce the initial creep deformation of PE-UHMW fibers,particularly at a graphene content of 8%,where the creep deformation decreased by approximately 30%.However,when the graphene content exceed 8%,the initial creep deformation increase instead.The impact of branching modification on fiber creep performance mainly manifest in improving deformation resistance under constant load.Fibers with branches has a greater initial creep deformation than unmodified fibers,but their second-stage creep rate significantly decrease,showing better creep resistance.Time extrapolation of the creep curves verify the stability of modified fibers under long-term load.Graphene blending modification increase DSC endothermic peak of the fibers to above 146℃,while branched fibers exhibite three distinct endothermic peaks,indicating that branches intro-duce new microstructures.Finally,the mechanisms by which different modification methods affect the creep behavior of PE-UHMW fibers were discussed and analyzed.
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