The Preparation And Properties Of High Creep Resistance UHMWPE Fiber

Ultra High Molecular weight polyethylene fiber is a kind of high strength and high modulus fiber.Ultra High Molecular weight polyethylene（UHMWPE）fibers are produced from polyethylene（-CH₂-）_n,usually M_W>10⁶g.mol^-1.This material is chemically identical to the ordinary high-density polyethylene,with a higher molecular weight and a higher crystallinity,usually with its crystallinity exceeding 80%.Thus,UHMWPE fibers become the most ideal high-polymer material.However,its poor creep resistance performance limits its application in many fields.Therefore,it is of great significance to improve its surface properties and improve its creep resistance through chemical or physical methods.Surface modification,silane coupling agent modification and branching are effective ways to change the properties of polymer materials,for this topic with UHMWPE in spinning,UHMWPE irradiation modification,crosslinking degree,branched modification and creep resistance of UHMWPE fiber were studied in detail,and with UHMWPE as raw material,with different techniques,heat initiation and crosslinking during extrusion and hot stretching in order to improve the creep resistance of UHMWPE fiber.And through the mechanical properties test,thermal weight analysis,XRD test to explore the different modification method of modified UHMWPE tensile properties,creep properties,thermal properties and crystallization changes,to find out the best comprehensive performance spinning process parameters,and the UHMWPE fiber internal structure and creep properties in-depth research and exploration.The specific study contents and results are as follows:（1）Study on irradiation effect and creep resistance of high performance UHMWPE fiberFirst,UHMWPE powder and liquid paraffin were pre-expanded,and ultra-high molecular weight polyethylene fiber was prepared by gel spinning,pre-traction,extraction,hot traction and winding by double screw extruder.High creep resistant UHMWPE fibers were prepared by electron beam（EB）irradiation.The UHMWPE fiber samples impregnated with antioxidants were irradiated in air with an electron accelerator and then annealed.The irradiated fibers have a higher thermal decomposition temperature,smaller crystal size,and higher crosslinking degree than the initial fibers.The fiber gel content is as high as 88%,indicating that the crosslinking reaction occurs between the molecular chains in the amorphous region,which greatly reduces the slip of the molecular chains.A stable creep test method was used to obtain the creep curve of the modified fibers.The creep elongation of the radiative-crosslinked fibers was reduced by more than 30%at room temperature.In contrast to the un-modified UHMWPE fibers,the cross-linked UHMWPE fibers still showed good creep resistance at high temperatures,with an optimal absorbed dose of 100 k Gy.Moreover,the fiber radial shrinkage induced by radiation crosslinking increased the roughness of the fiber surface,further demonstrating the irradiation-induced crosslinking reaction in the fibers.The study in this chapter provides a simple modification strategy for the preparation and characterization of high creep resistance UHWMPE fibers to broaden the application range,especially for military protective products.（2）Study on silane crosslinking UHMWPE fiber and its creep propertiesUHMWPE composite fibers crosslinked with silane coupling agent（KH-590）were prepared by gel spinning process.,and the changes of various properties before and after UHMWPE fiber modification were studied in detail.For example,the crystallization behavior,mechanical properties,creep resistance,etc.The results show that the KH-590 content is between 0.5%and 2%,and the gel rate of UHMWPE fiber basically reaches saturation.The creep resistance performance of the cross-linked samples was significantly improved.When KH-590 was 2%,UHMWPE has the best creep resistance.With the increase of molecular weight and the increase of the coupling agent content,the crystallinity,thermal stability energy,and gel content of UHMWPE fibers were significantly enhanced.A variety of test methods and test enviro nment are adopted to provide some experimental basis for the modification method of ultra-high molecular weight polyethylene（UHMWPE）fiber.It is expected to provide an important reference for reducing the energy consumption of UHMWPE fiber and establishing the creep performance test method.