Preparation Of Electrospun Ultrafine Ultrahigh Molecular Weight Polyethlene Fiber And The Study Of Reinforcement Technologies

Ultrahigh molecular weight polyethylene (UHMWPE) fiber is a third-generationhigh-performance fiber. It has outstanding mechanical property and excellent comprehensiveperformance. However, it’s a big challenge in manufacturing ultrafine UHMWPE fibers withgel spinning, compaction and sintering, screw extruding methods due to the tendency oftangling of the ultralong molecular chains. With the decrease of the fibers diameter, theinternal structure defects of fibers reduces, and hence the performance of fibers becomesbetter. Therefore, refining fibers is very important to improve the fibers performance.Electrospinning is a simple and powerful method for fabricating very thin polymer fibers withsuperior structure and performance. Therefore, in this paper, ultrafine UHMWPE fibers werefabricated from electrospinning. In order to improve the tensile properteis of the electrospunUHMWPE fibers, three reinforcement methds including drawing, ultrasonic vibration andCarbon nanotubes reinforcements have been studied. The results are as followed:(1) Electrospinning was employed to fabricate ultrafine UHMWPE fibers by usingparaffin as the solvent, p-xylene as the extractant and added antioxidant B225in theUHMWPE solutions. A high-voltage of13kV was applied to the syringe needle, the volumeflow rate was0.6ml/h, and the distance between the needle and the collector was25cm. Thescanning electrospinning microscopy (SEM) pictures showed that, the diameter of fibers wasin the range of570～1090nm, and the higher concentration of the UHMWPE solutionresulted in a thicker fiber diameter. X-ray diffraction (XRD) and Fourier transform infraredspectroscopy (FTIR) analysis confirmed that the chemical structure of UHMWPE was unchanged.Tensile testing results of the fiber bundles showed that, the specific stress of fiber bundlesfrom1.0wt%solution reached3.88cN/den, the specific stress of fiber bundles from0.5wt%solution was the lowest, only1.91cN/den.(2) Drawing reinforcement study showed that the cross-section of the drawn fibers wasflat, and the fracture pattern was ductile. The orthogonal experiments results of drawingreinforcement showed that the factors influence the1.0wt%UHMWPE fiber bundles specificstress in the sequence of drawing ratio＞drawing temperature＞extraction temperature. Bythe analysis of the orthogonal experiment results can conclude that the reasonable tensileproperties test condition was the extraction temperature50℃, drawing temperature90℃, anddrawing ratio4, resulting in the increasement of the specific stress of fiber bundles from6.61cN/den to12.67cN/den. the factors influence the1.5wt%UHMWPE fiber bundlesspecific stress in the sequence of drawing ratio＞extraction temperature＞drawingtemperature and the reasonable tensile properties test condition was the extractiontemperature50℃, drawing temperature100℃, and drawing ratio4, resulting in the increasement of the specific stress from8.03cN/den to12.84cN/den.(3) Ultrasonic vibration reinforcement study showed that, after10min vibrationtreatment, the diameter of the fibers fabricated from1.5wt%、1.75wt%and2.0wt%UHMWPE solutions decreased from1088nm、2487nm and3577nm to482nm、772nm and1169nm, respectively.XRD analysis of the fibers electrospun from2.0wt%solution indicatedthat ultrasonic vibration improved the crystallinity of of UHMWPE fiberswith the increasingvibration time. Tensile testing results of the fiber bundles from1.75wt%and2.0wt%UHMWPE solutions showed that, after10min treatment, the specific stress of the fiberbundles increased from3.22cN/den and3.69cN/den to6.17cN/den and6.90cN/den,respectively. However, because of the slight degradation of1.5wt%solution, the specificstress of the fiber bundles decreased from8.81cN/den to5.12cN/den. The above resultsshowed that, ultrasonic vibration reinforcement was more suitable for the solutions of higherconcentration.(4) Multi-walled carbon nanotubes (MWNTs) reinforcement experiment showed that,UHMWPE/MWNTs composite fiber diameter increased with the increase amount of MWNTs.XRD confirmed that when the MWNTs was0.2%, the crystallinity of the composite fiberswas the maximum value of17.28%, at the same time, the reinforcement effect was thegreatest, and the specific stress of fiber bundles increased from3.69cN/den to6.95cN/den.