Xiao Changfa

Study on gel‐spinning process of ultra‐high molecular weight polyethylene

An ultra-high molecular weight polyethylene (UHMW-PE) fiber was prepared by gel spinning using general kerosene as the solvent and gasoline as the extraction solvent. The process of the phase separation of gel as-spun, spun under various spinning conditions, was investigated. Its extracting and drying process were also studied. The results reveal that the gel as-spun, spun under a lower spin draft and a lower spin quenching temperature, extracted in times and dried under free-shrinkage, exhibits a good afterdrawability that eventually endows the fiber with excellent mechanical behaviors.

Effects of Stretching Ratio and Temperature on Phase Transition of Melt-spun Poly （Vinylidene Fluoride） Fibers

The effects of stretching ratio and stetching temperature on phase transition of melt-spun poly (vinylidene fluoride) fibers were investigated and analyzed by using scanning electron microscopy, wide angle X-ray diffraction, differential scanning calorimetry and Fourier transfer infrared spectroscopy. The β phase exists in the as-spun fiber. The β phase content increases as the stretching ratio increases. When the stretching temperature is lower than 100°C, enhancing temperature is good for the transition of phase α to β. By contrast, when the stretching temperature is higher than 100°C, enhancing temperature is unfavourable for the transition of phase α to β. Increasing the draw temperature increases the α-phase content

Fabrication and properties of FEP fibers by melt spinning method

ABSTRACT Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) is a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) which not only maintains the excellent properties of polytetrafluoroethylene (PTFE) but also breaks the drawback of PTFEs hard melt-processability. In this study, FEP fibers were spun by melt spinning method using a single screw extruder. The obtained FEP fibers’ thermal and crystallization properties were investigated via DSC, XRD and DMA respectively. Results showed that FEP fibers’ melting temperature and crystallinity degree improved as the heat setting temperatures rising from 120℃ to 160℃. The melting enthalpy increased from 29.3 J/g to 31.5 J/g while the crystal temperature decreased from 233.8℃ to 232.1℃. The morphologies of FEP fiber showed that the grooves became light, and accompanied with the decrease of the fiber diameter when the nascent fiber suffered drawing.