Preparation And Properties Of Fluoropolymer Fibers

Fluoropolymer has chemical corrosion resistance,high temperature resistance,aging resistance,abrasion resistance,excellent surface properties,flame retardancy and photoelectric properties.Due to the properties of fluoropolymer,fluorinated fibers are attractive as high performance fibers.Fiber and its products have potential in the fields of electronic and electrical,textile,aerospace,architecture,medicine,transportation,filtration and other fields.The fundamental purpose of this paper is researed the properties and prepared process of three kinds of thermoplastic fluoropolymer fibers:poly(vinylidene fluoride-co-hexafluoropropylene)[P(VDF-HFP)]fibers,polyvinylidene fluoride(PVDF)fiber,and perfluoroethylene propylene(FEP)fiber,respectively.First,P(VDF-HFP)nascent fibers were trial-manufactured by melt spinning method using plunger type spinning machine.Later,nascent fibers were drew by electronic tensile testing machine in high temperature(90 ?)and studied different draw ratios how to influence structures and properties of fibers.In addition,the effect of HFP monomer on the fiber structure is also studied.Next,the single-screw melt spinning machine was used to prepared continued and uniform P(VDF-HFP)filaments.Finally,P(VDF-HFP)yarns were prepared by the homemade P(VDF-HFP)filaments via twisting technologies.Then semi-automatic loom was used to weave plain fabrics and evaluated the properties of fabrics.The results showed that:The crystal structure,melting behavior and mechanical properties of the fibers were investigated by X-ray diffraction technology,fourier transform infrared spectrum(FTIR),differential scanning calorimeter(DSC),thermogravimetric analyzer(TG)and fiber strength tester.The results revealed that the crystallization morphology of P(VDF-HFP)fiber had ? and ? polymorphic forms,which was similar to PVDF fibers,contributed to the regularly stacking of vinyl idene fluoride(VDF)moieties.The addition of HFP had an effect on crystallization,resulting in lower crystallinity of P(VDF-HFP)fibers.The increase of drawing ratio not only facilitated the transition of crystalline phases from ? to ? phase,but also improved the crystallinity of the fiber.When the tensile strength was equal,the transformation of the crystalline form from a to P phase was more in the P(VDF-HFP)fiber than that in PVDF fiber,which is due to the steric effect in HFP structural unit.The fibers' thermal stability improved and their crystallization consummated with stretching.The melting temperature and thermal decomposition temperature of P(VDF-HFP)fibers under the drawing ratio of 6 times could reach 126.9 ? and 452.3 ?,respectively.With the increase of the draw ratio,the tensile strength increased owing to the regular rearrangement of molecular chains along with the axial direction,and the optimum tensile strength of P(VDF-HFP)fibers was as high as 502.6 MPa at the drawing raio of 6 times.After repeatly stretched for 50 times under the constant elongation of 20%,the elastic recovery rate of P(VDF-HFP)fibers under the drawn ration of 6 times was 81%which was much higher than that of PVDF fiber,indicating that the introduce of the HFP segments into the PVDF molecular chains was beneficial to improve the flexibility of the fibers.Three kinds of fluoropolymer fibers were manufactured by single screw melt spinning machine in different drawing ratio and different drawing temperatures.The crystalline structure,thermal properties,mechanical properties and dimensional stability properties of the fibers were studied.It turned out that the crystallinity of PVDF fiber and HFP fiber is higher than 50%,and the crystallinity of P(VDF-HFP)fibers is lower(the highest is 40%).The tensile fracture strength of PVDF fiber is the highest,which is 2.42 cN/dtex,and the tensile fracture strength of P(VDF-HFP)fiber and FEP fiber are all lless than 1.0 cN/dtex.The dimension stability of FEP fiber is the highest,and the dry heat shrinkage rate of fiber is only 1.8%at 120 ?.The fabric was tested by P(VDF-HFP)fiber and its performance was tested.The results showed that the moisture permeability of the fabric is 15646.64 g/(m2·24h),and the permeability of the fabric is 639.17 mm/s,which showed superior air and moisture permeability,and was expected to be used as waterproof and moisture permeable fabric.