取向聚氨酯纳米纤维膜卷纱的制备及其力学性能

Preparation and mechanical properties of yarns made from rolling oriented polyurethane nanofiber membranes

为解决纳米纤维膜强力低、使用稳定性差的问题,通过将聚氨酯(PU)树脂溶于二甲基甲酰胺和四氢呋喃中制备纺丝液,再经静电纺丝制备纳米纤维膜,并通过加捻和热定形制得PU纳米纤维膜卷纱。比较了纳米纤维膜和膜卷纱的表面形貌,对纳米纤维膜卷纱的力学性能、热学性能和孔隙率进行了测试。结果表明:当纺丝液中PU质量分数为14%和15%时,纤维成膜性良好;纳米纤维膜卷纱表面纤维表现出明显的取向性,较粗的取向纤维与较细的非取向纤维相互连接形成网络结构;随着PU质量分数的增加,取向纤维比例明显增加;与纳米纤维膜相比,纳米纤维膜卷纱的断裂强力、拉伸性能明显提高;当PU质量分数为15%时,PU纳米纤维膜卷纱的断裂强度最高,为0.84 cN/dtex,弹性回复率为98%;PU质量分数为14%的纳米纤维膜卷纱经100次拉伸的弹性回复率为83%;热定形纳米纤维膜卷纱的比表面积为1.6362 m^(2)/g,孔容为2965 m^(3)/g,平均孔径为12.39 nm。

Objective Electrospun nanofiber membranes have shown the shortcomings of low strength and poor stability for certain applications.To compare the mechanical properties of membranes and yarns and to further discuss the feasibility of industrial production of membrane-rolling yarns,polyurethane(PU)nanofiber membranes were prepared by needle-free electrospinning and membrane-rolling yarns were made by twisting and heat setting.Method The PU nanofibrous membranes were prepared by the needle-less electrostatic spinning.Membrane-rolling yarns were prepared by bundling nanofiber membranes through a self-made twisting instrument,which was held at one end and twisted at the other.The membrane-rolling yarns were heat-set.The mechanical properties,surface properties and internal porosity of PU nanofibrous membranes and yarns were characterized by the scanning electron microscope,tensile tester and high-speed automatic specific surface and porosity analyzer.Results Spinning solution was formed by dissolving PU particles in the mixed solution of dimethylformamide and tetrahydrofuran(mass ratio 1∶1).The concentration of PU in spinning solution has great influence on the surface morphology of nanofibrous membranes.With the increase of PU mass fractions,the diameter of nanofibers became larger,and the membrane forming ability was enhanced.When the mass fraction of PU was between 13%and 15%,the morphology of nanofibrous membranes were found to be stable and the nanofibrous diameters were uniform.The surface of the membrane-rolling yarns was smooth,and because the fibers were arranged along the direction of force during twisting,the surface of membrane-rolling yarns representing a three-dimensional network structure composed of oriented fibers and non-oriented fibers.With the increase of PU mass fractions,the diameters of the oriented fibers became thicker and the proportion of oriented fibers was increased.From the performance point of view,PU membrane-rolling yarn showed higher mechanical properties compared with nanofibrous membrane,and its tensile strength were slightly lower than that of commercially PU filaments.When the mass fraction of PU is 15%,the elastic recovery rate of PU membrane-rolling yarn reached 98%,and when the mass fraction of PU was 14%,the elastic recovery rate of PU membrane-rolling yarn(stretching 100 cycles)reached 83%.Before and after heat setting,the temperature did not have a great influence on the structure and properties of PU nanofiber membrane yarn,so the strength of membrane yarn did not change significantly.It was found that the nanofibrous membrane and the membrane-rolling yarn were porous in both meso and micro scales.The surface area of membrane-rolling yarn was 1.6362 m^(2)/g,the pore volume is 2.965 m^(3)/g,and the average pore size is 12.39 nm.Conclusion This work confirms a new idea for the efficient production and use of nanofibrous yarns.The prepared PU membrane-rolling yarns have the characteristics of high strength and high elastic recovery.Moreover,the PU membrane-rolling yarn has the advantages of high porosity,specific surface area and activity due to the composition of the nanofibers.Therefore,for PU membrane-rolling yarns itself,it can be applied to sound-absorbing textiles,filter materials and so on,and the PU membrane-rolling yarns could potentially be loaded with functional particles and applied to various functional and smart textiles.