Preparation And Research Of Electrospun Polyurethane (PU)/Single-wall Nanotube (SWCNTs)Composite Fibers Mats

Nanofibers have lots of special properties, such as large surface areas, light quality and fine diameter etc. which are widely used in filtration and biomedicine and so on. In this process, electrospinning is an important method in fabricating of nanofibrous structures. However, the strength of electrospun nanofiber mat is low, which restricts its applications in many fields. In this article, focusing on strengthening nanofiber mats and investigating their properties from all aspects by adding signal-wall carbon nanotube(SWCNTs) in polymers solutions and preparing electrospun nanofibers with high orientation.Polyurethane (PU) is used to do the trial experiments of producing nanofibers by electrospinning. Firstly, the properties, including polymer solution, diameters and morphologies of the fibers, are investigated by using the method of orthogonal design. Then getting the optimal processing parameters of PU in electrospinning:the concentration is15wt%, the voltage is15kV and the receive distance is20cm.Then, the PU/SWCNTs solutions and nanofibers are prepared with different concentrations of SWCNTs (0%-3.0%). The results show that the viscosity, conductivity and surface tension of polymer solution all increase with adding more SWCNTs to polymer solutions. The diameters of nanofibers become smaller while numerous beads appear which influence the uniform of the fibers. The result of TEM shows that the SWCNTs have better arrangement along the fiber axial. On that basis, the PU/SWCNTs mats are manufactured by the methods of adding SWCNTs and being orientated.Comparing the microstructures of nanofibers collected by both methods above, the Infrared Spectrum result shows that neither SWCNTs nor orientation affect the molecule group of PU, which indicates that the effect is not obvious to the structure using different collecting methods. The crystalline of PU/SWCNTs fibers is investigated by X-ray Diffraction and DSC, the testing result demonstrates that the concentration of SWCNTs doesn’t affect the crystallinity of PU while the orientation results in the decrease the degree of crystallinity.The properties of PU/SWCNTs mats are further investigated between no-orientation and orientation forms. The strengths of mats change with different concentrations of the SWCNTs. And the maximum breaking tensile strength is12.18Mpa when the concentration of the SWCNTs is0.5wt%, which is about2times more than pure PU(6.65MPa) electrospun nanofiber mats, and the nanofiber mats with orientation get more strength as much as25.65MPa, which is2.1times higher than those non-orientated ones. However, the strength become lower with the increasing of the SWCNTs’ concentration; besides, the electrical conductivity and contact angle of PU/SWCNTs nanofiber mats are generally improved compared with that of pure PU mats. The diameters of pore decrease originally and then increase at the critical concentration of SWCNTs. To some degree, these properties of orientated mats, including electrical conductivity, diameters of pore and contact angle of nanofiber mats, all have some changes in comparison with non-orientated ones.