Experimental Research On Electrospinning Of Normal Electric Field And Pulsed Electric Field

Phenolic fiber is a high-performance material with excellent fire resistant, corrosion-resistant and adsorption filtration. Currently, the preparation method by solution electrospinning is very complex and time-consuming, and the fiber applications also limited in adsorption and filtration fields. In this study, the orthogonal experiment design was applied to arrange the melt electrospinning experiment to prepare the pure phenolic fiber under the normal electric field. The results show that the temperature has the most important effect on the resultant average fiber diameter, followed by voltage, and finally the distance. The optimal preparation condition is 160 ?,8 cm,40 kV. The average fiber diameter was 4.44±0.76?m in this case. The thermal property of phenolic fiber was improved after crosslinked.Melt electrospinning can avoid the problems caused by the solvent and can also take full advantage of spinning materials, which is an eco-friendly and efficient method since no requires of solvent. However, due to the inherent high viscosity and low conductivity of the polymer melt, the obtained fiber diameter usually difficult to be reduced to nanoscale, which limiting the development of melt electrospinning. Existing improved methods can achieve a certain effect, but they will make it more different to control the spinning conditions or need more complex preparation equipments. Aiming at this problem, we introduced pulsed electric field to prepare PLLA (poly-L-lactic acid) melt electrospinning fibers, this method no needs additives, no extra equipments, and it will not increase the spinning step and difficult conditions.The study found that the pulsed electric field can reduce the PLLA fiber diameter under certain conditions. The crystallinity and molecular chain orientation of obtained fibers were better than that of normal electric field. The synergies of frequency and duty cycle may lead to complex changes of molecular chain orientation and crystallinity of fibers. The obtained fibers appeared multiple-necking structures at 8 and 10 KHz, which is rare in the micron fibers. After a detailed analysis, we believe that the effect of pulsed electric field on the melt electrospinning fibers was related to the degree of molecular chain entanglement.The polymer melt is sensitive to temperature and the viscosity is hard to precisely regulated, so we conduct the solution electrospinning experiment with PVP (polyvinylpyrrolidone) under pulsed electric field. First, we explore the impact of frequency and duty cycle with respect to the flow rate and voltage to the resulting fiber diameter. The results show that duty cycle has the greatest impact, while for frequency is not significant; fibers generated by pulsed electric field have thinner average diameter and wider diameter distribution. Is very important to figure out how the frequency and duty cycle and concentrations of PVP affect the fiber diameter, it is essential to understand the synergistic effect of frequency and duty cycle with the molten polymer molecular chain entanglement on the fiber diameter of melt electrospinning.