Multi-needle, electrospun, nanofiber filaments: effects of the needle arrangement on the nanofiber alignment degree and electrostatic field distribution

Nanofiber filaments were produced by a home-made, multi-needle, liquid bath, electrospinning device, and the nanofiber alignment degrees of the filaments were investigated. The electrostatic fields of the multi-needle, liquid bath, electrospinning processes were simulated by the finite-element method, and an index, the average offset of the electrostatic field distribution in the needle tips, was established to quantify the existing electrostatic field interference. The effects of the number and the arrangement of the needles on the alignment degrees of the nanofibers and the breaking stress of the filaments were analyzed. The results showed that there was a linear negative correlation between the nanofiber alignment degrees and the number of needles with an R ² of 0.96. The larger average offset indicated the stronger electrostatic field interference, and a logarithmic positive correlation was determined between the average offsets and the number of needles with an R ² of 0.99. There was a linear negative correlation between the nanofiber alignment degrees and the average offsets with an R ² of 0.97. Meanwhile, when the average offsets in different numbers of needles increased from 0 to 0.160 mm, the average alignment degrees decreased from 0.964 to 0.774. Therefore, the optimal needle arrangement with the lowest average offset for each number of needles could be obtained. In addition, the breaking stress of the filaments decreased with the increase of the average offsets in the same number of needles, and the average breaking stress decreased initially with increasing the number of needles until three needles and then increased.