In recent years

some scholars have found that there exists the relaxation time for the electrospinning jets during electrospinning

and the forming reasons have been partially explained. The impact on the resultant nanofiber morphology from the relaxation time of the electrospinning jets has not been investigated. As a matter of fact

the relaxation time of the electrospinning jets is linked to the charged nature of the spinning solution; meanwhile the electrospun fiber morphology could be closely related to the charged nature of the spinning solution

indicating that there are important connections between the relaxation time of electrospinning jets and the charged nature of the spinning solution. In this study

20% w/w PVA solution was used to conduct electrospinning experiments on the needle electrospinning equipment based on three different electric field setups

and the spinning jets were recorded with a high-speed video camera. Furthermore

the electrospinning mechanisms of these setups and the relationships between the electrospun nanofiber morphology and the relaxation time of the electrospinning jets were analyzed systematically

in combination with the electrospun fiber morphological features. The results indicated that the reason for the intermittency of the electrospinning jets was due to the existence of the relaxation time of the electrospinning jets

which could be directly linked to the accumulation speed of the ionic charges on the surface of the Taylor cone

and the latter could be attributed to many factors

such as the ambient atmosphere of the position of the spinning solution

the viscosity of the solution

the ionic concentration of the solution

the electric field intensity and voltage of the position where the solution is located at

and so on. As a result

the ununiformity of the electrospun fibers and the change in the surface morphology of the nanofiber materials could be attributed to the presence of the relaxation time of the electrospinning time.