**1. Introduction**

#### **1.1. Electrospinning principle for manufacturing non-woven fabrics**

The electrospinning method, as a versatile nanofiber preparation process, has drawn great attention in the past decades, due to its simple setup, easy process, extensive material options, and capability to form non-woven fabrics without any post processes.

The origin of electrospinning as a viable fiber-spinning technique can be traced back hundreds of years [1]. The process of electrospinning, also termed electrostatic spinning, was first

conceived by Lord Rayleigh [2] in the late 19th century. In 1902, Morton [3] and Cooley [4] disclosed a patent using the electrospinning process via a composite solution. This patent was issued for the production of fibers from a solution jet using an electric field. From 1934 to 1944, Formhals published a series of patents [5-9], describing an experimental setup for the produc‐ tion of polymer filaments using an electrostatic force. Since then, electrospinning truly emerged as a feasible technique for spinning fibers with small diameters.

**Figure 1.** Diagram showing the principle of the electrospinning process.

A formal electrospinning process can be defined as below [10]: a polymer solution or melt is held at the end of a capillary tube and is subjected to a high static electric field (commonly 1-6\*106 V/m); the charges are then induced on the liquid surface; the mutual charge repulsion causes a force directly opposite to the surface tension; as the intensity of the electric field increases, the hemispherical surface of the solution or melt elongates to form a conical shape known as a Taylor cone; when the static electric field surpasses a critical value, the repulsive electrical forces overcome surface tension forces, resulting in a charged jet ejected from the tip of the Taylor cone. The route and thinning of this jet can be controlled by the electric field. At the same time, the solvent either evaporates or the polymer melt solidifies, leaving behind a charged polymer fiber. Continuous fibers are finally collected in the form of a non-woven fabric.

Electrospinning technology uses a totally different method for non-woven fabrics than the manufacturing in any other methods used in industry. The excellent characteristics of electro‐ spinning technology include the following.
