## 2 Electrostatic Properties--The Charge Decay Method  
The EN 1149 standard [43] specifies test methods for textiles used in producing protective clothing with electrostatic dissipation to prevent incendiary discharge. The standard is divided into test methods for measuring surface resistance (EN 1149-1:2006) [44], vertical resistance (EN 1149-2:1997) [45], and charge decay (EN 1149-3:2004) [43]. The surface resistance is determined along the surface of the material, while the vertical resistance is the electrical resistance perpendicular to the surface. Textile can be conductive (\(R_{s}\leq 10^{4}\)\(\Omega\)), static dissipative (\(10^{4}<R_{s}\leq 10^{10}\)\(\Omega\)), or antistatic (\(10^{10}<R_{s}\leq 10^{11}\)\(\Omega\)) [1]. It has been found that the risk of ESD damage is minimized when the surface resistance of the conductive elements of the garment is within the range of (\(1\times 10^{5}\) to \(1\times 10^{11}\)\(\Omega\)) and there are no continuous insulating areas in the garment exceeding a size of about 20 mm \(\times\) 20 mm [46]. Resistive measurements are often used for qualifying materials where static electricity can cause problems or pose risks. Resistive methods are simple and reliable, especially when the surface resistance of the material under test is less than \(1\times 10^{11}\)\(\Omega\). In the case of fabrics with a core of conductive fibers, it is impossible to characterize the protective properties of ESD by any resistivity method because the measuring electrode cannot be in galvanic contact with the conductive elements of the textile. This paper uses the charge decay method to develop a model of two ESD protective textiles, a fabric, and a nonwoven fabric. Charge decay tests are the basis for evaluating antistatic textiles. The EN 1149-3 standard describes two methods of measuring charge decay in detail. The methods differ in the technique of generating electrostatic charge. The first method uses triboelectric charging, while the second uses induction charging. The second method, used during this research, is briefly discussed. It is possible to use a conductor's polarizability to acquire a charge without actually touching a charged object. This process is called charging by induction [47]. The electrification process is not sensitive to surface impurities. The electrostatic induction method utilizes the effect of polarizing a material under exposure to an external electric field. The grounding of the material during the interaction of the field causes a charge to move from the previously electrically neutral material to the ground. The value of the charge depends on the geometry of the system and the value of the electric field intensity (the electric field, in short). The time required to achieve a fully charged state depends on the electrical conductivity (\(\sigma\)) of the material. In the case of metals (high conductivity), the time is on the order of 0.1 ns. For materials with low conductivity, the time is measured in milliseconds. In antistatic materials, charge decay times are usually less than 1 s. The charge decay plot depends, among other things, on the concentration of charge carriers; the mobility of the carriers and the value of the charge (electrical conductivity); the mechanism of charge injection; and the properties of the electrode areas, temperature, and humidity. Inductive charging involves placing an electrode horizontally under the test specimen (Figure 3). The charge induced on the measuring electrode (2) is the result of the electric field existing in the area of the field-generating electrode (6)--specimen (8)--measuring electrode (2). The field is the result of two components. The first component depends on the field between the measuring electrode (2) and the electrode (6). The second component originates from the charge flowing in from the ground due to the finite conductivity of the material (8) and accumulating on the specimen surface. The charge builds up gradually over time and compensates for the field from the electrode (6).