## 4 Results and Discussion
### Laboratory Tests  
Both textiles shown in Figures 1 and 2, i.e., the protective nonwoven fabric and ESD protective fabric, were tested in an accredited laboratory. The nonwoven fabric is made of polyester fibers (3.6 dex) placed in random directions and has internal cohesion ensured by a mechanical method. The grid of conductive fibers is embedded. Additionally, the felt was fired and impregnated with an oleo-hydrophobic substance. The fabric shown in Figure 2 is a plain-weave fabric made of 9 tex x2 polyester/cotton fibers and 12 tex polyester/carbon-coated fibers. The most important information and parameters of the tested textiles are included in Table 1.  
During laboratory tests, a measurement device was used to determine charge decay time (Figure 18a). The device was connected to a laptop with dedicated software installed to control the measurement process. The key parameters of the setup are as follows: time resolution of 50 us (sampling frequency 20 kHz), a charge amplifier (electronic electrometer) with a range of 1 pC to 2 nC, 16-bit measurement resolution, input impedance of 1 G\(\Omega\), and rise time of 0.2 V/us. The laptop used during the test was running on battery power, and the measurement setup was powered on for 10 min before the test began. The setup was located in a Binder Climate Chamber KBF 240, Binder, Tuttlingen, Germany. The tests were conducted in accordance with the steps outlined in the EN 1149-3 standard using three textile specimens. The test procedure involves the following steps:  
1. Cutting three specimens (each at least 300 mm square, excluding seams);
2. Determining the initial maximum field strength without a specimen (\(E_{max}\));
3. Conducting the following measurements with the specimen: *  
Charge decay plots were recorded, and the time (\(t_{50}\)) and electrostatic shielding value (\(S\)) were determined for three specimens of each textile under two climatic conditions (at 23 \({}^{\circ}\)C and 25% relative humidity (RH); 28 \({}^{\circ}\)C and 52% RH). In the case of a nonwoven fabric made of polyester fibers and a conductive grid using stainless-steel fibers, the nonwoven textile was additionally fired and treated with oleo-hydrophobic impregnation. The additional pretreatment positively impacts the antistatic properties, significantly increasing the effective electrical conductivity by about three orders of magnitude compared to untreated nonwoven polyester fabric. The time (\(t_{50}\)) is less than 0.01 s for all specimens under all climatic conditions. For the nonwoven fabric under the climatic conditions established in the 1149-3 standard, the average value of \(S\) equals 0.61, and at 28 \({}^{\circ}\)C and 52% RH, the average value equals 0.66. As expected, at higher humidity, the conductivity of the specimen increases, and oleophobic impregnation enhances the effect. Figure 19 shows the charge decay plot for nonwoven fabric under standard climatic conditions. For ESD protective fabric under standard climatic conditions, an average value of \(S=0.97\) is obtained. At 28 \({}^{\circ}\)C and 52% RH, the average value of \(S\) equals 0.98. Figure 20 shows the charge decay plot for the fabric under standard climatic conditions.  
Figure 19: Charge decay plots for nonwoven polyester antistatic fabric at 23 \({}^{\circ}\)C and 25% RH measured in a laboratory.  
Figure 18: Photo of the laboratory bench. (**a**) Nonwoven fabric specimen placed in the terminals of the charge decay instrument; (**b**) residual charge neutralizer moved over the specimen; (**c**) the obtained results.