Test Method for surface resistivity of Static-Free Clean Fabrics
B.1 Principle
Place an annular electrode on the sample surface of the insulated baseplate and load direct current on the electrode. Measure the surface resistivity of the sample based on the relationship between current, voltage and resistance.
B.2 Instrument
B.2.1 A group of electrode. Including a cylinder electrode and an annular electrode. Place the two electrodes concentrically. For other relevant parameters of the electrode, see SJ/T 10694.
B.2.2 A level baseplate for placing the sample. The surface resistivity shall be no less than 1.0×1012Ω/□, and the size shall be greater than that of the whole electrode.
B.2.3 A supporting resistance meter of the electrode group under B.2.1. Its range ability shall include but not limited to 1.0×105Ω～1.0×1011Ω.
B.3 Procedure
B.3.1 The test environment, sampling and pre-test processing shall comply with Appendix A. The size of the sample shall be greater than the external area of the annular electrode.
B.3.2 Where there is no sample, test the resistance of the level baseplate by the way of placing the sample and check if it meets the requirement of B.2.2.
B.3.3 Put the test side of the tested sample upward on the level baseplate and place the electrode on the surface of the sample. Connect to the electrode, load with voltage and read the resistance meter after 15s±1s (or the figure is steady). The on-load voltage should comply with Table B.1.
Table B.1 Selection of Testing Voltage
|
surface resistivity/(Ω/□) |
Testing Voltage/V |
|
1.0×104≤ρ＜1.0×106 |
10 |
|
1.0×106≤ρ＜1.0×1012 |
100 |
GB/T 24249-2009
B.3.4 Calculate the surface resistivity of the sample as per formula (B.1).
ρ=k×R ..............................(B.1)
Of which,
ρ—The surface resistivity of the sample, in Ohm per square unit (Ω/□);
R—The resistance measured by the resistance meter, in Ohm (Ω);
K—Geometrical factor of the electrode.
In particular, geometrical factor of the electrode will be calculated as per formula (B.2).
K=2∏/1n（r2/r1） ..............................(B.2)
Of which,
r1-Radius of the cylinder electrode, in millimeter (mm);
r2-Radius of the annular electrode, in millimeter (mm).
B.3.5 Select four test points to test (select four test points at both the front and reverse sides if necessary). Calculate the mean value as the decision value of the surface resistivity of the sample.