Determination of volume resistivity of HYT-036 liquid plasticizer GB1672-88
Standard description
1. Subject content and scope of application
This standard specifies the method for determining the volume resistivity of liquid plasticizers.
This standard applies to the determination of the volume resistivity of liquid plasticizers. Other liquid auxiliaries can also be referred to the present assay.
2. Definition of volume resistivity
It is the ratio of the DC electric field strength in the direction of the sample volume current to the current density at that point, expressed in Ω?m.
3. Sample
3.1 The liquid plasticizer sample is used for about 40ml each time.
3.2 The sample shall be free of air bubbles and impurity defects.
3.3 The sample should be placed at a temperature of 23 ± 2 ° C and a relative humidity of 60-70% for more than 2 h.
4. Test instruments and electrodes
4.1 High resistance meter
The following requirements should be met when testing high resistance meters:
a. The high resistance meter measurement range should include 1*106-1*1017Ω.
b. When the resistance is greater than 1012Ω, the measurement error is less than ±20%; when the resistance is equal to or less than 1012Ω, the measurement error should be less than ±10%.
c. Zero drift is no more than 4% of the full scale per hour.
d. The insulation resistance of the input wiring should be greater than 100 times the input resistance of the instrument.
e. The test circuit should have good shielding.
f. The instrument should be verified periodically.
4.2 Electrode
The electrodes should be made of brass or stainless steel. The inner diameter of the high voltage electrode is 146 mm, the outer diameter of the measuring electrode is 120 mm, the width of the guard ring is 8 mm, the gap between the measuring electrode and the high voltage electrode is 2 mm, and the roughness of the working surface of the electrode is 1.6 or less. The switch and dimensions of the electric stage are shown in Figure 1.
5. Determination steps
5.1 Pour the treated sample into the high voltage electrode so that the liquid surface is just in contact with the measurement surface.
5.2 The test shall be carried out in an environment with a temperature of 23 ± 2 ° C and a relative humidity of 60 - 70%.
5.3 During the test, the voltage applied to the sample is a DC voltage of 100-500V.
5.4 Connect the electrode to the measuring end of the instrument, adjust the instrument, and operate according to the instrument manual. Add the test voltage for 1 min, read the indication value of the resistance, and simultaneously measure the sample twice, taking the arithmetic mean of the two results. The sample and the ground electrode were discharged for 1 min after each measurement.
6. Calculation
The volume resistivity Ïv(Ω?m) is calculated according to formula (1)(2):
S=Ï€/4(D+g)2 (1)
Ρv=Rv(S/d) (2)
Where Rv - volume resistance, Ω;
S——the effective area of ​​the flat measuring electrode, m2;
D——plate measuring electrode diameter, m;
G——measuring electrode and guard electrode gap width, m;
D——sample thickness, m.
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