Volume resistivity tests

Material, pot life, bond strength, and 3.8.4 volume resistivity testing performed... 

The electrical conductivity data of grease was obtained by volume resistivity test cells made by Electro-Tech Systems, Inc. (ETS) [27]. The cell dimensions automatically calculate the volume resistivity of the material being tested by multiplying the measured resistance by either 10 (large cell) or 100 (small cell). The stainless-steel container acts as both an electrostatic shield and provides containment of material overflow. The test cell is made from PVC and uses stainless-steel electrodes. Figure 19.4 shows a diagram of the test cell. 

Figure 19.4 Volume resistivity test cells (a) assembled (b) in parts. (Reproduced with kind permission from NLGI. Copyright (2010) NLGI)...

Shelf life >12 mo -40°C for one-part s5fstems >12 mo 32°C for two-part systems. Shelf life is not extendable for Class K devices may be extended once for Class H devices 3.4.4 Material, pot life, bond strength, and volume resistivity testing performed 3.8.4... 

The largest volume of hydrauHc fluids are mineral oils containing additives to meet specific requirements. These fluids comprise over 80% of the world demand (ca 3.6 x 10 L (944 x 10 gal))- In contrast world demand for fire-resistant fluids is only about 5% of the total industrial fluid market. Fire-resistant fluids are classified as high water-base fluids, water-in-oil emulsions, glycols, and phosphate esters. Polyolesters having shear-stable mist suppressant also meet some fire-resistant tests. 

Electromagnetic interference (EMI) testing has become more prevalent for materials that either emit or are affected by EMI. Shielding efficiency (SE) of materials is deterrnined by measuring electric field strength between a transmitter and receiver with or without the presence of the material under test. Several researchers have suggested a correlation between volume resistivity and SE values (300,301). 

IEC 60093, Methods of test for volume resistivity and surface resistivity of solid electrical insulating materials, 1980. 

Because the surface of rubbers may conduct electricity more easily than the bulk of the material, it is usual to distinguish between volume resistivity and surface resistivity. Volume resistivity is defined as the electrical resistance between opposite faces of a unit cube, whereas surface resistivity is defined as the resistance between opposite sides of a square on the surface. Resistivity is occasionally called specific resistance. Insulation resistance is the resistance measured between any two particular electrodes on or in the rubber and, hence, is a function of both surface and volume resistivities and of the test piece geometry. Conductance and conductivity are simply the reciprocals of resistance and resistivity respectively. 

The usual standard methods for volume and surface resistivity both use the same test piece and electrode geometry and essentially the same measuring circuit. There are no ISO or IEC methods for rubbers but, where national standards specifically for polymers exist, they are usually adaptations of the IEC Publication 600931 for insulating materials in general. The relevant British Standards for rubbers are BS 903-C12 for surface resistivity and BS 903-C23 for volume resistivity. ASTM has an equivalent to the IEC standard for insulating materials generally, D2574, but no standard specifically for rubbers. 

Volume and surface resistivity tests for conductive and antistatic materials include ... 

Standard test method for rubber property-volume resistivity of electrically conductive and antistatic products Specification for electrical properties of conducting and antistatic products made from flexible polymeric material... 

D 2739 Test Method for Volume Resistivity of Conductive Adhesives... 

Current commercial practice for evaluating volume resistivity of printed conductive material relies on the overall dimensions of the test specimen, such as in the ASTM F1896 standard "method for... 

Because of the effect of atmospheric and absorbed moisture on volume resistivity, it is usually suggested that this test be performed at ambient and low relative humidity conditions. 

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