Dielectric Testing of a Soft Elastomer

Why not test the dielectric strength as a solid and a liquid using the tests found already? Viscoelastic materials have properties of solids and liquids.

From what the testing labs I have talked to tell me, the ASTM standard for dielectric testing of solids specifies a certain amount of pressure between certain size electrodes and our material is so soft it just squeezes out.

I am not sure what the difficulty with the test spec for liquids is exactly, but one lab we have sent samples to was unable to complete the test and another lab looked at a sample of our material and said they could not use the test for liquids. The lab technician explained the reasoning to me, but it was a little bit over my head.

It just seems that we cannot be the only ones to try and determine dielectric strength of a viscoelastic material. There must be a standard or a procedure out there somewhere.

This is something which you can do in your lab, if you have a high voltage supply and the capability to send short pulses of high voltage to electrodes, as you may be able to construct with a common automotive ignition system.

The test virtually determines the maximum voltage that an insulating material can withstand for a given thickness. Start with a distance between electrodes where no electric spark is heard or seen when pulsed, and move them closer together until an electric spark is heard or seen. When that point is reached, you will know what the dielectric strength of your material is, given that you know what the voltage is between electrodes and the distance apart they are. It's that simple. You may want to derate it because of inconsistancy of material, in which case I would test several batches, but that's about all there is to it.

Thanks for the info. As my background is in chemistry I don't have the equipment or expertise to perform the tests "in house" but at least now I have a good idea of how to proceed and when a customer asks what the dielectric strength of our material is I will know how to answer.