A common question people ask is: can rubber conduct electricity? The answer depends on the material that is being used. If the rubber material does not contain any conducting electrons, then it will not conduct electricity. Rubber is known to be an insulator because rubber can limit the transfer of electricity. The rubber properties prevent the electrons to be able to freely move and the addition of the electrons being tightly bounded makes rubber a good insulator . Rubber itself usually cannot conduct electricity without any assistance.
Rubber as a conductor
Rubber are poor conductors of electricity hence the reason you see electricians wear rubber gloves when they are working with electric wires. This does not guarantee that the person does not get electrocuted because if there is strong enough of voltage then that object may still conduct electricity such as power lines. Another method that rubber becomes a conductor is if the rubber material gets wet and may pose a risk to the person touching the wet rubber. In addition, if you have a rubber that has additives such as carbon or metallic additives mixed with it then it may have electrical properties. Example of a conductive additive that is extremely additive is single-wall carbon nanotubes. Single wall carbon nanotubes are known to be a nanofiller with properties such as 6 orders of magnitudes higher than copper and high current carrying capacity making SWCTN’s a remarkable source for electrical conductivity. Single wall carbon nanotubes can also provide the advantage of improving elastomer properties such as tensile strength, making the material able to withstand heavier mechanical loads according to research from Nanowerk(https://www.nanowerk.com/nanotechnology-news/newsid=39408.php).
What is Conductive Rubber?
Definition: Conductive Rubber is a generic term referring to any rubberized material with conductive properties which reduce or eliminate the EMI/RFI (electromagnetic interference and radio frequency interference) “noise” that is often associated with electronics.
While there are a handful of materials that might be considered Conductive Rubber, this article will be focusing on the three common material types. Multicon (oriented wire in either sponge or solid silicone) Conductive Silicone (metallized filled silicones), and Radthin (wire screen imbedded into silicone). Each material is unique in its construction as well as its performance. Please see product description below for more detail.
Multicon material is one of the most prevalently used forms of conductive rubber today. It’s a combination of silicone and conductive wire paths which provides a superior environmental seal while providing EMI/RFI shielding to frequencies up to 6 GHz.
Multicon is offered in either solid or sponge silicone with either monel or aluminum wires for conductivity. The conductive wires are dispersed throughout the width of the material to provide great protection against EMI/RFI contamination. It’s constructed in such a way that when pressure is applied to the gasket, hundreds of sharp wire ends become exposed making electrical contact with mounting surfaces.
Multicon can be provided in a wide range of thicknesses and widths to meet the needs of a specific application, or the material can be die-cut to meet various configurations.
Another widely popular form of Conductive Rubber is Conductive Elastomer. Like Multicon, Conductive Elastomer can be die-cut to form a flat gasket but one of the large differences from other materials is that Conductive Elastomer can also be provided in a variety of different extruded profiles. Common profile configurations of Conductive Elastomers are: “D”, Round, “P”, Square, and Rectangular; these profiles can be extruded as a solid cross section or hollow depending on the compression required and height of the open aperture to be shielded. See Figure #1
MIL-DTL-83528 and Commercial Conductive Metallized Filled Silicone Elastomers:
- Rectangular Profiles
- Standard “D” Shapes
- Standard Rounds
- Custom Configurations
|Military Grade / Standard Silicone|
|Military Grade / Fluorosilicone|
|Military Grade / EPDM|
|Military Grade / Fluoroelastomer Co-Polymer|
|Military Grade / Combination: Conductive / Non-conductive|
|Commercial Grade / Standard Silicone|
|Commercial Grade / Fluorosilicone|
In Conductive Elastomer the base rubber is usually comprised of compounds such as silicone, fluorosilicone, or EPDM (ethylene propylene diene monomer). The use of a specific rubber is based upon the properties unique to each and determined by the intended environment and application. For example, silicone is used for general weather sealing and high temperatures to 400 deg. F. Fluorosilicone is used for applications where exposure to jet fuel, gasoline, and alcohols are present. EPDM is used for applications where exposure to coolants, steam, phosphate ester, or where supertropical Bleach (STB) is used.
After choosing a specific rubber suited for the intended environment, a conductive filler must be determined. Some of the most common conductive metal fillers used are silver aluminum, silver glass, silver copper, and nickel graphite.
Determining the right filler is dependent on the level of shielding needed for a specific application, the more conductive the filler the higher the level of shielding achieved. Once the parameters have been determined, the table below can be used to establish which Conductive Elastomer is right for the application.