Key to Understanding Polymer Electrical Conductivity

Electrical Conductivity

Electrical conductivity is the degree to which a material conducts electricity. Electrical resistivity is the degree to which a material opposes the flow of electricity. A material with high electrical conductivity and low electrical resistivity indicates a material that readily allows the movement of electrical charge. A material with high electrical resistivity and low electrical conductivity indicates a material that opposes the movement of electrical charge. In general, polymer materials by themselves have high electrical resistivity and are, thus, electrical insulators.

There are three ranges of polymer conductivity/resistivity. They are:

  • Conductive
  • Static dissipative
  • Insulative

electrostatic

Applications for polymers used in environments where electricity is present needs to be managed and requires electrical conductivity, static dissipation, and electrical resistivity. Polymers in general, and styrenic block copolymer (SBC) thermoplastic elastomers, in particular, can be formulated to perform in all three of the above electrical ranges.

Conductive Polymers

A conductive polymer actually allows the flow of electricity on it and through it. The most popular way to functionalize materials to meet certain electrical application requirements is to compound in conductive carbon black to the formulation. Carbon black is an electrically conductive additive and depending on the particle size used and the amount added to the polymer, conductive, as wells as static dissipative ranges can be attained.

Static Dissipative Polymers

A Static dissipative polymer inhibits the build-up of electrical current across a material substrate due to “tribocharging”. Tribocharging is a term that denotes the process in which materials contact and rub against each other and then separate resulting in a static charge distribution on the polymer substrate. The result of the remaining static charge may be just a shock we experience after touching the substrate. This is called an “electrostatic discharge” or ESD. ESD can be far more damaging than a simple shock. ESD events can cause catastrophic events due to spark resulting from high static build-up on the polymer substrate. If an ESD event happens around explosives, the result could be devastating.

Static dissipative ranges can also be attained through the addition of inherently dissipative polymers or “IDP’s”. These polymers are inherently static dissipative and can be alloyed with resistive polymers to achieve static dissipation.

Insulative Polymers

An electrical insulative material keeps internal electric charges from flowing freely and, therefore, make it very hard to conduct an electric current in an electric field. SBC TPEs can serve as practical and safe insulators for low to moderate voltages, and, therefore, are an excellent material for insulating electrical wire and cables.

Electrical resistivity/conductivity are increasingly being sought after in the polymer world. Here at Star Thermoplastics we are able to formulate SBC TPE’s that meet your application requirements for electrical conductivity/resistivity.

Functionalized polymers provide an essential role in today’s industries.  They allow different industries to create new, better quality, scientifically advanced products easily and efficiently. By selecting the right material, the possibilities are endless. If you have any questions about the best styrenic TPEs for your application, let us know.

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3 Comments

  1. Colby Young Nov 25, 2015 at 5:12 pm - Reply

    Great Article! I mean not as impressive as leading a bus full of people in a rendition of the “The Fresh Prince of Bel Air” impressive. But very informative nonetheless.

    I actually have a question about electrical conductivity and SBS material. We are currently working on a grip design which incorporates an etched foil heating element that is molded in between two layers of grip material. Would it be possible to replace this heating element with a molded SBS that mimics the resistance of the foil etched element. I am not sure what the level of resistance is, but the current output to the element is 11.1V/3.5 amps.

    Also does the level of conductivity affect the ability to overmold the material to PP or other SBS compounds?

    Just trying to see if this is something we should look into. It could save a significant amount of cost and time in making these products if this was a viable replacement.

    Thanks and have a Happy Turkey Day!

    Colby
    ODI

    • Samantha Leenheer Nov 30, 2015 at 10:36 am - Reply

      Thanks Colby! Hope you had a great Thanksgiving as well. I am looking into your questions and hope to have an answer for you soon.
      -Samantha

    • Samantha Leenheer Jan 22, 2016 at 12:04 pm - Reply

      Thanks again for your question, Colby. It is a great question, and one not so easily answered in a quick response. We hope that our conversation with Joe provided you with what you needed. Always happy to help out.

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