As with thermal management applications, electrical conductivity is traditionally thought of as the realm of high conductivity metals. However, polymers can also be designed and manufactured with varying levels of electrical conductivity by incorporating conductive additives. This allows designers to potentially be able to utilise the many advantages of polymers, whilst having the added benefit of being able to tailor the electrical conductivity of the end material to suit the application by varying the type and amount of additive utilised.
There are many additives which can be incorporated, with the common ones falling into several groups. There are permanent and non-permanent options and wide ranging abilities to increase conductivity. The final selection will depend upon the specific application requirements and ultimately the level of conductivity required.
When compounding polymers for electrical applications, the dispersion of the additive selected is of critical importance to the overall performance. This is particularly key with additives such as CNT’s and graphene, where the low addition rates possible mean that fully optimised dispersion is necessary in order to achieve percolation and hence a conductive network.
Typical measurements taken and utilised would be surface resistivity, volume resistivity and, for EMI shielding applications, specialised techniques for measuring the percentage of incident electromagnetic radiation which is reflected and/or absorbed by the shield material.