Welcome to Imerys Performance Minerals

Electrical properties

Electrical properties

Imerys calcined kaolins deliver excellent electrical insulating properties in low, medium and high voltage cables. Our conductive carbon blacks are a good choice for boosting electrical conductivity in rubber compounds.

Electrical insulation

Rubber cable insulation is primarily based upon Ethylene-Vinyl Acetate (EVA) or Ethylene-Propylene Rubber (EPR or EPDM).

The major filler used within low/medium EPR and EPDM cable insulation to achieve low dielectric loss and excellent electrical performance is calcined kaolin.

Calcined kaolins, such as our Polestar 200R grade,  impart excellent electrical insulation properties to low and medium voltage power cables. Their low moisture absorption properties ensure that insulation properties are maintained under wet operating conditions.

For medium to high-voltage compounds, silane-treated calcined kaolins are more suitable. Our Polarite™ 503S is a vinyl functional silane-treated calcined clay developed for use in very high voltage cable insulation based on EPR. Polarite 503S imparts extremely good dielectric properties at high working temperatures and under wet conditions for the working life of the cable. It also gives good insulating properties in other polymers such as EPDM, crosslinked polyethylene and ethylene vinyl acetate copolymers.

Calcined kaolins not only impart excellent insulation properties but also provide very smooth surface finish and excellent dimensional control, due to the low die swell imparted by the mineral.

Electrical conductivity

Conductive carbon blacks are the solution of choice where electrical conductivity is a performance criteria.

Our Ensaco® carbon blacks are a special family of highly pure carbon blacks, produced through a proprietary method that delivers products with a high structure/low surface area or very high structure/very high surface area, depending on the grade. 

Ensaco® carbon blacks are suitable for boosting electrical conductivity in EPDM and NBR among others.

For document downloads and enquiries about our Graphite and Carbon solutions, please visit the Imerys Graphite & Carbon website.

We offer a full range of bespoke formulation and technical and process support services to help you match the right mineral grade to your application requirement.

Please contact us, we will be only too happy to help

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Rubber