Integration of carbon allotropes into polydimethylsiloxane to control the electrical conductivity for novel fields of application

Two-component polydimethylsiloxanes (PDMS) are particularly used as adhesives and sealants in the electronics industry. The fundamental properties of PDMS, like their electrical isolation, resistance against temperature, atmospheric conditions and many solvents, stoke the interest in many other applications. Furthermore, highly specialised applications of PDMS require additional properties like electrical conductivity, increased permittivity or adjustment of mechanical properties. Therefore, in such circumstances it is necessary to modify the PDMS to achieve the required additional properties. This modification can be achieved by integrating carbon allotropes, e.g. carbon black, graphite, graphene and carbon nanotubes. The processing of PDMS with nanoscale fillers can be done with different devices, which are based on different mechanisms of action. The main aim is to achieve a good and homogeneous dispersion with minimal effect on particle size. The different types of particles showed a variety of behaviours regarding their deagglomeration and homogenisation in the PDMS. This depends on the resilience of the agglomerates and therefore the energy required for deagglomeration. These different particles also produced different values of the electrical conductivity regarding their geometry. An additional factor was the further processability of the dispersion because some particles cause a drastic increase in the complex viscosity, which may be a limiting factor for the application. The investigations showed a wide range of influences on the dispersions and cured samples and also the related values, e.g. electrical conductivity, viscosity and processability. Research in the field of electrical modification of PDMS reached a high standard of knowledge. Now, the practical demands of the industrial operators and all those who are interested in to transfer the knowledge into new and promising applications will be necessary for the further action research. The parameters of the material may be adjusted to the demands, whereby the necessary properties for further applications will be realisable.