Investigation of electrical properties of thermoplastic elastomer based composites

Recently, a lot of research has been carried out about electrical conductivity of flexible polymeric materials. One of the most important research is to manufacture electrically conductive flexible composites by addition of conductive fillers into the electrically insulating polymers. In this study, styrene-ethylene-butylene-styrene (SEBS) which is a member of thermoplastic elastomer (TPE) family was used as a composite matrix. In SEBS while flexibilty is obtained by ethylene- butylene block; styrenes form physical crosslinks with secondary interactions and lead to formation of rigid regions. In order to obtain conductive composite structures carbon based fillers, such as graphite and reduced graphene oxide were added into SEBS polymer. Graphite was bought; reduced graphene oxide was prepared from graphite in the laboratory as a result of some reactions. For this aim, "modified Hummers Method" was used. In this method, large graphite particles were exposed to strong acid – oxidizing agent – and reducing agent, respectively and filtered then dried in a vacuum oven. Morphology of reduced graphene oxide was investigated by scanning electron microscopy and transmisson electron microscopy. Composites were basically fabricated by three steps. In the first step, polymer was dissolved in the solvent. In the second step, fillers were mixed with the solvent that followed by addition of the polymer solution and further mixing by a high shear mixer. Films are formed by solution casting of the mixture. After evaporation of the solvent, homogeneous films were obtained by a hot press. Electrical and morphological properties of composites were investigated and composites were compared in terms of polymer and filler type. According to results, electrical conductivity and morphology of a composite is affected by polymer and filler type.