Processing and characterization of conductive composites based on poly(styrene-b-ethylene-ran-butylene-b-styrene) (SEBS) and carbon additives: A comparative study of expanded graphite and carbon black

Electrically conductive polymer composites (ECPCs) based on poly(styrene-b-ethylene-ran-butylene-b-styrene) (SEBS) and expanded graphite (EG) or carbon black (CB) were prepared through melt blending using a torque rheometer equipped with a mixing chamber. Variations in parameters such as temperature, rotation speed and mixing time were investigated in order to define the most suitable processing conditions. The processing parameters investigated did not exert significant influence on the electrical conductivity for SEBS/EG composites, except for the mixture processed at 230 degrees C and 150 rpm for 15 min. On the other hand, it can be stated that the conductivity of the SEBS/CB depends on the processing temperature and mixing time. The electrical conductivity, morphology, dynamic mechanical, dielectric and rheological properties as well as electromagnetic interference shielding effectiveness (EMISE) of the SEBS/EG and SEBS/CB composites prepared under the same processing conditions were evaluated and compared. The insulator conductor transition of SEBS/CB was very sharp and the electrical percolation threshold at room temperature was about 5 wt.% of CB, which was significantly lower than that of 9 wt.% for SEBS/EG composites. It was also observed that EMI SE value depends on its electrical conductivity. The EMI SE acceptable value for SEBS/CB composite with 15 wt.% of CB indicates that this materials are promising candidates for shielding applications. (C) 2015 Elsevier Ltd. All rights reserved.