Influence of plasticizers (DOP and CNSL) on mechanical and electrical properties of SBS/polyaniline blends

Electrically conductive blends based on polyaniline-dodecylbenzene sulfonic acid (Pani.DBSA)/styrene-butadiene-styrene (SBS) block copolymer have been prepared in the presence of different plasticizers such as dioctyl phthalate (DOP) and cashew nut shell liquid (CNSL). The products were characterized by ultraviolet-visible (UV-vis) spectrometry, scanning electron microscopy, X-ray diffraction, electron paramagnetic resonance (EPR) and resistivity measurements. The presence of DOP resulted in an increase of the electrical resistivity whereas the increasing concentration of CNSL resulted in a decrease of electrical resistivity. In the latter case, the presence of cardanol, a phenol-type compound in CNSL, may be responsible for the improved electrical performance, probably because of a secondary doping process, which changes the molecular conformation of Pani.DBSA chains from “compact coil” to “expanded coil”. In addition, CNSL contributes to the formation of cocontinuous-type morphology with conducting pathways in larger extension. EPR studies also showed an increase of the polaron mobility as the amount of CNSL in the blend increases.