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. (c) 2006 Elsevier Ltd. All rights reserved.