Double PTC effect of carbon nanotubes filled immiscible polymer blends

Carbon nanotubes (CNTs) and poly(styrene- co- maleic anhydride) modified CNTs (SMACNTs) were blended with an immiscible system polystyrene/nylon6 (PS/PA6) to prepare conductive polymer composites PS/PA6/CNTs and PS/PA6/SMA-CNTs respectively. The PTC (positive temperature coefficient) effect of the composites was investigated. For PS/PA6/CNTs composites, CNTs were selectively distributed in PA6 phase; the percolation threshold was 5% (mass fraction) and a weak PTC effect was observed. For PS/PA6/SMA-CNTs composites, TEM results showed that CNTs were distributed both at the PS/PA6 interface and in PA6 phase due to the induced effect of SMA on CNTs. As a consequence, the percolation threshold decreased to 0.112%. Meanwhile, an especial double PTC effect was observed. The PTC effect was affected by the morphology of PS/PA6 blends. The emerge of PTC effect of the composites with dispersed PA6 phase was attributed to the glass transition of PS phase and the melt of PA6 phase. However, for blends with PS as disperse phase and PS/PA6 as bicontinuous phases, the emerge of PTC effect was due to the melt of PA6 phase. © Copyright.